Handbook of Systematic Malacology, Part 3 (Scaphopoda / Bivalvia / Cephalopoda) [Annotated English-language edition of: Thiele, J., Handbuch der systematischen Weichtierkunde, Teil 3]

Rüdiger Bieler

This is the second part of a series on the German zoologist Johannes Thiele (1860-1935) and comprises a critical listing of the genus-group taxa which he described as new to malacology. Each of these names is accompanied by author and bibliographic references, original status, type-species with its original binominal spelling and bibliographic source and some data on subsequent taxonomic placements. Thiele introduced a total of 291 such names in the Phylum Mollusca, distributed as follows: 11 Aplacophora; 39 Polyplacophora; 200 Gastropoda (138 Prosobranchia; 20 Opisthobranchia and 42 Pulmonata); 31 Bivalvia; 10 Cephalopoda; there were no new scaphopod or monoplacophoran names. Of these, later authors recognized as valid 85 at the generic level, 110 at the subgeneric level; 71 are considered to be synonyms, and the remaining 25 are unjustified emendations or errors.

Waagen (1875) was the first who dealt with the Jurassic ammonites of Kutch based on detailed taxonomic work. In his monograph, he described among many species Perisphinctes spirorbis Neumayr, 1870 and P. aberrans Waagen, 1875 from the Callovian of Kutch, but the figures mentioned in the description did not correspond to the actual species. For P. spirorbis, the plate illustrated the holotype of an entirely different species (P. aberrans). On the other hand, P. spirorbis was illustrated as the lectotype of P. aberrans. Later, Spath (1924) introduced a new genus, Subgrossouvria, based on Waagen’s P. aberrans as type species. He also erected another genus, Indosphinctes, and included P. spirorbis Waagen, 1875 within the synonymy of I. indicus (Siemiradzki, 1899). Spath (1931) was aware of wrong numbering of plates of Waagen’s two species. But subsequent workers were ignorant of these taxonomic errors and continued to refer Waagen’s wrong plate numbers. We have here described both the t...

HANDBOOK OF YSTEMAFIC MALACOLOGY PARTS 3 AND4 JOHANNES THEELE Johannes Thiele (1860-1935) was one of the most productive systematists of his time. His probably best-known work, the Handbuch der systema- tischen Weichtierkunde (1929-1935), completed only months before his death, has become an indispensable source of information for any worker in the field. Few other works have subsequently reached the breadth and depth of information that Thiele had accumulated on the phylum Mollusca. The Handbuch was originally issued in four parts by Gustav Fischer was subsequently combined in two cloth-bound volumes and sold as a hard-cover edition. With Verlag in Jena. It each subsequent part after 1929, Thiele supplied extensive additions and corrections to the earlier text. As these additions and corrections have different dates of publication, they are included in this translation as footnote on appropriate pages rather than merged into the main body of the text. The third and final part of the English edition comprises 'Theile' 3 and 4 (the second volume of the original). The first three parts provide an indispensable resource for taxonomic The fourth work completed only a few months before his and anatomical research. part is death. the highlight of Thiele's Handbook of Systematic Malacology Parts 3 and 4 Handbook of Systematic Malacology Part 3 (Scaphopoda / Bivalvia / Cephalopoda) and Part 4 (Comparative Morphology / Phylogeny / Geographical Distribution) Johannes Thiele Scientific Editors of Translation: M. Mikkelsen Riidiger Bieler and Paula Smithsonian Institution Libraries Washington, D.C. 1998 TT 81-52005 Original edition: Johannes Thiele, Weichtierkunde, 4 in Handbuch der systematischen subsequently combined into 2 volumes, parts, 1929-1935. Gustav Fischer Verlag, Jena (now Translator: Dr. 1963 Stuttgart), S. Bhatti J. General Editor: Dr. V. S. Kothekar Library of Congress Cataloging-in-Publication Data Thiele, J. (Johannes), b. 1860, d. 1935. Handbook of Systematic Malacology. Handbuch der systematischen Weichtierkunde. Translation of: Translated by 1 I. . Mollusks — Bieler, Rudiger. QL406T4613 S. Bhatti. J. Classification II. — Collected works. Mikkelsen, Paula M. III. Title 594'.0012 1989 87-600185 Translated and published for the Smithsonian Institution Libraries, pursuant to an agreement with the National Science Foundation, Washington, D.C., by Amerind Publishing Co. Pvt. Ltd., 66 Janpath, New Delhi Typeset by Radiant Printers, Road Industrial Area, New 1 10 001, India New Delhi. Printed at Delhi 110 015. Baba Barkha Nath Printers, 26/7 Najafgarh Foreword The Smithsonian to the English-language Edition Institution Libraries, in cooperation with the National Science Foundation, has sponsored the translation into English of this and hundreds of other scientific and scholarly studies since 1960. The program, funded with Special Foreign Currency under the provisions of Public Law 480, represents an investment in the dissemination of knowledge to which the Smithsonian Institution is dedicated. Johannes Thiele (1860-1935) was one of the most productive systematists of his time. at the Between 1886 and 1935, Dresden Museum and published more than Thiele, who was originally based Museum in Berlin, Zoological later at the 150 scientific publications (for biographies and bibliographies, see Rensch, 1930, Winckworth, 1938, and Bieler number of 1989). Although a considerable and crustaceans, he known best is his & Boss, works dealt with sponges for his extensive contributions to malacology. These contributions range from smaller review articles to major monographs (e.g., VALDIVIA German Deep-Sea as part of the Expedition series) to handbooks that have become standards in the field Handbuch der of malacology. His probably best-known work, the systematischen Weichtierkunde (1929—1935) has become an indispens- Few able source of information for any worker in the field. other works have subsequently reached the breadth and depth of information that now Thiele had accumulated on the phylum Mollusca. His Handbuch systematic arrangement of taxa in the 'traditional' has been followed by thousands of workers and has become the basis for the arrangement of scientific collections throughout the world. Although outdated due to subsequent work, the Handbuch many is parts are still source of information and of great taxonomic significance as more anatomical data than the other major handbooks in work as part of the Handbuch der Paldozoologie, or Invertebrate Paleontology, and because taxa described by Thiele. reprinted in Workers its original less familiar translation services, To meet form and there that has not been translated of Mollusks at the National use, the likely hardly a at least comprises i.e., Wenz's on Treatise number of new demand, the Handbuch was & Co., Amsterdam). German language have had is it contains a large it the 1963 (by A. Asher in with the now an important page in the to resort to Handbuch once. Dr. Joseph Rose water, Curator Museum of Natural History in Washington, VI D.C., a initiated Handbuch, We request for a full English translation of Thiele's shortly before his untimely death in 1985. have verified and modified Thiele's original text has its this difficulties, translation word by word. such as awkward terminology and frequent ambiguous statements. Special care has been taken to retain these kinds of text problems, to provide a translation which as possible, while still furnishing readable copy. technical terms have been used A limited where Thiele employed is as literal number of common German terms without modern English equivalents, but no attempt has been made to update or correct the original, except in the case of the few obvious Many printer's errors in the text. lated to make them more geographical names have been trans- accessible to English readers; again, to remain we as close as possible to Thiele's concept of these places, modernize the names according 'Sippe' was used by Thiele to boundaries. political for taxa equivalent to the did not 'Stirps' or modern category superfamily. Because he frequently used non-standard endings (rather than -acea or -oidea) we used likewise informal we have Where we found a retained 'stirps' in the translation. endings for taxonomic group names informal ending in the translation (e.g., -aceans, -ids). In complex systematic or zoogeographical problems, or at any time when the English translation seems unclear, the reader is advised to refer back to the original Germany text for clarification. One problem with terminology deserves special mention here. Thiele's terminology for radular teeth was somewhat different from that in modern use. He referred to plates (Platten) instead of teeth (Zahne) and instances involving to teeth instead of cusps. His arrangement of central plate (Mittelplatte) and marginal or lateral plate most cases equivalent to the modern rachidian, lateral and marginal teeth, respectively. We have decided however to use the literal translations of the original terms, in order to avoid implications of homology not stated by Thiele, and to allow for the intermediate plate (Zwischenplatte), (Randplatte or Seitenplatte) is in possibility that a 'plate' does not necessarily carry a tooth-like structure. The Handbuch was originally issued in paperbacks by Gustav Fischer Verlag in Jena. four parts, It in orange was subsequently combined in two cloth-bound volumes and sold as a hard-cover edition. With each subsequent part after 1929, Thiele supplied extensive additions and corrections to the earlier text. The original Handbuch contains 24 pages of such additions. Another often-overlooked oddity of Thiele's work is the fact that he made major nomenclatural statements in the index and errata sections, such as the introduction of replacement names for homonyms subsequently discovered (see also Tomlin, 1936). As these Vll additions and corrections have different dates of publication, they are included in this translation as footnotes on appropriate pages rather than merged into the main body of the text. Throughout the text, the start of each original page as well original figure placement is signified by an original page number left margin. Names of new genera and have been printed in as the in the Handbuch species introduced in the boldface in the main body of the text and in the index (new names were unclearly indicated by spaced font in the A number of new taxa that were clearly introduced as such by Thiele but missed by the compiler of the original index have also been included. As in-depth account of Thiele 's publications and new genus-group taxa can be found in a series of papers by Bieler and Boss original index). (1989, 1991). As the dates of publication of the four original parts (Teile) are not readily obtainable from the hard-bound original volumes (Bande), a compilation of the dates follows below: Erster Band ("1931"): Teil (Loricata; 1. Gastropoda: Prosobranchia), pp. 1-376 (1929; published between 4 September and 22 October). (Gastropoda: Opisthobranchia and Pulmonata; Additions; Teil 2. Index for Teil 1-2), pp. 377-788 (1931; published before 1 November). Zweiter Band "1935"): (Scaphopoda; Bivalvia; Cephalopoda; Additions and Cor- Teil 3. 1-2; Index for Teil 3), pp. rections for Teile 779-1022 (1934; published before 20 January). (General Part and Corrections for Teile 1-3), pp. Teil 4. 1154, pp. i-vi (for Erster Band, divider pages for 1. and 2. Teil, unnumbered divider pages lished before 28 March). for 3. 1.-2. Teil), 1023- unnumbered pp. i-v for Zweiter Band, and 4. Teil (1935; pub- Literature cited: Bieler, R., & K. J. zoology. Part Boss. 1989. Johannes Thiele and his contributions to 1. Biography and bibliography. Nemouria, Occasional Papers of the Delaware Museum of Natural History, 34: 1—30. Boss, K. J., & R. Bieler. 1991. Johannes Thiele and his contributions to Genus group names (Mollusca). Nemouria, Occasional Papers of the Delaware Museum of Natural History, 39: 1—77. zoology. Part 2. Vlll Rensch, B. zum Johannes Thiele 1930. Molluskenkunde, 62(6): 201-209, Tomlin, R. J. B. le pi. Book 1936. 70. Geburtstage. Archiv fur 11. notes: Thiele's "Handbuch der Systematischen Weichtierkunde." Proceedings of the Malacological Society of London, 22(3): 136—137. Winckworth, R. 1938. Obituary: Johannes Thiele, 1860-1935. Proceedings of the Malacological Society of London, 23(1): 9—11. This Volume: This third and final part of the English edition comprises 'Teile' 3 and 4 (the second volume of the Teil 3 original). a continuation of the systematic treatment of the Mollusca, is covering Scaphopoda, Bivalvia and Cephalopoda (Aplacophora were not included Handbuch; the in Thiele, Solenogastres, did not consider first them who published extensively on part of the Mollusca). Whereas three parts provide an indispensable resource for taxonomic anatomical research, the fourth part is the and the highlight of Thiele's work. In completed only a few months before his death, Thiele this final part, on molluscan phylogeny and who had a nearcomplete overview of the known extant molluscan taxa based on personal work involving shells and anatomy. Certain of his hypotheses have been replaced by others it would, after all, be a major embarrassment to our field of science if we had not made some progress in the past 60 years. More recent evidence, for instance, no longer supports the position of the Pleurotomariidae as the most primitive living gastropods and the Patellidae summarizes in great detail He zoogeography. his thoughts probably was the last malacologist — as closely related with the Fissurellidae, but rather places the Patellidae as a much earlier offshoot of the gastropod clade. by Thiele based on in the Bivalvia now recognized as much of this work And the Juliidae, placed the then available shell characters, are highly derived bivalved gastropods. Nevertheless, remains surprisingly up-to-date, and much what he already inferred has been painstakingly rediscovered in subsequent decades. In the gastropods, for instance, this includes his statements about the special anatomical conditions and some of and systematic position of the neritaceans his hypotheses concerning the phylogenetic origin opisthobranchs. In the first part is reminiscent of a scala naturae: family A stands which then connects to family C. In the fourth part he mold and much of his concentration was placed on finding sequence that next to family broke this — management background — of the Handbuch, Thiele arranged his taxa possibly influenced by his strong collection in linear of the B IX morphological homologies. He carried it to the next level by often focusing on the distinction between primitive and special characters of the groups under study, foreshadowing in part today's cladistic approach to molluscan phylogeny. We hope that this pro-bono translation will make Thiele's work more widely known and accessible to malacologists world-wide. Riidiger Bieler Field Museum of Natural History Chicago Paula M. Mikkelsen American Museum of Natural History New York Contents Foreword to the English-language Edition Part 3 Orig. CLASS SCAPHOPODA 1. II. 2. Family Siphonodentaliidae Family Dentaliidae 781 III. IV. 1197 785 1201 1201 2. Family Malletiidae 785 786 787 3. Family Ledidae 788 1205 4. Family Solenomyidae 791 1209 791 1210 Stirps Nuculacea Arcacea 1202 1203 1. Family Arcidae 791 1210 2. Family Glycymeridae 1214 3. Family Limopsidae 794 794 Stirps Mytilacea Family Mytilidae Stirps Pteriacea 1214 1218 797 797 1218 797 1229 801 1224 801 1224 1. Family Vulsellidae 2. Family Pteriidae 803 1226 3. Family Pinnidae 803 1227 1. Family Dimyidae 2. Family Pectinidae 3. Family Limidae 804 804 804 809 Anomiacea 811 1239 812 1239 813 1241 813 1241 Stirps Pectinacea Stirps 1. V. 782 Family Nuculidae Strips 1. II. 1194 1. ORDER ANISOMYARIA I. 1195 1. 2. ORDER TAXODONTA I. Pg- 1193 779 780 CLASS BIVALVIA Transl. Pg- Family Anomiidae Stirps Ostreacea 1. Family Ostreidae 1228 1228 1229 1236 Xll 3. ORDER EULAMELLIBRANCHIATA SUBORDER SCHIZODONTA Stirps Trigoniaceae I. Family Trigoniidae Stirps II. 1. Unionacea Family Margaritanidae 2. Family Unionidae 3. Family Mutelidae 4. Family Aetheriidae SUBORDER HETERODONTA I. II. III. IV. V. VI. Stirps Astartacea 1. Family Astartidae 2. Family Crassatellidae Stirps Carditacea 1. Family Carditidae 2. Family Condylocardiidae Stirps Sphaeriacea 1. Family Corbiculidae 2. Family Cyrenoididae 3. Family Sphaeriidae Stirps Isocardiacea 1. Family Kellyellidae 2. Family Isocardiidae Stirps Cyprinacea 1. Family Cyprinidae 2. Family Libitinidae Cyamiacea Family Cyamiidae Family Sportellidae Family Neoleptonidae Stirps 1. 2. 3. VII. Stirps Gaimardiacea 1. 2. Family Gaimardiidae Family Juliidae VIII. Stirps Dreissenacea IX. Stirps Lucinacea 1. 2. X. Stirps Erycinacea 1. 2. XL Family Ungulinidae Family Lucinidae Family Erycinidae Family Montacutidae Stirps 1. Chamacea Family Chamidae 814 814 1243 815 1243 815 1244 1242 815 1244 816 816 837 843 844 844 844 845 847 847 849 850 850 852 852 854 1245 854 855 855 855 856 857 857 859 860 860 1245 1275 1282 1284 1284 1284 1286 1288 1288 1291 1293 1293 1295 1296 1298 1298 1300 1301 1301 1301 1303 1303 1306 1307 1309 861 1309 862 862 863 863 865 869 869 874 877 877 1310 1311 1312 1312 1315 1321 1321 1329 1332 1332 Xlll XII. Stirps Cardiacea Family Petricolidae 895 Veneracea II. 1359 1359 Family Maetridae 3. 904 1371 4. Family Cardiliidae 905 1371 905 1372 Stirps Tellinacea 1362 1. Family Donacidae 905 1373 2. Family Psammobiidae 1375 3. Family Semelidae 908 911 4. Family Tellinidae 913 920 920 1380 1384 1393 1393 1. Family Glaucomyidae 920 1393 2. Family Solenidae 921 1394 1398 Stirps Saxicavacea 3. Family Pandoridae Family Myochamidae 4. Family Chamostreidae 5. Family Pholadomyidae 6. Family Thraciidae 923 924 925 925 926 928 928 929 929 933 936 936 936 937 938 938 939 939 7. Family Laternulidae 941 1422 942 942 1425 Family Saxicavidae Stirps Myacea 1. Family Aloididae 2. Family Myidae Stirps Gastrochaenacea Family Gastrochaenidae Stirps Adesmacea 1. Family Pholadidae 2. Family Teredinidae SUBORDER ANOMALODESMATA I. 896 Family Anatinellidae 1. V. 1341 1341 2. 1. IV. 1340 896 898 Stirps Solenacea III. 1357 2. Family Tridacnidae SUBORDER ADAPEDONTA II. 1334 Family Veneridae 2. XIV. Stirps Mactracea 1. Family Mesodesmatidae I. 1333 1. Family Cardiidae XIII. Stirps XV. 877 878 882 883 883 1. Stirps Pandoracea 1. Family Lyonsiidae 2. Stirps Clavagellacea Family Clavagellidae 1398 1400 1400 1402 1404 1404 1406 1406 1411 1415 1416 1416 1417 1418 1419 1419 1420 1425 XIV III. Poromyacea Family Verticordiidae 943 943 1426 1. 2. Family Poromyidae 945 1430 3. Family Cuspidariidae 946 948 949 1431 951 1436 951 1436 952 953 1439 953 954 1441 Stirps CLASS CEPHALOPODA SUBCLASS TETRABRANCHIA I. Family Nautilidae II. SUBCLASS DIBRANCHIA I. ORDER DECAPODA I. II. III. II. Stirps Sepiacea 1. Family Spirulidae 2. Family Sepiidae 3. Family Sepiadariidae 4. Family Sepiolidae 5. Family Idiosepiidae Stirps Loliginacea 1. Family Loliginidae 2. Family Lepidoteuthidae 3. Family Promachoteuthidae 955 955 959 1426 1433 1435 1439 1439 1443 , 1444 1448 958 958 960 1448 1450 1448 1450 1. Family Lycoteuthidae 960 960 960 2. Family Enoploteuthidae 961 1453 3. Family Octopodoteuthidae 1456 4. Family Neoteuthidae 963 964 5. Family Onychoteuthidae 6. Family Gonatidae 7. Family Psychroteuthidae 8. Family Architeuthidae 9. Family Histioteuthidae Stirps Architeuthacea 1451 1451 1457 10. Family Alluroteuthidae 11. Family Bathyteuthidae 964 967 967 968 968 970 970 12. Family Brachioteuthidae 971 1467 13. 971 14. Family Valbyteuthidae Family Ommatostrephidae 1467 1468 15. Family Thysanoteuthidae 16. Family Chiroteuthidae 17. Family Joubiniteuthidae 18. Family Cranchiidae ORDER OCTOPODA Suborder Cirrata Stirps 1. Vampyroteuthacea Family Vampyroteuthidae 971 974 974 977 977 983 983 983 983 1457 1461 1462 1462 1463 1465 1466 1471 1472 1476 1476 1484 1484 1485 1486 XV 2. Family Laetmoteuthidae Stirps Cirroteuthacea II. 985 1488 2. Family Cirroteuthidae 1489 3. Family Opisthoteuthidae 985 987 987 987 988 988 988 989 989 993 993 993 994 994 995 1491 1. Family Bolitaenidae 2. Family Amphitretidae 3. Family Vitreledonellidae Stirps 1. Octopodacea Family Octopodidae Stirps III. Argonautacea 1. Family Alloposidae 2. Family Tremoctopodidae 3. Family Ocythoidae 4. Family Argonautidae Additions and Corrections to Parts 1 1488 Family Stauroteuthidae Stirps Bolitaenacea II. 1488 985 1. SUBORDER INCIRRATA I. 985 and 2 (Volume 1489 1491 1492 1492 1493 1494 1494 1499 1500 1500 1501 1502 1502 1) Alphabetic Index of Genera, Subgenera and Sections Mentioned 1011 1503 1023 1531 in Part PART 4 Fundamentals of the Natural System of the Mollusks Outline of the Phylogeny of the Mollusks 1073 1593 Paleontology and Phylogeny 1122 1652 Geographical Distribution of the Mollusks 1127 1658 Of 1150 1687 1152 1688 1154 1690 the Nomenclature of the Mollusks Literature on Mollusks Corrections PART 3 Scaphopoda/Bivalvia/Cephalopoda 1193 ClassrSCAFHOPODA 779 more or Shell bilaterally symmetrical, exteriorly smooth or ribbed, open completely enclosed by the shell. at most cases less elongated, in weakly curved, tube- or spindle-shaped, as a rule posteriorly narrowed, both ends. The animal in repose The mantle is is ventrally closed and, with the body, forms an anteriorly and posteriorly open tube, the posterior part of which forms a shovel-shaped appendage. The head without eyes, opening, at its with a an oral cone is of lobe-shaped appendages rosette at the oral base are found a pair of small skin folds, from which arise several long, terminally thickened, extensile cirri (captacula). produced, distensible foot serves in burrowing. is The nervous system in bivalves, but differs in the The anteriorly protruded from the anterior opening and is of similar arrangement to that presence of buccal ganglia. Gills are absent; instead of these, the function of respiration may be performed by the mantle and an organ (aquatic lung) consisting of several finger-shaped tubes on the rectum. The oral tube leads into a buccal mass, which contains a horseshoe-shaped jaw, a radula, the rows of which consist of five plates, and a subradular sense organ as esophagus has a wide glandular sack on either Loricata; the short side; the digestive gland in opens into the loop-shaped stomach; the coiled intestine opens into the mantle cavity behind the foot. The somewhat lobed kidney sacks lie beside the rectum, without connection with one another and with the pericardium; they open somewhat behind the anus. The heart auricles; it is rudimentary, without consists of a dorsal invagination of the pericardium, true blood vessels are absent; the blood sinus surrounding the rectum with the mantle cavity by 1 pair of small cleft-shaped pores. is connected The sexes are separate, special exit ducts and copulatory organs absent; at the time of maturity, the gonad fuses with the cells are released into the right kidney, through which the germ mantle cavity, from where they are expelled through the posterior opening by contraction of the animal. The scaphopods their foot, so that in their most cases and burrow into the substratum with end alone projects out; food consists of small organisms, mainly foraminiferans. The only live in the sea in their posterior posterior end of the shell corresponds to the embryonic shell very young animals; later frequently shows indentations or a perforations. it is repeatedly truncated and then more or less long slit or a series of 1 194 1. 780 Shell more or Family SIPHONODENTALIIDAE less small, smooth, colorless, often narrowed at the worm-shaped or with a disk-shaped, denticulate terminal disk, in the center of which a finger-shaped process occasionally is situated; the anterior end of the foot is introvertible; the central plate of the radula is a cutting-edge-less plate, which is about as long as broad; the intermediate plate forms a fairly strong, somewhat cuspidate, medially anterior end. Foot simply directed cutting edge; the marginal plate broader than long, without is cutting edge. Cadulus Philippi, 1844 more or Shell circular or oval in cross section, less swollen in the center or nearer the narrowed anterior end. Several species in various seas. Section Cadulus s. s. Shell short, distinctly swollen in the center, spindle-shaped; both openings simple, the posterior one with an interior thickening of the margin. — Section Gadila Gray, ovulum Philippi (Fig. 784). 1847 (synonyms Helonyx Stimpson, 1865; C. (C.) GadUs (Rang, 1829) Conrad, 1866, non Linne, 1758; Loxoporus Jeffreys, 1869). Shell more or less slender, curved, dorsally concave, somewhat swollen in the center or nearer the anterior end; margin at the posterior without callous thickening and without incisions. C. (G.) gadus (Montagu). — Section Dischides Jeffreys, either side with a 1867. Shell fairly slender, posteriorly on deep incision. C. (Z).) politus (S. Wood). — Section Platyschides Henderson, 1920. Shell posteriorly with 2 or 4 very shallow indentations. Sharp, C. 1898. incisions, (Watson) (P.) Shell grandis Verrill. posteriorly with which divide the margin (Fig. — Section Polyschides into lobes. C. (P.) 785). Fig. 784. Shell of Pilsbry & a few, in most cases 4, distinct Cadulus cyathoides Jaeckel. Length about 3 mm. tetraschistus 1195 Fig. 785. Shell of Cadulus (Polyschides) tetraschistus (Watson) var. quadridentata (Dall). Length nearly cm (after Pilsbry). I Siphonodentalium M. Sars, 1859 Synonyms Siphonodontum + Tubidentalium Locard, 1886. Shell curved, nearly or completely circular in cross section, smooth, widest opening; posterior end with or without incisions; at the anterior foot with a disk-shaped thickening. Few species, mostly in the deep sea. Section Siphonodentalium s. without finger-shaped process. Pulsellum Stoliczka, Shell s. S. Shell (S.) with posterior incisions; foot lobatum (Sowerby). — 1860 (synonym Siphonentalis G.O. Sars, Section 1878). without posterior incisions; foot with a finger-shaped process. S. (P.) lofotense M. Sars. Entalina Monterosato, 1872 Shell widest anteriorly, in the posterior part strongly ribbed, angulate. Foot as E. in Pulsellum with a finger-shaped process. quinquangularis (Forbes). 781 2. Family Few species in various seas. DENTALIIDAE Shell elongated, curved, smooth or ribbed, widest anteriorly. Foot not introvertible, on either side with a lobe near the end; central plate of the radula about twice as broad as long (Fig. 786). Fig. 786. Half radular row of Dentalium octangulatum Donovan. 1196 Dentalium Linne, 1758 Characters of the family.. Numerous species in The genus is divided partly unknown. seas. all into a few groups, the anatomy of which Section Compressidens Pilsbry D. (C.) pressum & Sharp, 1897. Shell small and thin, without posterior dorsoventrally compressed, nearly smooth, & Sharp Pilsbry. — is Section (synonym Pseudantalis Monterosato, 1884). Fustiaria Shell Stoliczka, slit. 1868 smooth or with regular annular furrows; oral opening circular; posterior opening round or oval, with a very long slit on the ventral — Section Bathoxiphus Pilsbry & side. Sharp, 1 C. (F.) circinatum Sowerby. 897. Shell nearly or completely smooth, laterally compressed, posteriorly with a broad ventral D.(B.) ensiculus Jeffreys. — Section Episiphon Pilsbry & Sharp, slit. 1897. Shell small and very slender, only slightly curved, thin, smooth, posteriorly sometimes with a small tube-shaped prolongation, without slit. Section Rhabdus Pilsbry & Sharp, 1897. Shell scarcely curved, very thin, smooth and shiny; both openings Section Laevidentalium Cossmann, simple. D. (R.) rectius Carpenter. 1888. Shell of moderate to considerable size, smooth, round or somewhat oval; posterior end in most cases simple, occasionally with a short Section Graptacme ventral indentation. D. (L.) incertum Deshayes. D.{E.) sowerbyi Guilding. — — — Pilsbry furrows sized, & Sharp, 1897. Shell with fine, dense, deeply incised, longitudinal at the posterior semistriatum Turton. ribs end or throughout the length, small or mediumwith incisions. D. posteriorly sometimes cylindrical, — Section Dentalium s. (G.) Shell ribbed or angulate; s. often posteriorly strengthened; posterior end without D. (D.) slit. elephantinum Linne (Fig. 787). Co ceo dentalium Sacco, 896, is distinguishable by the presence of ring-shaped ribs or lamellae. D. (C.) radula Schroter |. Section Tesseracme Pilsbry, 1894. Posterior end 1 — — & Section Antalis H. A. quadrangular. D. (J.) quadrapicale Sowerby. Adams, 1854 (synonyms Entalis Gray, 1847, non Sowerby, 1839; Fig. 787. Dentalium elephantinum Linne. Length about 8 cm. 1197 Entaliopsis young Newton & Harris, 1894). Shell cylindrical or angulate, in the permanently with longitudinal ribs or state or posteriorly striae, with an angular indentation or a small short tube. D. (A.) entalis Linne. — Heteroschisma Simroth, Section posteriorly with a dorsal Fissidentalium slit. 1894). Shell large and strong, with simple or with a long 782 Fischer. P. A longitudinally ribbed, Shell — Section 1885 (synonym Schizodentalium Sowerby, Fischer, P. 1895. D. (H.) subterfissum Jeffreys. many longitudinal ribs, posteriorly or a series of perforations. D. (F.) ergasticum slit few species mainly in the deep sea. ClassBIVALVIA The bivalves (Bivalvia, Acephala, Pelecypoda) are as a rule bilaterally symmetrical mollusks, the shell of which consists of 2 lateral halves, which are nearly always articulated with one another by an elastic ligament and in most cases enclose the entire animal. The form of the shell shows important variations; in most cases it is more or less compressed and transversely oval, sometimes roundish or higher than long; on the other hand, it occasionally greatly elongated; the anterior is and posterior ends are often distinctly dissimilar, is pointed, the latter not seldom truncated. or more or there may be a rule sometimes the former exterior side less distinctly sculptured; besides the concentric identical or radial lines, mirror images or only slightly dissimilar, but are when substratum or smooth ribs, sometimes strikingly unequal, especially when one valve the is growth seldom oblique ridges, or thorns or long spines. The two valves are stronger rings sometimes also small scales as The is attached to asymmetrically from the the byssus emerges shell. are The beaks (umbones), from which the growth of both valves begins, seldom far apart from one another, resulting in a broad dorsal surface; in most cases they posterior halves; the lie former close together, separating the anterior and is escutcheon; one or both of these lateral known as lunule, the latter as may be distinctly delimited from the then parts. The ligament joining the two valves external, sometimes partly or completely is sometimes completely internal. When ligament continues anteriorly between the umbones, amphidetic; is it umbones. The or may In most cases when it lies completely ligament may be continuous with opisthodetic internal be separated from the it on the more or is latter; it is is the external said to be posterior to the the external one called the cartilage (resilium). below the umbones, often it is borne downwardly projecting processes of the dorsal short, situated less large it 1198 margins. Occasionally Adesmacea alone, of the rough it contains a calcified part (lithodesma). which bore into solid structures shell valves, is the ligament most cases the completely reduced, so that the by muscles. valves are joined together only In In by rasping movements shell is able to enclose the entire gaping. However, in byssate mussels a narrow cleft, animal without seldom an asymmetric remains open for emergence of the byssus. In very few indentation, groups the shell remains wide open on the ventral end gapes more or large siphons, the posterior which as in Pinna, side. If the mantle has much less broadly, very sticks into the substratum with its pointed anterior end. The two valves, which is as a rule expanded most cases supplied with tooth-shaped processes dorsal margin of the into a hinge plate, is in fitting into one another; such hinge teeth more or less large number of which are usually transversely disposed, but in taxodonts, a present, is occasionally the outer ones are arranged obliquely or parallel to the margin. In heterodonts, the number of teeth 783 the umbo of numeral 1 ; the right valve fits it into both, in most cases separated, halves of an arch- two branches of lamella lamella 4 of the may be reduced; the tooth below designated as the central tooth with the shaped, lamellar-tooth-structure of the the is is left valve 3 left of the valve (2), which reduced, such as the posterior branches, when shells, it is is the ligament may be of teeth is anterior margin. Occasionally there are lateral teeth parallel to the tooth-like structures of another kind. In some, in the hinge margin joined by most cases absent. Some of these is in sunken. Besides these teeth, called cardinal teeth, there and posterior is right valve; the anterior half most cases small, transversely finely grooved, shells, and, mainly in thin smooth. The inner surface of the shell more or less distinctly shows the scars of muscle attachments, of which those of the adductor muscles are the most conspicuous. In most cases, 2 of them are present, one anterior and one posterior; however, in various groups the anterior one has become diminished or completely reduced, whereas the posterior one has closer to the center of the shell. close the shell, but in outward from the therefore its Adesmacea interior, rule these come two muscles together the anterior one has and attaches become displaced to an outwardly reflected part; contraction results in gaping of the posterior part of the shell, antagonistic to contraction and As a retractors of the posterior muscle. The protractors of the foot attach on the dorsal part of the inner side. Running parallel to the lower shell margin is the so-called pallial line, at which the musculature of the mantle edge attaches; it is seldom interrupted and is indicated by a series of punctures. In bivalves with 1199 large more or siphons, pallial the at has acquired an embayment, the line pallial sinus (sinupalliates). The broad mantle folds, interiorly covering the lateral parts and bringing about shell elongated retractors are formed, less attachment of which the of the growth, primitively have free margins its throughout their length, which are sometimes provided with tentacles or eyes. Parts of the two margins are often fused posterior end where an together, mainly at the upper, excurrent opening is separated from a lower one, and on the ventral side where a more or less large opening of the foot for protrusion from the posterior incurrent separated is opening. The two posterior openings are often produced into more or less long tubes (siphons), which remain separate or fuse with one another. Occasionally they reach considerable length, so that they greatly surpass the body covered by the Sometimes they have a membranous or shell. calcareous covering; such a calcareous tube either remains separate from the shell or fuses with one valve or with both; in Brechites the shell has become rudimentary as a result of such Because the body of bivalves is as a shell, in a fusion. rule completely enclosed a distinctly recognizable head has few groups, small cup-shaped eyes are present end of the inner gill lamina; these by the become reduced. Nevertheless in front may be homologous eyes of snails. Besides these and the sense organs of the anterior with the cephalic at the margin of the mantle and the siphons, statocysts are developed, which in some groups connect with the surface of the body by fine canals and contain small sand grains instead of statoconia or statoliths; there are also epithelial sense organs (osphradia, abdominal and adoral sense organs). The body epithelium has glandular 784 structures in various places, such as often in the posterior part of mantle cavity, at the mantle margin, or occasionally also on the inner side of the mantle lobes, as in Lithophaga, in which an acidic secretion for boring developed into produced by a gland, used by the animals is limestone rock. The skin glands are most strongly in the foot, the ventral surface of which is often pulled into a groove anteriorly, a deeper groove posteriorly, and produces a secretion (byssus) that hardens, by which the animals attach themselves to solid substrata. The muscular which by swelling, assumes various which is nevertheless not a creeping sole; the sole corresponds with the byssus cavity, which however is very often reduced. In most cases the foot is hatchet-, tongue-, or forms; it foot, seldom has a finger-shaped, is protrusible distinct sole as in snails, more seldom very small or completely pestle- lost. or worm-shaped; occasionally it is 1200 The mouth opening of bivalves lies at the base of a groove, formed by an anterior and a posterior lip, which continue on either side into more or less broad lobes (oral lobes or palps), the sides of which facing one another are as a rule beset with transverse ridges; in most cases they extend to the anterior end of the gills. In Lima species the two lip margins are fused together, forming a tube open become rudimentary. the labial palps have long process on either side, which The in gills in zeugobranch leaflets. As both ends. Sometimes at In nuculaceans they have a groove-shaped on one is side. nuculaceans and Solenomya have a form similar to those snails, each consisting of an axis with 2 rows of short a rule these leaflets have become attenuated to form long filaments which are flexed outward, so that each filament has the filaments altogether forming 2 lamellae on either side. by brush-like cilia; which then filaments are initially joined to one another only moreover, there are often firm fusions, mainly at their ends, enclose a longitudinal exit vessel. Further fusions between successive filaments but also between each gill may their has the appearance of 2 lamellae pierced by the rows of filaments exterior edges become may become plicated, take place not only two limbs, so clefts. In and the filaments completely. When visceral sack it that other groups in the interior and very large (border filaments). Sometimes the exterior gill lamella is distinctly smaller than the interior; upwardly directed; two limbs, The successive may form it only a simple lamella or is occasionally may disappear the free margins of the interior lamella fuse with the and posterior to it with one another, those of the exterior lamella with the mantle, the mantle cavity is divided into a lower and an upper chamber; water entering the lower chamber passes into the upper chamber through the gill clefts and then to the exterior through the excurrent opening. In the Poromyacea, the gill lamellae become narrowed assume the form of small sieves or rows of simple pores in the horizontal septum. Bivalves seldom have accessory gills, as small folds over the upper margin of exterior lamella, or as folds of the partition and finally extending between the two gills behind the foot, or as folds on the interior side of the mantle. The central nervous system of bivalves as a rule consists of 3 pairs of ganglia, the cerebropleurals, pedals, and viscerals. The first in most cases lie in front of or beside the esophagus; in Lima they are displaced 785 far backward and are close to the viscerals, to which they are always connected by the visceral commissure. Below these palpal ganglia, which mainly innervate the lie labial sometimes small palps. The pedal The ganglia are also joined with the cerebropleurals by connectives. visceral ganglia supply the gills, the posterior adductor muscle, and the major part of the mantle margin, and, especially when sense organs are present, may be strongly developed on the latter. 1201 Along with the head, the buccal mass the short, digestive A shaped stomach. initial part less coiled; is more or terminal part runs above the posterior adductor muscle, its opens it most cases with an anal in most cases is is The pedal sinus papilla. similar to that of zeugobranch snails; the by the traversed is or below the latter and auricles. is gelatinous structure (crystalline style) sticks into the heart of bivalves ventricle in also reduced; the foregut of the intestine or into a blind sack; the intestine below which The is gland often opens asymmetrically into the sack- intestine, seldom lying above very seldom symmetrically paired as are the is separated Ifrom a sinus lying below the kidneys by a closable, sometimes paired opening (Keber's valve) which A allows the swelling of the foot. of the posterior muscular thickening aorta, in siphonate bivalves separated by a valve, serves at the beginning from the ventricle for swelling of the siphons. The pericardium, which only in some Area species consists of two completely separated, symmetrical halves, has glandular epithelium various places. It is have the basic form of a two-limbed tube, with and excretory The coiling. In at connected to the surface by 2 kidney ducts, which distal limb; the glandular area proximal limb ciliated may increase by folding or primitively completely separated ducts frequently join together. most cases bivalves have separate sexes, although hermaphroditism The gonads has developed in various groups. lie paired symmetrically in the visceral sack, occasionally they extend into the mantle. Their exit ducts are nearly always short and simple, and as a rule open next to the kidney openings; copulatory organs are always absent. Occasionally there in is brood care, wherein the eggs develop inside the mantle cavity, most cases within the The phylogenetically gill laminae. oldest bivalves are the taxodonts, originating from which on the one hand are the anisomyarians with margin and open mantle, and on the other the long series straight hinge of groups which nearly always have 2 adductor muscles, and in which often more or less long siphons are developed. 1. Order TAXODONTA Hinge margin with more or less numerous, identical teeth; nearly always 2 adductor muscles present. I. STIRPS NUCULACEA Shell roundish to elongated; ligament sometimes completely external, sometimes with internal cartilage. Hinge margin more or less arched or 1202 angulate, as a rule with several small teeth; mantle open or with posterior 786 siphons; gills with 2 rows of short leaflets; foot with a broadened and scalloped terminal suited disk, for burrowing, without byssus; labial palps on either side with an in most cases long tentacle-like appendage. NUCULIDAE Family 1. Shell nacreous, trigonal to oval; posterior part shortened, not gaping; hinge margin angulate, the ligamental cartilage two limbs, in most cases more or less is sunken between the interiorly projecting. completely open, without siphons; foot ventrally directed; anteriorly and ventrally; open, with sand grains; labial Mantle gills directed palp tentacles fairly large; statocysts kidneys fairly short, with two limbs, lobed, connected with one another; apertural part communicating with the pericardial funnel and with the gonoduct. Nucula Lamarck, 1799 Synonym Nuculana Link, 1807. Characters of the family. The genus includes numerous Subgenus Brevinucula short trigonal, exteriorly n. species distributed in all seas. subgen. Shell small and relatively strong, smooth and shiny; hinge margin strongly angulate, the small ligamental cartilage not or only slightly interiorly projecting and separating the anterior and posterior tooth rows; posteriorly the shell flattened. N. (B.) guineensis Thiele (Fig. 788). coasts and on the east coast Few of North America, is species on the African in the deep sea. Subgenus Lionucula W. Quenstedt, 1930 (Leionucula) (synonym Ennucula Iredale, 1931). Shell small to medium-sized, in most cases fairly thin, roundish to oval, exteriorly smooth; the ligament projects obliquely forward below the hinge margin and above teeth of the anterior row; the structure N. (L.) albensis Orbigny t; Fig. 788. many is it lie the posterior uniform without radial trabeculae. living species in various seas. Hinge margin of Nucula (Brevinucula) guineensis Thiele, enlarged. 1203 Subgenus Acila H. & A. Adams, 1858. Surface of the more or less strong shell with anteriorly and posteriorly diverging or zig-zag-shaped ridges or rows of tubercles, which sometimes appear somewhat serrated hinge margin and ligament as in Lionucula. Section Gale, 1931. Shell posteriorly not beaked. N. (T.) Truncacila Grant Section Acila s. s. Shell posteriorly short beaked. castrensis Hinds. at the margin; & — Hinds. N. (A.) divaricata Subgenus Nucula s. Exterior shell layer formed of peculiar radial s. prism-like trabeculae, which are interiorly overlain with nacre and at the margin project as small denticles; surface in most cases smooth, sometimes distinctly concentrically or characteristically sculptured; the ligament is similar in most cases to that in Lionucula, in small species only slightly 787 or not inwardly projecting {Pronucula Hedley, (Linne) (Fig. 789). Several species in Fig. 789. Internal side 786 Deminucula of the Iredale, Just as Verrill left shell 902). N. (N.) nucleus valve of Nucula nucleus (Linne), enlarged. 1931, does not seem to be different. and Dall have assumed, not propose Nuculana as a the 1 all seas. new I have no doubt that Link did genus, but had only somewhat changed Lamarkian name. Family 2. MALLETHDAE Shell roundish or longish, sometimes posteriorly truncated or pointed, not nacreous; hinge margin not distinctly angulate, with numerous pallial teeth; ligament sinus absent in more or less completely external; an incurrent siphon and a Tyndaria. Statocysts open, with sand gains. Tyndaria Bellardi, 1875 (Tindaria) Shell roundish or oval, elevated, in most cases smooth or concentrically sculptured; umbo situated a little in front of the center; pallial line 1204 without indentation; mantle open ventrally, only an excurrent aperture differentiated with marginal papillae, without siphons. A few species, mainly in the deep sea. Section Pseudoglomus 1896. Dall, Shell smooth, roundish; thin, ligament short, somewhat sunken; hinge margin with few teeth separated by a small space. T. (P.) pompholyx (Dall). Section Tyndaria s. s. Shell — most cases strong, concentrically sculptured; hinge margin with oval, in which are continuous or with short teeth several arata Bellardi f. Protonucula Cotton, 1930, is interruption. T. (T.) not substantially different from Tyndaria. Neilonella Dall, 1881 Synonyms Saturnia Seguenza, & Verrill Shell 1 877 (non Schrank, 1 802); Tindariopsis Bush, 1897. exteriorly concentrically sculptured, anteriorly rounded, indentation; posteriorly angular; small fairly line pallial and strong, with a small siphons short, ventrally open and openly joined with one another. N. corpulenta (Dall). A few species, mainly in deep water. Malletia Desmoulins, 1832 Synonyms Solenella Sowerby, 1832; Ctenoconcha Gray, 1840. Shell most cases longish, posteriorly rounded fairly thin, smooth or pallial line distinctly indented; medium-sized, in or truncate, striated; tooth row with short interruption; animal with long, closed and completely united siphons. A few species in cold or deep water. Subgenus Minormalletia Dall, 1908. Shell longish, fairly small, posteriorly row interrupted. rounded; umbo M. (M.) arciformis thin, smooth, situated in front of the center; tooth Dall. Few species on the west coast of Central America. Subgenus Neilo H. & A. Adams, 1854. Shell posteriorly truncated, with an edge descending posteriorly from umbo and an indistinct beak; surface sometimes distinctly concentrically sculptured, sometimes fairly smooth or with weak, somewhat oblique furrows; umbo situated somewhat in front of the center; hinge margin well-developed, with numerous small teeth. 788 M. (N.) australis Subgenus Malletia (Quoy & Gaimard). s. (synonym Pseudomalletia s. P. Fischer, 1887). Shell posteriorly rounded or blunt, without sculpture; hinge margin short, in front of the umbones with few small teeth. M. (M.) chilensis Desmoulins. 1205 LEDIDAE Family 3. Shell not nacreous, transversely oval or more or less elongated, often hinge margin more or less angulate, denticulate; posteriorly pointed; ligament with a smaller or larger cartilage between the teeth; mantle with posterior siphons and a tentacle; closed, with palp tentacles long; labial statocysts kidneys tube-shaped, anteriorly directed, inter- a statolith; connected and emptying together with the gonoducts. A. Subfamily Sareptinae Shell small, thin, transversely oval, smooth or concentrically striated; ligament with sunken or interior cartilage; hinge margin in most cases fairly short; animal without siphons. & Microyoldia Verrill Shell small, transversely oval; Bush, 1897 umbo situated somewhat in front of the center; ligament with a relatively large cartilage on the upper side of the hinge margin somewhat posterior to the umbones; fairly strong, hinge margin arched. M. regularis (Verrill), on the North American east coast. Pristigloma Dall, 1900 Synonym Glomus Jeffreys, 1876, Shell small, roundish; umbo at non Gistel, 1848. or near the center; ligament elongated and posteriorly extending from the umbones the posterior tooth row; hinge margin fairly P. nitens (Jeffreys). Few species in the to below the beginning of weak and in most cases short. North Atlantic, near the West Indies and Japan. Sarepta A. Adams, 1860 Synonym Ovaleda Iredale, Shell transversely oval; 1925. umbo situated in the center, projecting; ligamental cartilage situated the two halves of the small S. weak and below umbones, only slightly short, between short hinge margin, which bears a few denticles. speciosa A. The hinge of genus Ovaleda, is Adams S. (Fig. 790). Few species in the Pacific Ocean. tellinaeformis Hedley, for which Iredale proposed a so similar to the typical species that belongs to the same genus. it undoubtedly 1206 Fig. 790. External and internal side of a shell valve of Sarepta speciosa A. Adams, enlarged. B. Subfamily Ledinae Shell more or less elongated and posteriorly rostrate; ligamental cartilage not closely joined with the external ligament; animals as a rule with pallial indentation and with siphons. Ledella Verrill 789 & Bush, 1897 Synonyms Junonia Seguenza, 1877, non Hubner, 1816; Comitileda Iredale, 1924. Shell small, transversely oval, in most cases smooth, with small, most cases somewhat blunt rostrum which indentation; area not sunken; cartilage in is set in off below by a shallow most cases small, but distinct; siphons separate. A few species in various seas. Magaleda Iredale, 1929, for Leda inopinata Edg. Smith, by the presence of a few differs only radial ridges. Phaseolus Monterosato, 1875 Shell very small, transversely oval, smooth; hinge margin with few denticles parallel to the margin. P.>ovatus Seguenza (Fig. 791), in the Mediterranean Sea and Ocean. Atlantic 1207 79 Fig. 1 External and internal side of a shell valve of Phaseolus ovatus . Seguenza, enlarged (after Seguenza). Leda Schumacher, 1817 with Shell a more or less sometimes pointed, sometimes long, truncated rostrum, as a rule concentrically sculptured; ligamental cartilage situated short, directed; below the umbones, sometimes obliquely posteriorly siphons partly or completely fused with one another. Numerous species in seas. all Section Jupiteria Bellardi, 1875 (synonyms Ledina Sacco, 1898, non Dall, 1898; Saccella most cases Woodring, 1925; Teretileda fairly small, inflated, with Iredale, 1929). Shell in concave above, exteriorally more or distinctly less living species.—Scaeoleda Iredale, scarcely different; the concentric sculpture below the rostrum. — is straight (L. is distinct Bronn f. crassa Hinds) is and forms an edge 1908. Shell smooth, with a Section Spinula Dall, pointed rostrum, which 1929 is concentrically sculptured; ligamental cartilage not elongated. L. (J.) concava Several which short, pointed rostrum, above and distinctly demarcated below; ligamental cartilage triangular; siphons long, completely fused, without pallial indentation; without labial palp tentacles. L. Dall, 1 on the east coast of South America. — (S.) calcar Section Lembulus Risso, 826. Shell with oblique sculpture and short rostrum, delimited below by an edge, straight above. L. (L.) pella (Linne), in the Mediterranean Sea and Atlantic Ocean. — Section Leda 1929). Shell with a more or more or distinct with less concentric ligamental cartilage straight or 790 (Fig. 792). A few species scarcely different; somewhat in various rostrum long. (synonym Thestyleda sculpture; Iredale, at the end, and hinge teeth angular; oblique. L. (L.) pernula (Mttller) seas. Poroleda Tate, 1893, Propeleda Iredale, is 1924 Shell with long rostrum, truncated end, with obliquely posteriorly ingressing ligamental cartilage, and thin hinge teeth Angas. s. —Section (synonym Lamellileda Cotton, 1930). at the s. long rostrum, truncated less Few which are almost parallel to the margin. L. (P.) ensicula species in the southern seas. 1208 Fig. 789 792. Shell of Leda pernula (Muller) after Sars. Silicula Jeffreys, Shell elongated, compressed, thin; umbo close to the rounded ligament obliquely ingressing; hinge anterior end; posterior end blunt; margin with few teeth which are 1879 parallel to the margin; pallial indentation broad, moderately deep. Few S. fragilis Jeffreys. near Patagonia. This group species in the northern Atlantic is Ocean and probably related to Propeleda, and may only deserve the rank of a section. Portlandia Morch, 1857 Shell small to medium-sized, in completely closed; umbo most cases with smooth periostracum, most small, close to the center; outline oval, in cases with short rostrum which demarcated by a shallow indentation; is ligamental cartilage situated below the umbones; hinge margin not very long; siphons largely fused. A ? few species, mainly Subgenus Adranella trically striated, oval, in cold seas. & Verrill Bush, 1898. Shell small, concen- somewhat broadened, not posteriorly hinge margin fairly strong. P. (A.) casta (Verrill Subgenus Yoldiella Verrill indentation more or less shallow. & Bush, 1897. & rostrate; Bush). Shell P. (Y.) lucida Loven. small; pallial 1209 Subgenus Portlandia (P.) arctica P. distinct. s. medium-sized; Shell s. indentation pallial (Gray). Yoldia Moller, 1842 Shell in most cases and fairly large umbo or weakly sculptured, gaping; flat, more or less elongated, smooth close to the center, only slightly projecting; external ligament weak; cartilage more or less projecting interiorly; indentation deep. Mantle with long, fused siphons and a long pallial posterior tentacle. Several species in various seas. Section Katadesmia Dall, 1908. Shell smooth and shiny, moderately elongated; umbo somewhat situated anterior to the center, posterior end with a short, rounded point; external ligament situated posterior to the umbones; cartilage trigonal. Y. (K.) vinculo Dall, on the west coast of Central America. — Section Megayoldia Verrill & Bush, 1897. Shell posteriorly broadly truncated; external ligament anterior and posterior to umbones; the strong. cartilage species in the northern seas. Shell elongated, Few Dall. anteriorly Y. — (M.) thraciaeformis (Storer). Section Orthoyoldia Verrill and posteriorly rounded. America and species near Central Brazil. — Y. & Few Bush, 1897. (0.) scapania Section Yoldia s. s. Shell smooth, elongated and posteriorly narrowed, with rounded point. Y. (Y.) hyperborea (Loven). similar to Yoldia s. s., — Cnesterium Dall, Section 1898. Scissula Dall, which the furrows are confined to the median part of the shell, lines at sharp angles. Shell but with oblique furrows which cut the growth Y. (C.) scissurata synonymized with Cnesterium by Dall. Dall. — 1909, in was later Section Kalayoldia Grant & Gale, 1931. Shell elongated; rostrum concave above; surface concentrically furrowed. Y. (K.) cooperi Gabb. — Section Adrana H. & A. Adams, 1858. Shell greatly elongated, without strong periostracum; anterior sides sometimes scarcely different; umbo side with weak, somewhat oblique furrows. Few and posterior scarcely projecting, Y. Central American species. 4. Family SOLENOMYIDAE Shell elongated, anteriorly and posteriorly rounded, thin, of characteristic prisms, with very strong, smooth, surpassing the calcareous shell weaker less exterior (A.) elongata (Sowerby). at elastic the margin which composed periostracum contains radial striae; the ligament, situated far posteriad, has a sunken cartilage, several more or borne on strengthened ridges of the calcareous shell; a ridge also lies anterior to the muscle; the hinge margin is attachment of the posterior adductor completely toothless. 1210 The animals have an elongated burrowing directed end of which bears a disk which nuculids; bipectinate, gills laterally is foot, the anteriorly serrate at the margin, as in directed; palps with labial short tentacles; mantle margin fused, leaving an anterior opening for the foot and a narrow, posterior opening surrounded by tentacles; statocysts open as in nuculids; intestine with only a weak coil behind the stomach; by the ventricle elongated, traversed intestine; kidneys sack-shaped, with 2 short anterior limbs which contain the pericardial funnel and the renal apertures; the gonads open into the kidneys. Solenomya Lamarck, 1818 (Solemya) Synonym Stephanopus Scacchi, 1833. Characters of the family. A few species burrow in sand in most cases. Ligament extending more or less far in various seas; they Section Solenomya s. s. forward, mainly internal. S. (S.) australis Lamarck. Dall, 1908. Ligament situated posterior borealis Totten. — is It — Section Petrasma umbones, internal. S. (P.) Section Acharax Dall, 1908. Ligament situated posterior umbones, completely to the to the not clear external. S. (A.) how Solemyarina johnsoni Dall. Iredale, 1931 (S. velesiana Iredale), can be separated. II. ARCACEA not nacreous, nearly always equivalve; Shell open; STIRPS gills mantle completely with 2 rows of identical filaments, in most cases with two more or less limb, interconnected only by limbs, sometimes 1. broadened on the side facing the ascending cilia; Family labial palps without appendages. ARCIDAE umbones, between which most cases rhomboidal ligament on a more or less broad dorsal the hinge margin bears several denticles, the outermost of which Shell nearly always ribbed, with elevated lies in field; are often placed obliquely, sometimes parallel to the margin; the periostracum often bears bristles or lamellae. The foot as rule has a 792 simple byssus stem; the heart and pericardium are sometimes double, bilaterally symmetrical, either lies below the sometimes simple, intestine or is pierced are completely separated from each in the latter case the ventricle by it; the sack-shaped kidneys other; the pericardial branch or less short, sometimes ending close to the kidney aperture. is more 1211 Area Linne, 1758 Characters of the family. Numerous species in all seas. Subgenus Navicula Blainville, 1825 (synonyms? Daphne + Daphnoderma Poli, 1795; ? Cyphoxis Rafinesque, 1819; Byssoarca Swainson, 1833; Thyas Gray, 1853; Arcoptera Heilprin, umbones which strong 1857 (non Koch, 1886). Shell long, straight Cibota Morch, boat-shaped, with from one another; a broad dorsal are separated surface; a large rhomboidal ligament with a a 1835); elongated, few oblique reinforcements; hinge margin with numerous small teeth; somewhat gaping ventrally for the passage of the byssus. A. (N.) noae Linne (Fig. was named 793). This species again later by Lamy, as genotype of monograph of 1907, in his Schumacher, 1817, had already designated genus. Fig. A few species in warm 793. Internal side of the left Area by Gray and the genus; however, A. antiquata as the type of the seas. shell valve of Area (Navicula) noae Linne. Length about 7 cm. Subgenus Litharca Gray, 1842. Shell with high umbones situated behind the center, from which a very sharp edge descends to the posterior corner, whereas the anterior part gradually narrows and ends in a rounded point; surface with radial, scaly ribs; dorsal surface deeply grooved, with large ligament which gradually pointed, ventrally; is posteriorly rounded and anteriorly containing a few oblique bands; somewhat gaping hinge margin straight with numerous small denticles. A. (L.) lithodomus Sowerby, on the west coast of Colombia. Subgenus Scaphula Benson, 1834. Shell small, broad and low, boatshaped; umbo situated far forward, with corner, flattened below; surface sharp edge to the posterior weakly sculptured; dorsal surface fairly 1212 broad; ligament rhomboidal, situated between the umbones, leaving the posterior part of the dorsal surface free; hinge margin weak, median denticles small or absent, outer ones oblique. A. (S.) celox Benson. Few species in Indian rivers. Subgenus Barbatia Gray, 1842 (synonym Savignyarca Jousseaume, somewhat angular; 1891). Shell laterally compressed, elongated oval or umbo close to the center; dorsal surface and ligament narrow; surface in most cases with teeth, the are larger and in bristles or small warmer more or less oblique. A. (B.) Subgenus Trisidos (Bolten) Roding, umbo peculiarly twisted; dorsal elevated; barbata Linne. A few species seas. 1815; Parallelepipedum (Klein) Morch, 793 hinge margin with numerous scales; median of which are weaker or reduced, whereas the outer ones surface 1789 (synonyms 1853). anterior to situated the Trisis Oken, strong and large, Shell moderately center, and ligament long and narrow; anterior end rounded; posterior end truncated; surface finely ribbed; ventral side not gaping; hinge margin long and straight; median teeth weak, outer ones The byssus consisting of a few oblique. threads. A. (T.) tortuosa Linne. 2 species in the Indo-Pacific region. Subgenus Acar (Gray) H. (Gray) H. elongated; & A. umbo & A. Adams, 1857 (synonym Calloarca Adams, 1857). situated in front Shell fairly small, in most cases of the center; dorsal surface fairly more or less finely ribbed; ventral side not gaping; median hinge teeth weak or rudimentary, outer ones oblique; byssus weak. Section Acar s. s. Shell narrow; ligament restricted to its posterior part; surface with a posterior edge, medium-sized; ribs often tuberculate. A. (A.) plicata Chemnitz. anteriorly, — Section Bentharca Verrill, 1898. Shell small, lower without posterior edge. A. (/?.) asperula Bathyarca Kobelt, 1891 (synonym Microcucullaea in Dall. Iredale, most cases small, scarcely ribbed, without edge, more or ventrally rounded. A. (B.) pectunculoides Scacchi. A — Section 1929). Shell less high, few deep-sea species. Subgenus Arcopsis Koenen, 1885 (synonym Fossularca Cossmann, 1 887). Shell fairly small, short; surface in close to the center; the umbones and free; are it more or less most cases finely ribbed; umbo short ligament lies between the leaves the anterior and posterior part of the dorsal surface has densely placed transverse thickenings; the median hinge teeth small, the outer ones oblique. A. (A.) quadrilatera Lamarck |. Cossmann, 1912, proposed a section Galactella for the Recent A. lactea Linne. 1213 & A. Subgenus Noetia (Gray) H. more or or fairly short, with a Adams, 1857. Shell colorless, longish ligament with less distinct posterior edge; several transverse thickenings. Section Paranoetia n. sect. Shell longish, fairly thin, with smooth ribs, umbo without distinct edge; elevated, situated in front of the center; ones oblique. A. (P.) lateralis Reeve. — median hinge only slightly teeth small, outer Section Noetiella Thiele, 1931. Shell rounded trapeze-shaped; umbo situated slightly behind the center; posterior edge weak; surface finely hinge margin fairly short, latticed, with brown periostracum; area narrow; weakly curved; median denticles small, outer ones oblique; ventral margin smooth, not gaping. A. (N.) pectunculiformis Dunker, near Java. ribbed; umbo — Section Noetia s. s. Shell strong, triangular, strongly elevated and posteriorly directed, greatly with distinct posterior edge; hinge margin broad; anterior teeth angular, posterior ones oblique; ventral margin strongly denticulate; periostracum scaly. A. (N.) reversa Gray. Few Subgenus Area species near Central America. s. s. Shell strong, strongly ribbed, with large umbones close to the center and a posterior edge; dorsal surface fairly broad, with strong ligament, which in most cases contains a few oblique bands; hinge margin ventral straight, with numerous teeth which differ only slightly in size; margin strongly denticulate, not gaping. Foot with shallow warm seas. Section Area s. s. (synonyms Anadara Gray, 1847; Anomalocardia (Klein) Morch, 1853, groove, without byssus. Several species in non Schumacher, 1817). The two valves not antiquata Linne. distinctly different. A. (A.) Section Scapharca Gray, 1847. Right valve somewhat smaller than the left. Dall, 1898. Size and sculpture of the two valves Say 794 — (? A. (S.) inaequivalvis Bruguiere. = brasiliana Lamarck). Imparilarca Iredale), is probably not separable. — Iredale, Section Cunearca Subgenus Argina Gray, 1842. Shell roundly area and ligament very narrow; (S.) not gaping. A. 1842. Shell senilis oval, ribbed; Lamarck. umbo situated many hinge margin with umbones and very few anterior to (A.) campechiensis Gmelin = pexata denticles posterior to the folded, incongrua 1929 (hubbardi Section Senilia Gray, very large and strong; periostracum smooth. A. far forward; — differ. A. (C.) species near Central America. Lunarca Gray, 1842, is margin it; Say. Few probably identical. Subgenus Cucullaea Lamarck, 1801. Shell strongly bulging, trapeze- umbo situated and ligament moderately broad; hinge margin straight, shaped, finely and densely ribbed, with a posterior edge; in the center; area anteriorly and posteriorly demarcated by distinct corners; hinge teeth in the center short, anteriorly and posteriorly longer, very oblique, nearly parallel to the margin; anterior scar elevated lamella-like; margin of the posterior adductor muscle ventral shell margin finely denticulate, not gaping. A. (C.) concamerata Martini, in the Indo-Pacific region. 1214 Family 2. GLYCYMERIDAE umbo Shell strong, of variable size, roundish; in the center, thickenings; more or less projecting; in most cases situated ligament external, with oblique hinge margin curved; median teeth sometimes reduced, outer ones oblique; surface ribbed or smooth; adductor muscle scars only slightly differing, toward the center more or distinctly delineated from the posterior gaping ventrally. Mantle and deeply cleft less elevated; the pallial line margin denticulate, not scar; shell similar to those in Area; foot large, gills without byssus; pericardium and heart unpaired, ventrally, by the the ventricle traversed kidneys separated from one intestine; another, situated outside the foot muscles. Glycymeris Da Costa, 1778 Characters of the family. warm seas, at moderate depths. (synonyms Axinaea + Axinaeoderma Several species, mainly in Section Glycymeris s. s. Tuceta (Bolten) Roding, 1795; smooth or finely 1798; Veletuceta Iredale, 1931). radially striated. G. (G.) glycymeris (Linne). Pectunculus^ Lamarck, 1799. Shell with more or less — Poli, Shell Section broad and high G. (P.) pectunculus (Linne). Tucetona flabellata (Tenison- Woods)] ribs. and Grandaxinaea Iredale, different. 1931 — {magnificens Iredale) are scarcely Section Melaxinaea Iredale, 1930. Shell with narrow ribs and concentric threads. G. (M.) labyrintha (Iredale). 3. Shell in Family LIMOPSIDAE most cases small, often with bristly surface, white or more seldom brown colored, usually roundish or oval and somewhat inclined; ligament more or less sunken, short; the hinge margin sometimes bearing teeth, sometimes only few or none at all; inner shell margin smooth or denticulate, the anterior adductor muscle is smaller and situated higher than the posterior one and may disappear completely; the foot is fairly small, often with a posterior tip and has a fairly weak several byssus; gills fairly broad, with separate filaments, occasionally without ascending limb. In the deep sea and colder seas. Addition from Part 3 (1934) 1010. Because the name Pectunculus is preoccupied by should be replaced by Tucetona Iredale. 1 : this Da Costa, 1778, (see p. 1348), 1215 Limopsis Sasso, 1827 795 & Synonyms Trigonocaelia Nyst Galeotti, 1835; Pectunculina & Rochebrune, 1889; Cosmetopsis Rovereto, 1898; Loringella + Phrynelima + Aspalima Iredale, 1929; Versipella + ? Senectidens + ? Glycilima Iredale, 1931. Orbigny, 1844; Mabille Felicia most cases more or Shell small to medium-sized, roundish, in less inclined and colorless, with bristle-bearing periostracum; external surface weak with situated the often cartilage umbo radial or concentric sculpture- in center of the only slightly projecting, hinge margin; ligament with triangular somewhat ingressing hinge margin, which the into is arched or angular; the tooth row interrupted in the center; posterior adductor muscle scar larger than the anterior one; ventral shell margin smooth or L. denticulate. aurita (Brocchi). Several species, mainly in the deep sea and in cold seas. A the few groups may be accepted as thick-shelled L. loringi Aspalima (erecta Hedley & sections, such as Loringella, for Angas with Petterd) is distinct similar; it concentric sculpture; seems doubtful whether Glycilima (paradoxa Iredale) can be accepted. Section Empleconia Dall, 1908. Upper part of the anterior margin deeply indented, forming an exterior excavation. L. (E.) vaginata Dall, in the northern Pacific Ocean. Pleurodon S. Wood, 1840 Synonyms Nuculina Orbigny, 1845; Nucinella S. Wood, 1850; Huxleyia A. Adams, 1860; Cyrilla A. Adams, 1862; Diabolica Jousseaume, 1897; Cyrillista + Cyrillona Iredale, 1929. smooth with concentric furrows; ligamental very small; hinge margin fairly broad and short, with a few, in Shell small, inclined oval, cartilage most cases strong tooth; shell teeth; on the posterior side with an elongated P. ovalis S. Wood Few f- living species (Fig. 794) in various seas. Cratis Hedley, Shell lateral margin smooth. somewhat inclined small, shaped embryonic shell, 1915 oval, with demarcated, low hat- externally with finely net-like sculpture; ligamental cartilage situated in the center; hinge margin strong, with few (5) distinct teeth; anterior margin with a few wart-shaped teeth on the lower part of and on the posterior margin. 1216 Fig. 794. Internal and external sides of a shell valve of Pleurodon pretiosus (Gould), enlarged. C. — a, hinge margin, more strongly enlarged. progressa Hedley, near east Australia. Denticosa Iredale, 1930, proposed for "Philobrya" cuboides Verco, seems to be scarcely different. Lissarca Edg. Smith, 1879 Synonym Austrosarepta Hedley, Shell small, inclined 1899. or rounded oval rhomboid, externally umbones concentrically striated, with small ligamental cartilage below the 796 and weak hinge margin, which bears few small anterior and posterior denticles; with a few small tubercles on the posterior margin and in most cases also on the anterior margin. L. rubrofusca Edg. Smith. About a dozen species in southern seas. Limopsilla Thiele, 1923 Shell small, thick-walled, roundly triangular, with demarcated embryonic shell, below it with a very small ligamental cartilage; hinge margin transversely grooved, with a few denticles in front of and behind the center; ventral L. margin smooth. pumilio (Edg. Smith), near South Africa. Lissarcula Thiele, 1923 Shell exteriorly with concentric and radial threads; embryonic shell hat- shaped, situated in front of the center; anterior margin arched, posterior margin only slightly arched; hinge margin transversely grooved, anteriorly and posteriorly with 2 denticles; ventral margin with a few small tubercles. L. australis Thiele, near Australia. 1217 Hochstetterina nom. nov. Synonym Hochstetteria Velain, 1877, part. more or roundish, inclined; embryonic shell Shell the close to center of the hinge demarcated, less which has only transverse margin, grooves but no teeth; ligament below the umbones, sometimes asymmetrical; more or surface margin denticulate shell less concentrically striated; distinctly to a greater or lesser extent. H. crenella (Velain). Few species in southern seas. Because Kobelt, 1884, designated Hochstetteria aviculoides Velain as the typical which Bernard has included species, in Philobrya, the name must be changed. generic Adacnarca Pelseneer, 1903 somewhat roundish, Shell embryonic shiny; shell transversely grooved inclined, hinge margin; weakly radially thin, not demarcated, close to shell anterior adductor muscle very small; inner the striated, center of the margin finely denticulate; lamina without ascending gill lamella. A. nitens Pelseneer, in the Antarctic Sea and one Australian species. Philobrya Carpenter, 1872 Shell with nearly or completely anterior, often distinctly demarcated, embryonic more or shell, from the center of which the ligament extends obliquely less far backward, separating a short anterior part from a longer posterior part of the in most cases transversely grooved hinge margin; the shell is rows of sometimes bristles distinctly, or unribbed; present, especially sometimes only indistinctly, ribbed with sometimes ridge-like marginal teeth are below the posterior end of hinge margin; an anterior adductor muscle absent. Several species, mainly in southern seas. Section Hochstetteria Velain, ligament short. P. 1877. Anterior shell margin convex; aviculoides (Velain). — Section Philobrya s. s. (synonyms) Byrophila Carpenter, 1864 (non Treitschke, 1825); Briophila P. Fischer, (/-/.) 1886; Philippiella Pfeffer, 1886; Stempelleria Clasing, 1918; Stempellia N. Odhner, 1922). Anterior margin straight or concave; shell not distinctly ribbed, often with radial rows of bristles; ligament distinctly 797 elongated. P. (P.) setosa (Carpenter). The Antarctic species, for Hedley recognized the group Philippiella, are so similar mentioned Californian species, that they can which to the above scarcely be separated. 1218 — Section Cosa costata Bernard. 1927. Finlay, — with distinct radial Shell ribs. P. (C.) Section Notomytilus Hedley, 1916. Shell brown, with nearly or completely terminal, not demarcated umbones; posterior margin with a few small tubercles. P. (N.) rubra (Hedley). Micromytilus Cotton, Section 1931 [P. crenatulifera (Tate)] (Fig. 795) is scarcely different. — Verticipronus 1904. Hedley, flattened, with radial shell Shell similar to Notomytilus; embryonic sculpture, brown; anterior part of the hinge margin elevated tooth-like, below the posterior end of which there is a Section Neocardia Sowerby, bifurcated ridge. P. (V.) mytilus (Hedley). — 1892. Shell with concentric and radial sculpture or smooth, colorless, with a double ridge below the posterior part of the hinge margin. P. (N.) A angulata (Sowerby). Fig. 795. Interior side couple of South African species. of a shell valve of Philobrya (Micromytilus) crenatulifera (Tate), enlarged. Order 2. ANISOMYARIA Anterior adductor muscle reduced or completely teeth lost. True hinge scarcely present, but sometimes small tubercles or special tooth formations are developed; embryonic shell with grooved hinge margin. Mantle open, without siphons; gill lamellae smooth with identical filaments or folded with nonidentical filaments. I. Shell in STIRPS MYTILACEA most cases with umbones near the anterior end of terminal; equivalve, often elongated or anteriorly narrowed to pointed, sometimes oval; interior side in most cases nacre-like shiny, occasionally external or internal not very conspicuous prismatic layers are developed; ligament nearly always external, situated posterior to the umbones; hinge margin toothless, but sometimes with a few small tubercles in front of or behind the ligament, primitively corresponding to the ends of external ribs. The mantle forms radial a closed, sometimes elongated excurrent siphon; 1219 is as a rule developed in the posterior part of the mantle; the of separate filaments, similar to those in arcids; the anterior consist gills is sometimes well developed, but in most cases small, muscle adductor a retractor seldom completely most cases foot finger-shaped, with a byssus in lost; consisting of several threads; statocysts open, with small sand grains; the kidneys lie outside the foot retractors beside the pericardium, they are sack-shaped with posterior opening; in a few groups the gonads extend into the mantle. 1. Characters of the MYTILIDAE Family stirps. live in the sea, with the exception The animals of a few which have invaded freshwater. Idasola Iredale, 1915 798 Synonym Shell longish; 1876, non Mulsant Idas Jeffreys, small, umbo anteriorly rounded, close to the anterior end; grooved; ligament external; surface finely Fig. 796. Idasola /. & Verreaux, 1876. posteriorly obliquely truncated, hinge margin transversely latticed; inner margin smooth. argentea (Jeffreys). argentea (Jeffreys) (Fig. 796), in the Bay of Biscay (deep Dacrydium Shell small, colorless, 1859 Torell, smooth, thin, sea). obliquely oval; umbo small, close to the anterior end; hinge margin transversely grooved; ligament obliquely ingressing below the umbones; anterior adductor muscle attached close to the margin. The gonad the deep sea. lies Few species They make nests with D. vitreum Holboll. in the in body. most cases their byssus. in cold seas and in — 1220 Crenella T. Brown, 1827 Synonyms Stalagmium Conrad, 1833; Hippagus + Myoparo Lea, 1833; Nuculocardia Orbigny, 1845; ? Crenellodon Edwards, most cases with Shell small, oval or rhomboidal, in and with small tubercles inner margin; ligament short. Excurrent at the siphon not elongated; foot thickened end, with a byssus thread. at the Few species in various seas. Subgenus Rhomboidella Monterosato, 1884. rhomboidal, similar to Dacrydium, but differing tuberculate margin. C. (/?.) Subgenus Crenella tuberculate margin. Subgenus Solamen related is placed the to latter obliquely Shell sculpture and the rhombea (Berkeley). Shell s. with distinct sculpture and oval, 1924. Shell oval, with Iredale, (S.) rex Iredale. Arcoperna It weak near Botula as a section of Modiolus. is sculpture seems doubtful whether this Conrad) from the Eocene; Dall (filosa 1929, for Scapha Verco, Iredale, in C. (C.) decussata (Montagu). and smooth margin. C. group s. 1891. radial sculpture Exosiperna smaller and stronger. Modiolus Lamarck, 1799 Synonym Modiola Lamarck, 1801. Shell with blunt umbones which anterior end but not terminal; surface long, external; distinct, fairly are more or smooth or less bristly; close to the ligament fairly hinge margin toothless. The anterior adductor muscle close to the anterior margin; the gonads not or only slightly extending into the mantle. Several species in various seas. Subgenus Adipicola Dautzenberg, 1927 (synonym Myrina H. Adams, 1857, non Fabricius, 1808). Shell long, & A. anteriorly distinctly elongated and rounded, somewhat lower than the posterior part; surface smooth; ligament sunken. M. (A.) pelagicus (Forbes). Subgenus Modiolus s. s. Umbo close to the anterior end, which forms a short, rounded corner; posterior end significantly elevated, from the umbo. Section Modiolus (synonym Eumodiolus Jhering, 1900). Shell hairy or not hairy. M. (A/.) modiolus (Linne). Limnoperna Rochebrune, 1882, proposed inflated in the line extending posteriorly s. 799 s. for small freshwaters of east Asia, is scarcely different. M. (L.) siamensis For the small Australian "ModiolaricT subtorta Dunker, 1924, proposed a genus Fluviolanatus, the systematic position of (Morelet). Iredale, which is sculpture; uncertain; umbo the shell is fairly long and low, without distinct close to the anterior end. 1221 Subgenus Amygdalum Megerle von Mixhlfeld, 1811. Shell thin and smooth, pale, often with colored pattern; the animals build nests with their Section byssus. 1898 (synonym Nudiola Modiolula Sacco, Monterosato, 1917). Shell moderately long, inflated, in most cases hairy. M. (M.) phaseolinus (Philippi).—Section Amygdalum Monterosato, Modiella elongated, Shell 1884). not s. s. (synonym M. (A.) inflated. arborescens (Chemnitz). was proposed by Scopoli, 1777, Volsella for bivalves with denticulate hinge margin, and his inclusion of Mytilus modiolus Linne indicates that he misidentified this species, which has toothless hinge margin; because the other included species are likewise not recognizable, included this may be genus name rejected because of insufficient substantiation. Brachyodontes Swainson, 1840 (Brachidontes) Shell in most cases with radial sculpture, anteriorly somewhat rounded or pointed; umbo nearly or completely terminal; ligament short; the dorsal line the hinge margin; a fairly sometimes forming a rounded corner posterior to few small tubercles are developed anterior and posterior to the ligament. Several species in various seas. Subgenus Brachyodontes umbo nearly terminal; s. surface Shell s. muscle present. Section Brachyodontes curved. B. (B.) sulcatus (Lamarck). in South and East Asia. — anteriorly radially ribbed; Section A s. s. rounded or blunt; an anterior adductor Ventral margin anteriorly few small species live in freshwater Hormomya Morch, 1853 (synonyms Stavelia Gray, 1858; Trichomya Jhering, 1900). Ventral margin elongated. B. (//.) exustus (Linne). Subgenus Ischadium Jukes-Browne, 1905. ventral Umbo terminal, pointed; margin somewhat concave; surface radially ribbed; an anterior adductor muscle absent; posterior foot retractor broadly fused with the adductor muscle. B. (I.) hamatus (Say). Subgenus Septifer Recluz, 1848. Shell with pointed terminal umbo and a plate on either side in the interior of the anterior corner, at which the anterior adductor muscle attaches; the posterior adductor muscle posteriorly surrounds the attachment of the posterior foot retractors; the gonad branches in the mantle. B. (S.) bilocularis (Linne) (Fig. Subgenus Mytilaster Monterosato, 1883. Umbo 797). nearly terminal; surface with only growth lines or zig-zag-shaped wrinkles, with a few small tubercles posterior to the ligament and few anterior ones. B. (M.) lineatus (Gmelin). 1222 Interior side Fig. 797. of the right shell valve of Brachyodontes (Septifer) biloculahs (Linne). mm. Length about 46 Musculus (Bolten) Roding, 1798 Synonyms Modiolaria Beck, 1838; Lanistes Swainson, 1840; 800 Modiolarca Gray, 1843; Lanistina Gray, 1847. Shell more or less long, in most cases transversely oval; umbo close to the anterior end; outer side anteriorly and posteriorly radially ribbed, smooth in-between; inner margins with small tubercles; ligament moderately long; attachment of the anterior adductor muscle close to the ventral margin. The excurrent siphon is more or a rule, closed tube-shaped; the lower one is and as less elongated, ventrally open; the gonads penetrating the mantle. Several species in most seas; they are absent in the Antarctic. Subgenus Gregariella Monterosato, 1884. Shell elongated, cases hairy on the posterior part. Section Gregariella s. s. lower than posteriorly. M. (G.) petagnae (Scacchi). distinctly in most Shell anteriorly — Section Botulina Dall, 1889 (synonym Trichomusculus Iredale, 1924). Anteriorly not lower than posteriorly; posterior edge in most cases beset with bristles. M. (B.) opifex (Say). Subgenus Musculus s. s. Shell transversely oval, not hairy. M. (M.) discors (Linne). Lithophaga (Bolten) Roding, 1798 Synonyms Lithophagus Megerle von Muhlfeld, 1811; Lithodomus Cuvier, 1817. Shell more or anterior end less elongated, cylindrical; or terminal; umbo close to the rounded surface smooth or wrinkled; hinge margin smooth; ligament more or less long, sunken; scar of the anterior adductor muscle close to the ventral margin. Mantle with shorter elongated, or longer siphons; an acid-secreting gland lies in which the animals bore A few species into limestone. in various seas. its anterior part, by 1223 Subgenus Lioberus 1898. Dall, Shell inflated, smooth, moderately elongated, fairly thin, anteriorly very shortly rounded, somewhat lower than posteriorly; beak anteriorly inclined; mantle with long incurrent and siphons. excurrent castanea (Say). Leiosolenus Carpenter, (L.) L. may Carpenter) 1856 (spatiosus represent a related group. Subgenus Botula Morch, 1853. Shell similar to Lioberus, but with anteriorly located beaks. L. (B.) fusca (Gmelin). Subgenus Adula H. or transversely grooved; & A. Adams, 1857. Shell long and low, smooth umbo not situated close to the anterior end, with a posteriorly extending edge. L. (A.) soleniformis (Orbigny). Zelithophaga 1927 [truncata (Gray)] Finlay, Fig. scarcely different. is 798. Shell of Lithophaga lithophaga (Linne). Length about 8 cm. Subgenus Lithophaga s. Shell long, cylindrical; s. anterior end. Section Lithophaga (L.) s. s. lithophaga (Linne) (Fig. 798). umbo close to the Without calcareous deposition. — Section Myoforceps P. L. Fischer, 1886. With a smooth calcareous deposit posteriorly ending in a projecting point. L. different. (M.) caudigera —Section (Lamarck). Labis Diberus Dall, 1898. Dall, 1916, is scarcely Calcareous deposition with peculiar feather-shaped sculpture. L. (D.) plumula (Hanley). Mytilus Linne 1758 801 Shell anteriorly pointed, with nearly or completely terminal most cases with few small muscles small, sometimes absent. anteriorly in denticles; umbones, anterior adductor Several species in various seas. Subgenus Mytilus s. s. smooth, anteriorly below the (synonym Eumytilus Jhering, 1900). umbo Shell with a small ribbed expansion, the margin of which bears 2-5 small denticles; anterior adductor muscle present. M. (A/.) edulis Linne. 1224 Subgenus Chloromya Morch, 1853. Shell smooth; umbo terminal, in the interior of the anterior end with an inflection of the margin, which forms a small plate similar to muscle. Section Chloromya s. s. end; marine. M. (C.) perna Linne. umbo small; very pointed, septum; without anterior adductor a With — 1 or 2 hinge teeth Section Sinomytilus interiorly toothless; ventral delimited by a sharp edge. M. (S.) crosseanus (Morlet). in freshwater A at the anterior Shell thin, fairly n. side concave, couple of species from China and Indochina, which have been described as Dreissena. Subgenus Aulacomya Morch, 1853. Shell umbo side radially ribbed; large, terminal, projecting over the inner margin; with a ridge muscle in most cases absent. M. II. (A.) magellanicus Chemnitz. STIRPS PTERIACEA Shell laterally compressed, variably formed; ostracum of prisms, in on one anterior adductor corresponding to a furrow of the other valve; most cases thin at formed completely hypostracum weak and the margin; considerably smaller than the ostracum, nacreous; hinge margin straight, toothless; mantle open, joined with the gills by ciliary junctions; anterior adductor muscle small or reduced; foot in most cases with byssus; the mantle cavity posteriorly extending far upward. 1. Family VULSELLIDAE Ligament sometimes with several gill cartilages, sometimes with only one; lamellae as a rule smooth, filaments identical. Crenatula Lamarck, 1804 Hinge margin to the fairly long; ligament with several small cartilages posterior somewhat elevated umbones; anterior margin curved, posterior margin obliquely truncated; mantle margin with papillae; foot without byssus. C. viridis Lamarck. Few species in the Indian Ocean and Red Sea, in sponges. Pedalion (Solander) Huddesford, 1770 Synonyms Isognomon (Klein) Solander, 1786; Melina Retzius, 1788; Perna Bruguiere, 1792; Vulsella Mus. Calonn., 1797 Isogonum (Bolten) Roding, 1798; Sutura Megerle von Muhlfeld, 1811; Isognomum (Klein) Morch, 1853. 1225 umbo Shell nearly equivalve, externally often scaly; end of the sometimes short, the anterior at sometimes posteriorly elongated hinge ligament with several strong cartilages situated in pits; retracted and somewhat gaping. Foot tongue-shaped, with byssus; lamellae smooth. A few species warm in Section Pedalion — s. lsognomum Morch, 1853. with elongated hinge margin. P. (/.) isognomum ephippium (Linne). short, gill seas. Hinge margin not strikingly elongated. P. s. line; anterior margin Section (P.) and Shell high (Linne). Foramelina Hedley, 1914 Shell strong; hinge margin fairly short, with several cartilages; right valve with a hole below the umbo, from which a suture extends to the emerges through the hole, anterior end of the hinge margin; the byssus it consists of a bundle of threads; the byssus muscle adductor muscle and attaches to the F. left is stronger than the valve above the latter. exempla Hedley, near Australia. 1798 Vulsella (Bolten) Roding, Synonym Reniella Shell and tall Swainson, 1840. margin short, often gaping; hinge short, with a strong end cartilage in an oblique, triangular pit, inclined posteriorly; posterior often heart A somewhat concave. Foot without byssus and without retractors; chambers paired; gill lamellae smooth or somewhat pleated. few species living Section Vulsella sized; gills folded s. s. in V. (?). sponges, in the Indo-Australian region. (synonym Abisa Gregorio, 1884). Shell medium(V.) lingulata Gregorio, 1884. Shell fairly small; gills Lamarck. smooth (?). — Section Madrela V. (M.) spongiarum Lamarck. Malleus Lamarck, 1799 Synonyms Pinctada (Bolten) Roding, 1798 Himantopoda Schumacher, 1817. Shell tall and short, part.; Tudes Oken, 1815; often with folded margins and more or less elongated hinge margin; ligament similar to that in Vulsella with a strong cartilage in an oblique, triangular pit; umbo only slightly projecting. The foot consisting of 2 parts, the larger anterior one is long finger-shaped, with ventral glandular groove, the smaller posterior one tongue-shaped with byssus and groove; the posterior byssus muscle attaches to the shell below the adductor muscle; gill lamellae smooth; heart asymmetrical. 226 A few species in warm seas. Section Parimalleus Iredale, 1931. Shell fairly small, with wrinkled nucleus, Iredale. without prolongation of the hinge margin. M. (P.) cursator — Section Malvufundus Gregorio, 1885. Hinge margin without — anterior prolongation. M. (M.) anatinus Lamarck. Gregorio, 1884 (non Zeller, ? Section Fundella 1848). Without anterior prolongation of the hinge margin internally with a median constriction. M. {F.) lioyi Gregorio. — Section Malleus M. (M.) s. s. Hinge margin prolonged anteriorly and Lamarck vulgaris Fig. (Fig. posteriorly. 799). 799. Shell of Malleus vulgaris Lamarck. Length about 18.5 cm. 2. 803 Hinge margin Family PTERIIDAE straight, posteriorly angularly demarcated or elongated; ligament somewhat sunken, fairly long, posterior to the only slightly projecting, anteriorly inclined umbones; hinge margin with 1 or 2 inconspicuous tooth-like thickenings below the umbones; anterior corner demarcated ear-like by the byssus notch; surface often scaly; left valve somewhat more bulging than the right. The single adductor muscle attaches in the center; the anterior foot retractors attaching below the umbones; gill lamellae folded, with large inner border filaments, they are 1227 attached to the mantle by ciliary tufts; triangular, short, foot with byssus; kidneys sack-shaped, situated below the pericardium; ciliated funnel connected with one another in the upper and posterior corners. Pteria Scopoli, 1777 Synonyms Avicula (Klein) Bruguiere, 1792; Glaucoderma + Glaucus 1795 (non Forster, 1777, nee Gmelin, 1791); Anonica Oken, 1815. Poli, Characters of the family. warmer Several species in the seas. Section Electroma Stoliczka, 1871. Shell fairly small and thin; hinge margin posteriorly retractors below it obliquely truncated; foot smaragdina (Reeve). Section Pteria slightly elongated, symmetrical. P. (£.) — Hinge margin posteriorly greatly prolonged; foot retractors asymmetrical. P. (P.) hirundo (Linne) (Fig. 800). Separation of s. s. Austropteria — Iredale, 1931 {saltata Iredale), Section Pinctada (Bolten) Roding, from Pteria is not clear. 1798 (synonyms Unionium Link, 1807; Margaritiphora Megerle von Muhlfeld, 1811; Meleagrina Lamarck, 1812; Margarita Leach, 1814; Perlamater Schumacher, 1817). Shell only slightly inclined, nearly equivalve; posterior corner slightly elongated. P. (P.) margaritifera Fig. (Linne). 800. Shell of Pteria hirundo (Linne) (after Dunker). 3. Family PINNIDAE Shell large and fairly thin, anteriorly pointed with terminal umbones, posteriorly gradually long, situated in becoming higher, posteriorly gaping; ligament a groove; muscle small, posterior one hinge margin toothless. Anterior adductor close to center of the shell; mantle margin fringed; oral lobes elongated, a peculiar gland of dubious large, 1228 function is present over the upper byssus strongly developed; lip; lamellae folded, with large inner and outer border filaments; worm-shaped process located over the anal gill a long papilla at the posterior end; proximal limb of the kidney fairly long, outer sacks somewhat elongated, with abundant folds, completely separated from one another. Pinna Linne, 1758 Synonym Chimaera Poli, 1791, non Linne, 1758. Characters of the family. Shell often with groove-shaped scales. A 804 few species in the warmer seas. Subgenus Atrina Gray, 1842. Shell without median edge; hypostracum undivided. Section Atrina s. s. Shell regular, in most cases not very long. P. (A.) nigra Chemnitz. — Section Streptopinna Martens, 1880. Shell more or less irregularly formed; ventral margin lobed. P. (S.) saccata Linne. Subgenus Pinna s. Shell with a s. edge corresponding to a deep cleft Linne. Pennaria (Browne) Morch, 1 median longitudinal bulge or an of the hypostracum. P. (P.) rudis 853 {muricata Linne), and Cyrtopinna Morch, 1853 {incurvata Chemnitz), are slightly different; the latter is very elongated, posteriorly obliquely truncated. These clams protrude into the substratum with the pointed anterior end, the gaping posterior end upwardly directed, change so that they cannot their location. STIRPS PECTINACEA III. Shell often inequivalve and with radial ribs; hinge margin moderately long, without true hinge teeth; ligament with a median cartilage in a pit. Mantle lobes separate, sometimes with eyes, often with thread-shaped appendages; gills and foot variously developed; an anterior adductor muscle in most cases absent. 1. Family DIMYIDAE Shell small, with silvery shine, inequivalve, valve; left valve sculpture; somewhat smaller and flatter; cemented with the surface with weak right radial hinge margin straight, fairly short, with weak external and small internal ligament; outline somewhat inclined oval; umbo scarcely projecting; pallial line arch-shaped; anterior adductor muscle fairly small, close to the anterior margin; posterior one larger, distinctly bipartite; gills mantle completely open; margin with papillae, without eyes; with identical filaments without ascending limbs; foot and labial palps rudimentary; sexes separate. 1229 Dimya Rouault, 1848 Synonym Margariona (Dall) 1882. Kobelt, Characters of the family. D. deshayesiana Rouault Indies, D. t; living D. argentea Dall, in the West corrugata Hedley, near South and East Australia, and D. Kawamoto, near Japan. fossil group Dimyodon Munier-Chalmas, 1886, has a hinge radiata The similar to that in Plicatula. Family 2. PECTINIDAE Shell of variable form and size, in radial ribs or folds; most cases inequivalve, often with hinge margin occasionally with diverging lamellae or strong, identical teeth anteriorly and posteriorly; an anterior adductor muscle absent; mantle margin and with in most cases with a broad often without byssus, sometimes rudimentary; pleated; the cerebral ganglia are displaced may even be The internal fold frequently also with eyes; lip margins folded; foot tentacles, gill more or lamellae smooth or less far backward, and fused with the visceral ganglia. habits are variable; a others are able to few groups are cemented by one valve, swim by opening and closing the shell. A. Subfamily Plicatulinae 805 somewhat Shell cemented by the irregularly formed, in valve; right corners, with 2 strong, articulating teeth valve lie radial folds, on either side, which in the right next to ligamental cartilage and are clasped by teeth of the valve; pallial line not far muscle most cases with hinge margin short, without projecting in posterior half. from shell margin; left attachment of the adductor Mantle margin with short tentacles and a narrow interior fold, without eyes; foot rudimentary; gill lamellae with identical two-limbed filaments which are connected by ciliary tufts only at the lower corners and the ends of the ascending limbs; the inner ascending limb sometimes absent; visceral ganglia of simple structure; cerebral ganglia at the base of the labial palps; kidneys with long pericardial ducts, connected with one another; sexes separate. Plicatula Lamarck, 1801 Characters of the subfamily. Synonyms Harpax Parkinson, 1811; Ostrenomia Conrad, 1873. A few species in warmer seas. P. plicata (Linne). 1230 B. Subfamily Amussiinae most cases small and thin, often transparent, more seldom smooth or with weak sculpture, without distinct radial folds, sometimes with internal radial ridges; hinge margin short or moderately Shell in colored, long, sometimes transversely grooved, with the median ligamental main part of shell, in the right vajve often with a deep incision below Mantle margin with few eyes or without such; it. cartilage, ends with projecting corners, which are distinctly delimited from at the gill identical filaments, similar to those in Plicatula; the lamellae with major part of the adductor muscle with transversely striated fibers extending obliquely and crossing the part with smooth fibers; the foot either has a distinct groove and a small anterior pit similar to that in mytilids or the groove is rudimentary and the anterior part of the foot has a large funnel-shaped invagination, the edges of which probably serve for burrowing, similar to that in nuculids. The species live in most cases in the mud of the deep sea or in cold seas. Propeamussium Gregorio, 1883 Shell thin and small, roundish below; right shell with a deep incision below the anterior ear-shaped foot in most cases seems to part. The animals are poorly known; the have a groove and a small anterior pit; sexes separate (always?). Several species in various seas. Subgenus Palliolum Monterosato, 1884. Shell without ribs. Section Pectinella Verrill, 1897. Shell thin, internal radial bulging, somewhat inequivalve, smooth; anterior ear of the right valve fairly large, smooth- margined, considerably larger than the posterior corner. P. (P.) sigsbeei (Dall). — Section Hyalopecten Verrill, 1897. Shell compressed, very thin, transparent, radial — with concentric wave-shaped folds, sometimes with fine lines; ears small, unequal. P. (//.) undatum (Verrill). Section Cyclopecten Verrill, 1897. Shell thin, inequivalve; right valve flattened, somewhat upwardly curved regular concentric borders; 806 left at the margin, in most cases with valve variously sculptured, net-like or with scales or smooth. P. (C.) pustulosum (Verrill). Chlamydella Iredale, 1929 {Cyclopecten favus Hedley) Similipecten is scarcely different. Winckworth, 1932. Shell small and thin, — Section without distinct sculpture; posterior ears poorly delimited; only the right valve has a thin prismatic outer layer. P. (S.) simile (Laskey). — Section Arctinula n. Shell 1231 very thin, colorless, smooth, roundish; right valve somewhat smaller and flatter than the ears of the left valve equal in size, obtusely angled, left; the anterior ones of the right valve rounded at the end; the structure of the valves variable, the right one consists of prisms, which are vertical to the surface, the (A.) one shows left groenlandicum (Sowerby). fine radial lines parallel to the surface. P. — ? Section Cyclochlamys Finlay, 1926. Shell small, rhomboid; ears only slightly delimited; surface with strongly tuberculate ribs. P. ? (C.) transenna (Suter) (position doubtful). — Section Lissopecten Verrill, 1897. Shell shiny, speckled brown and white, exteriorly nearly smooth with very shaped radial (Poli). — weak Section Palliolum equivalve; radial folds, interiorly with many thread- byssus notch ventrally denticulate. P. (L.) hyalinum ribs; posterior ears s. Shell colorless or vividly colored, nearly s. smaller than the anterior ones; surface with microscopic radial sculpture. P. (P.) testae (Philippi). Camptonectes Meek, 1 864 {lens Sowerby t) has been considered by Verrill as closely related to he includes the Recent species Pecten striatus Muller and Palliolum; tigrinus Lamarck with small posterior ears and denticulate byssus notch, the latter with several radial pleats, but these species have pleated gills do not belong Subgenus Propeamussium ridges as in and here. Amussium; s. s. Shell with internal radial accessory right valve flatter, with concentric sculpture; left valve with radial or reticulate sculpture. P. (P.) fenestratum (Forbes). The separation of Ctenamusium not Amussium (Klein, Bolten) Roding, Synonym Pleuronectia Swainson, Shell thin, 1929 Iredale, thetidis (Hedley)], is [P. understandable. smooth or anteriorly 1798 (Amusium) 1840. somewhat inequivalve, indistinctly sculptured, often and posteriorly somewhat gaping; hinge margin ears only slightly different, without byssus notch; roundish, ridges. internally short; the remaining shell with more or less numerous radial reinforcement Mantle margin without eyes; gill lamellae with identical filaments having two limbs; foot with anterior funnel-shaped expansion, without retractors; A gonad hermaphroditic. few species A. pleuronectes in most cases living (Linne) (Fig. 801). in mud in the Paramusium based mainly on the erroneous description of the Smith, but may gills deep sea. Verrill, of A. 1897, is dalli Edg. perhaps be used as a subgroup for the very thin-shelled deep-sea species. 1232 801. Internal side of the shell of Fig. A mussium pleuronectes (Linne). Length about 8 cm. Adamussium 807 n. gen. Shell very thin, roundish, with flat radial folds, exteriorly with densely- placed concentric borders and microscopic radial lines, brownish, ?nteriorly and posteriorly gaping; hinge margin short; ears of the left valve obtusely angled; anterior ear of the right valve rounded and shallowly indented. Animal unknown. A. colbecki (Edg. Smith) in the Antarctic Ocean. This species has such great similarity to Amussium, mainly in the form of the it ears, that probably belongs here, although the radial ridges are absent. C. Subfamily Pectininae Shell in more or less most cases large, the fairly thin, often with distinct radial folds; ears anterior one of the right valve in most cases delimited by a strong incision; the two valves often differently bulging; interior side porcelaneous. Mantle margins with numerous eyes and and with a broad inner tentacles, fold; gill lamellae pleated; foot with byssus, pedal groove and anterior glandular pit, or with an anterior funnel-shaped expansion and more or less rudimentary byssal gland; the unilaterally developed left retractor is weak or completely lost; lips sometimes strong, sometimes very with interlocking processes; visceral ganglia highly developed as the main center for innervation of the sense organs of the mantle margin, often asymmetrical; sexes in most cases separate, more seldom hermaphroditic. species are able to swim by clapping the Many shell. 1233 Pecten (Klein) Osbeck, 1765 most cases with Shell roundish, in demarcated; notch byssal distinct radial folds; ear distinctly sometimes only valves variable; slightly, sometimes very differently bulging. warmer Several species mainly in seas. Subgenus Chlamys (Bolten) Roding, 1798. Shell valves only slightly differing, in most cases fairly flatly bulging, and with radial folds, often rough; anterior ears often distinctly larger than the posterior ones; lower margin of the byssal notch of the right Veprichlamys Iredale, 1929. Shell very (Iredale). perillustris —Section valve denticulate. thin, 1864 (synonym Camptonectes Meek, Eburneopecten Conrad, 1865). Shell and fairly small thin; smooth or with weak similarly bulging and sculptured, Section ? smooth, inclined. P. ? (V.) both valves sculpture radial (C) lens Sowerby f- As stated earlier, a few living species are included here. Belchlamys Iredale, 1929 (aktinos Petterd) is characterized by the and as a rule with fine oblique lines; posterior ears small. P. peculiarly infolded posterior ear; Talochlamys Iredale, 1929 (famigerator Iredale) appears to be similar to Camptonectes. — Section Pseudamussium (Klein) Morch, 1853. Shell fairly thin, with a few flat radial folds and fine dense, occasionally indistinct striae; right anterior ear ribbed. P. (P.) septemradiatus (Muller). — Mimachlamys 1929). Iredale, distinct radial folds larger than Chlamys s. Section Aequipecten P. Fischer, and rows of small the posterior ones. s. roundish, Shell Shell with P. 1 887 (synonym nearly equivalve, with scales; anterior ears (A.) more or opercularis (Linne). — less Section numerous narrow, scaly or spiny small radial most cases distinctly larger than folds, nearly equivalve; anterior ears in 808 the posterior ones. P. (C.) islandicus Muller (Fig. 802). Scaeochlamys Iredale, 1929 {lividus Lamarck) Plagioctenium Dall, is only slightly different. 1898. Both valves more or less — Section strongly bulging, with a few strong radial folds and fine concentric lines; anterior and posterior ears nearly equal — in size. P. (P.) venthcosus Sowerby. Section Pallium (Martini) Schumacher, 1817 (synonyms Decadopecten (Ruppell) Swainson, 1840; Dentipecten (Ruppell) Gray, Shell 1847). only slightly bulging, with few strong radial folds and fine scaly ears more or less differing; at the hinge ribs; margin with a few tubercles. P. Lamarck. Scarcely differing are Manupecten Monterosato, 1872 = Felipes (Locard) Carus, 1889 [P. pesfelis (Linne)]; Peplum Bucquoy, Dautzenberg & Dollfus, 1889 [clavatus (Poli)]; Flexopecten (P.) plica Sacco, 1897 [flexuosus (Poli)]; Mesopeplum Iredale, 1929 (caroli Iredale); and Notochlamys Cotton, 1930 Sanguineus Finlay). Dall, 1898. Shell with many fine — and a few strong Section Nodipecten radial folds which form a few hollow tubercles; ears unequal. P. (N.) nodosus (Linne). 1234 Fig. 802. Shell of Pecten (Chlamys) islandicus Muller. Height almost 9 cm. Subgenus Placopecten Verrill, 1897. Shell roundish, nearly large, equivalve, flatly bulging, without radial folds, with only dense, fine ribs; ears anterior ear of the right nearly equal in size; smooth indentation. P. America. (P.) clintonius Subgenus Equichlamys Iredale, valve with weak, Say, on the east coast of North 1929. Shell fairly large, roundish; both valves moderately bulging, with a few radial folds flattening out toward the margin and with fine anterior one weakly indented. P. ribs; ears (E.) bifrons nearly equal in size, the Lamarck, near Australia. Subgenus Patinopecten Dall, 1898. Shell very large; right valve somewhat more bulging than the left, with several radial folds, which are broader on the right; ears nearly equal in size, on the right with a weak anterior indentation. P. (P.) caurinus Gould. Subgenus Pecten (Klein) Morch, s. 1853). (synonyms Janira Schumacher, 1817; s. Shell inequivalve; ears nearly equal in Vola size, without deep byssal notch; left valve bulging, the right one flat or somewhat concave. Section Pecten s. s. Both valves with distinct radial folds, which are in most cases finely ribbed and rough. P. (P.) adscensionis Osbeck. Notovola Finlay, different. with — 1927 (P. novaezelandiae Reeve) is scarcely Section Euvola Dall, 1897. Left shell greatly bulging, smooth or flat folds, not rough; right valve flat or concave, with or without ribs. P. (E.) ziczac (Linne). Subgenus Hinnites Defrance, 1821. Shell initially similar to that in Chlamys; both valves only slightly bulging, with several rough small radial folds; right valve with a ventrally denticulate byssal notch; later 1235 the animals cement to the substratum with the right valve and 809 more or formed Few less become inequivalve, sometimes thick and heavy, with irregularly ears; the byssus is no longer produced. P. (//.) cortessi (Defrance) f. living species. Semipecten Shell small, & Adams translucent, Reeve, 1848 (Hemipecten) smooth, inequivalve, irregularly roundish, without distinctly delineated ears, but with a deep byssal notch of the right valve, bulging; which is ventrally denticulate as in left flat valve ligamental cartilage small. Mantle margins with tentacles and eyes; foot with byssus and small anterior pit; byssal on the Chlamys; left; gill muscle present only lamellae folded, the ascending arms becoming gradually smaller posteriorly and finally end; sexes separate. S. Fig. forbesianus Adams & Reeve (Fig. 803), in the Indo-Australian sea. 803. Shell of Semipecten forbesianus Pedum Shell greatly compressed, Adams Reeve, weakly enlarged. Bruguiere, 1792 fairly thin, high triangular, with radial sculpture; ligamental surface large, with which & weak deeply ingressing cartilage borne by a fold; left valve flat, anteriorly and by the margins of the right valve, which has a deep byssal notch delineated above by a sharp margin to the umbo. Mantle margins with tentacles and eyes; foot with byssus. is internally posteriorly enclosed P. spondyloideum (Gmelin), in the Indo-Pacific area, in coral reefs. D. Subfamily Spondylinae Shell inequivalve, cemented to substratum by the deeper right valve, as a rule with strong folds or thorns; ligamental surface of the right valve 1236 larger than that of the left valve, with either side with 2 articulating teeth median cartilage; and corresponding hinge margin on pits; the teeth of the right valve situated beside the cartilage, those of the left valve Animal similar lateral. to that in Pecten; more mantle margins with eyes; gill lamellae folded, with large interior border filaments; foot with anterior funnel-shaped expansion, without byssus and without retractors; the may touch them. cerebral ganglia approach the viscerals and Spondylus Linne, 1758 Characters of the subfamily. S. gaederopus Linne. Several species Family 3. Shell seas. LIMIDAE higher than long, in most cases oval, straight or colorless, more or inclined, warm in less bulging, closed or gaping, exteriorly with coarser or finer radial ribs or folds, sometimes with tubercles or scales; situated umbo above the center of the triangular ligamental surface of shifted forward; correspondingly the pit of the cartilage straight or inclined; is hinge margin smooth or denticulate, sometimes there are weak tubercles or ridges in the upper corners. Animal often reddish colored; mantle margins more or less long glandular threads and with nearly always with numerous, 810 a broad interior fold; open pitted eyes are present in only few species; lamellae folded, with strong interior border filaments; the foot has directed backward; it has a byssal groove, whereas a byssus sometimes present, sometimes absent; the along their margins to form a tube which margined is muscle commissure is gill point may be Mantellum are fused open on both in other groups; the large adductor to the posterior margin; the visceral in lips its in lies sides, smooth- high and close most cases greatly shortened and the cerebral ganglia approach or adjoin the visceral ganglia; the interconnected kidneys lie anterior to the adductor muscle; the pericardial limbs, before opening into the distal limbs, receive the exit ducts of the gonads; the ventricle is often cleft. Like some Pectinidae, species of limids are able to swim by rapid opening and closing of the shell; some build nests. Lima Chemnitz, 1784 Synonyms Limaria Link, 1807; Glaucion Oken, 1815. Characters of the family. Many species in various seas. 1237 Subgenus Notolimea more or 1924. Shell small, Iredale, less thick- walled, straight or only slightly inclined, not gaping, bulging, in most cases with strong, frequently tuberculate or scaly radial folds; ligamental more or cartilage small; hinge ridge its broadened and denticulate on less underside; these denticles are sometimes short, sometimes considerably elongated, parallel to one another; only in L. opulenta Thiele are they thickened at the lower ends and therefore arranged fan-shaped in 2 groups interrupted by the cartilage. In unknown. L. subgroups; Gamellima, for crassa Forbes, the mantle Edm 1 Smith. . far this weak austrina (Tate), with L. is 1929, proposed the Iredale, Isolimea, for L. parvula Verco, with thinner shell So cirri opulenta they are present; the anatomy are said to be absent; in L. (N.) australis L. denticles, and and stronger denticles. group has been almost always called Limea Bronn, 1831, however the Homes, show that it has the typical species of which the Tertiary L. strigilata Brochi, various figures of this species, especially one by a few small radial folds in the corners, as in L. murrayi Edg. Smith, but the hinge margin does not have parallel denticles; therefore this group must be called by the name given by Subgenus Limatula S. Wood, Iredale. 1839. Shell in most cases small and fairly thin, distinctly higher than long, strongly bulging, straight or slightly somewhat margin; weak, more seldom strong radial folds; with inclined, projecting, ligamental slightly fused with situated cartilage above the center of the smooth hinge fairly one another; only umbo broad and cirri in Mantle lobes only thin. most cases few in number; foot without byssus and retractors; lips not fused with each other. L. (L.) subauriculata (Montagu). Subgenus Lima s. s. A few species Shell in in all seas. most cases of medium, sometimes considerable, size, fairly thick-walled and only slightly gaping; lips not fused with one another. distinctly anteriorly inclined, fairly flattened or Section Radula thick, (Klein) Morch, 1835. Shell only slightly bulging, scarcely gaping, somewhat concave; ligamental surfaces only slightly diverging; cartilage strong; exterior side with strong scaly radial ribs; L. — animal with byssus and posterior foot retractors; (R.) lima (Linne). Austrolima Section Lima fairly thick, s. s. Iredale, 1929, is gill rachis weak. scarcely different. (synonym Ctenoides (Klein) Morch, 1853). Shell weakly bulging, only slightly inclined; upper part of the anterior margins outwardly curved and gaping; surface with numerous, more or less fine, small radial ribs, somewhat diverging in the center, most cases tuberculate or spiny; in most cases with an oblique ridge This is a typographical error in the original; read Edg. Smith. — Editors. in in 1238 the upper corners of one of the valves; foot with byssus and posterior behind it with a large process; gill rachis moderately strong. Section Acesta H. scabra (Bom) = aspera Chemnitz (Fig. 804). retractors, L. (L.) & — A. Adams, 1858. Shell of thin, somewhat medium inclined; upper part to very considerable size and fairly of the anterior margin infolded; anterior umbo corner only slightly or not projecting; displaced far forward, correspondingly the cartilage pit very oblique; surface with low ribs which are sometimes absent in median the part; foot without byssus and posterior retractors; process behind the foot weak; gill rachis broad. L, (A.) excavata (Fabricius). Callolima Bartsch, 1913 (rathbuni Bartsch) different; the ligament is Fig. more is scarcely superficial. 804. Shell of Lima scabra (Born). Height 8 cm. Subgenus Limea Bronn, 1831 (synonyms Limoarca Minister, 1832; Escalima Iredale, 1929). Shell obliquely oval, thin, not gaping, finely radially ribbed, bulging; ligamental cartilage fairly broad; hinge smooth, in the strigilata (Brocchi) f, the living L. (L.) is margin upper corners with a few small radial folds. L. (L.) murrayi Edg. Smith. This group perhaps closest to Limatulella Sacco, 1898, which is very similar in form and sculpture, differing only by the absence of small folds in the corners. Animal similar to that in Mantellum. L. (L.) loscombi Sowerby. Subgenus Mantellum (Bolten) Roding, 1798. Shell fairly thin, inclined, more or less forwardly produced, in most cases distinctly ventrally gaping, more or less bulging; ligamental surfaces greatly diverging, so 1239 that the shell radial ribs can be widely opened; surface with weaker or stronger which are sometimes somewhat tuberculate; inner folds of the mantle margin very broad, anteriorly in the center broadly fused with one another; foot without byssus and retractors; lip margins fused with one another to form a tube, which open is at both ends; the process behind the foot small. L. (M.) inflata (Chemnitz). IV. Shell inequivalve, during early life ANOMIACEA STIRPS cemented to the substratum indentation of the right valve; this indentation surrounded by the lower margin, so that two valves the structure of the 812 nacre-like, that permanently or only by a calcified byssus, which emerges through a deep of the to that in the pectinid is it is more or less completely often appears as a perforation; often different, that of the left valve right at least in the outer layer, prismatic (similar group Arctinula); hinge margin toothless, in most cases asymmetrical, that of the right valve short or with 2 prolongations, left valve. Animal highly asymmetrical, downwardly displaced by the byssus, the lamellae enclosed by the margin of the the right gill is consisting of identical two-limbed filaments; the small foot has a groove and an anterior pit connected with it it; is affixed to the left valve by a very strong byssal muscle and often, in addition, by a smaller retractor; the moderately strong roundish adductor muscle lies more ventrally; the heart projects out freely, without pericardium, into the mantle cavity; the kidneys are highly asymmetrical, the byssal left one ring-shaped around the musculature, the right one between the adductor and byssal muscles, they are interconnected anterior to the heart; branched ciliated processes are considered to represent the ciliated funnel; the sexes are separate, the gonads asymmetrical, the right one lying largely in the mantle. When the byssus is 1. Shell in most cases smooth or sculptured; reduced, the retractors are absent. Family ANOMIIDAE irregularly roundish, often translucent interior side byssal aperture of the right valve is Anomia (Linne) in and thin, most cases nacreous shiny; the closed in a few groups. Miiller, 1776 Shell as a rule in the right valve with a deep indentation, which is sometimes completely surrounded by the lower margin and is only 1240 seldom reduced; valve with the scar of one or 2 byssal muscles; left ligament short or somewhat elongated by process of the hinge margin of by the the right valve, covered left valve. Several species in various seas. with Subgenus Isomonia Dautzenberg & H. Fischer, 1897. Left valve straight hinge margin, which forms corners at the ends, thin, roundish; ligamental pit very small; scar of the byssal muscle simple, joined with that of the adductor muscle; right valve unknown. A. (Dautzenberg & (/.) alberti H. Fischer), near the Azores. Subgenus Heteranomia Winckworth, 1922. Shell small, thin and smooth or spiny; umbo marginal; byssal muscle simple, transparent, lying over the small adductor muscle; limbs. A. (//.) squamula Linne, gill filaments without ascending in the northern Atlantic Ocean. Subgenus Monia Gray, 1849. Shell of variable size and strength; hinge margin of the right valve sometimes prolonged by processes; the end of the process enclosing the byssal aperture may be fused with the upper margin; byssal muscle simple; gill filaments with two limbs. A. (M.) zelandica Gray. Subgenus Anomia Shell in most cases s. s. (synonym Fenestella (Bolten) Roding, 1798). fairly thin; hinge margin short, without processes; byssal aperture without fused margins; Section Anomia s. being the largest; — byssal musculature bipartite. Muscle scars situated close together, the uppermost byssal aperture fairly large. A. (A.) ephippium Linne. s. Section Patro Gray, 1 849. Scar of adductor muscle larger than that of the upper byssal muscle, the central one small; byssal aperture fairly small. A. (P.) elyros Gray. — Section Enigmonia Iredale, 1918 (synonym Aenigma Koch, 1846, non Newman, 813 oval, umbo of byssal muscle (Fig. 1836). Shell thin, often transversely the left valve not positioned marginally; scar of the large away from the other two. A. (E.) aenigmatica (Chemnitz) 805). Fig. 805. Shell of Anomia (Enigmonia) aenigmatica (Chemnitz). 1241 Subgenus Pododesmus Philippi, 1837 (synonym Tedinia Gray, 1851). Byssal aperture small, sometimes fused with the byssus; hinge margin only slightly elongated; byssal muscle simple. A. (P.) rudis Broderip. Subgenus Placunanomia Broderip, 1832. Shell with few strong zig- zag-shaped folds; byssal aperture closed; right valve with 2 ridges, diverging at an acute angle, separated by a pit; corresponding to these are furrows in the left valve, as bearers of the ligament; byssal muscle simple. A. (P.) cumingi Broderip. Placenta Retzius, 1788 Shell greatly compressed, disk-shaped, often large, more or and translucent, cemented by a byssus only during early free-living, life, less thin thereafter without byssal aperture; surface finely radially sculptured; inner side nacreous shiny, in the center with a roundish adductor muscle, only with a weak foot muscle; the ligament, similar to that in Placunanomia, borne by 2 diverging ridges of the right valve and corresponding furrows of the Few Subgenus Placenta transparent; flat, left valve. species in the Indo-Pacific region. s. s. (synonym Placuna Bruguiere, 1792). hinge ridges diverging at Shell a sharp angle, the anterior shorter than the posterior. P. (P.) orbicularis (Retzius). Subgenus Ephippium (Bolten) Roding, 1798 (synonym Placunema Stoliczka, 1870). peculiarly curved Shell saddle-shaped; hinge ridges diverging at a right angle, equally long. P. (£.) sella (Gmelin). IV. ST1RPS OSTREACEA cemented Shell inequivalve, to solid substrata by the left valve, or less irregularly formed; ligamental cartilage in a triangular pit; more hinge margin toothless; mantle lobes completely separate; foot and byssus reduced; gill lamellae folded, with large inner marginal filaments; the outer ascending lamellae are fused with the mantle; the long ciliated funnels of the kidneys posteriorly lie on the inner side of the outer sacks, which are connected with one another and anteriorly receive the gonoducts. 1. Characters of the Family stirps. The OSTREIDAE shell structure of the two valves in most appears to differ; the ostracum of the right valve shows a sometimes irregular prismatic structure; the left valve is in most cases cases • 1242 deeper than the not seldom Form and right. are the margins exterior sculpture are highly variable, more or less strongly folded. Ostrea Linne, 1758 Synonyms + Peloriderma Peloris Poli, 1795. Characters of the family. warm and temperate seas. Subgenus Lopha (Bolten) Roding, 1798. Animals of separate Several species in 814 more or shell with more Shell strongly inequivalve; folds of the left valve distinct, margin with a row of tubercles. O. (O.) stentina Payraudeau. Lopha s. s. sex; less strong folds. Section Ostreola Monterosato, 1884. (synonyms — inner Section Rastellum (Lister) Schroter, 1782; Alectryonia ? Fischer von Waldheim, 1807; Dendrostrea Swainson, 1840). Valves not greatly differing, with strong folds; inner margin denticulate; left valve sometimes cemented by irregular processes. O. (L.) cristagalli Linne. Subgenus Pycnodonta Fischer von Waldheim, 1834. Sexes separate; lower valve greatly deepended, without folds, the upper one flattened, with wrinkles anterior and posterior to the hinge margin. O. (P.) Lamarck f; the living O. cochlear Poli. Subgenus Crassostrea Sacco, 1897 (synonym Dioeciostraea Orton, vesicularis Sexes separate; shell thick, not folded, with external lamellae; 1928). form often much higher than long. O. ligamental surface high; virginica (C.) Gmelin. According to Dall, O. angulata Lamarck, in most cases included in Gryphaea, belongs here. Subgenus Ostrea s. Monoeciostraea Orten, develop inside the gills s. (synonyms Anodontostrea Suter, 1917; Animals hermaphroditic; the embryos 1928). of the mother; shell roundish or oval; valves not greatly differing. Surface with irregular lamellae; lower valve with folds; umbo O. and straight (O.) edulis flattened. Section Ostrea Linne. — folded. Genotype?, the living O. 3. Order s. Inner margin smooth. 1907. Inner margin puelchana Orbigny. EULAMELLffiRANCHIATA Gill filaments as a rule fused often s. Section Eostrea Jhering, on either side to form 2 perforated, folded laminae. Mantle often with posterior siphons. Anterior adductor muscle seldom reduced. Hinge teeth in most cases few in number, alternating lateral teeth, in in the addition, two valves, often with a often present; however, right central tooth; all hinge teeth may disappear and very seldom be replaced by irregular tooth formations. 1243 Suborder SCHIZODONTA Shell variously formed; the ostracum consists of an inner nacreous and outer prismatic layer the hinge layer; primitively schizodont; is according to more recent opinion, a central tooth valve, situated in front of the center, clasped is present in the right on the anterior simple tooth and a posterior tooth subdivided in addition, the right valve has a posterior, and often an left anterior, in more or left valve by an below by a sinus; less elongated, tooth most cases weak, tooth near the margin; in the valve a posterior elongated tooth present below the margin. In most cases well-developed foot has no byssus; the mantle is in most cases completely open, although sometimes with a septum below the opening, and which can be separated from the supraanal excurrent opening by a bridge; the gill laminae consist of a descending and an ascending lamella, which in Trigonia, similar to that in Area, consist of filaments which are joined only by ciliary tufts; in unionaceans, they are 115 formed of filaments which are more or forming continuous, a lamina are less fused with one another, lattice-like, perforated lamellae; the more or less two lamellae of connected with one another by septa, and the outermost lamellae are in most cases fused to the mantle by their upper margin; the innermost ones often attached to the visceral sack and posterior to it they are fused with one another; the labial palps are well-developed; the heart chamber is nearly always traversed by the intestine. I. STIRPS TRIGONIACEA Shell fairly thick, rounded-triangular; ligament external, fairly short; hinge strong, central tooth especially the triangular, of the left valve; the ridges, only the anteriormost tooth main ventrally distinctly teeth indented with strong transverse of the right valve is a narrow, smooth lamella; the anterior adductor muscle lies close to the hinge teeth and its attachments to the shell are distinctly deepened, whereas the posterior ones are more shallow; foot slightly byssal gland is indicated completely open, to that in only large, anteriorly tongue-shaped, with an only deep groove, into which open 2 rows of large glandular by a narrow although at the posterior fairly cells; a long tube; mantle margin with small papillae; gills similar Area with a rachis and with filaments fused with one another at the margin, without connection with the mantle and visceral sack; the kidneys are similar to those in Area, with strongly branched sacks; the sexes are separate. Marine. i244 Family Characters of the stirps. TRIGONIIDAE The genus Trigonia Bruguiere, of which are variably sculptured, is the species extinct. Neotrigonia Cossmann, 1912 Shell with strong, tuberculate radial folds; N. pectinata (Lamarck). Fig. 806. Few umbo only slightly and ventrally divided. projecting, not posteriorly inclined; tooth 2 high species near Australia (Fig. 806). Internal side of the left shell valve of Neotrigonia margaritacea (Lamarck). II. Shell STIRPS UNIONACEA of medium to considerable sometimes completely reduced, and in size; the Iridina schizodont hinge replaced by a is row of tubercle-shaped teeth; the mantle margins are sometimes completely separated from one another, sometimes variable fused with one another in the posterior part; foot in most cases hatchet-shaped, reduced in Aetheria; the leaf-shaped gills are fused with one another posterior to the is also fused with the mantle, the inner one with them the eggs develop in the female, sometimes in all four laminae, sometimes only in the inner or the outer ones; after they are freed, the embryos almost always live parasitic on fishes. In fresh foot, often the outer one the visceral sack; in waters, distributed over all continents. For distinguishing the families, mainly the behavior of the their relationship to brood care have been used. gills and 1245 816 Shell strong, weak concentric anterior teeth in MARGARITANIDAE Family 1. elongated, anteriorly rounded; fairly sculpture; in the left valve with 2 and with one umbo more or low, with less complete in the right valve; posterior lamellae short, most cases incomplete or totally absent; gills not fused posteriorly with the mantle, forming an incomplete diaphragm; the outer lamina is only anteriorly fixed to the mantle; the anterior end of the inner lamina is separated from the labial palps; the gills have scattered interlamellar junctions, which form irregular rows or oblique continuous places at the posterior mantle margins septa; supraanal opening is absent; glochidia without hooks, in all the 4 are separate, larvae gill are small so that a separate half-circle-shaped laminae. Margaritana Schumacher, 1817 Characters of the family. The genus includes few species in the northern hemisphere. Subgenus Potamida Swainson, 1 840 (Potomida) (synonym Pseudunio Haas, 1910). Posterior hinge teeth distinctly developed, 2 in the in the right valve. M. (P.) sinuata left, 1 (Lamarck) = auricularia (Spengler). Margaritanopsis Haas, 1912, proposed for "Unio" laosensis (Lea) from Indochina, similar. is Subgenus Margaritana s. s. (synonyms Baphia (Meuschen) + Damalis (Leach) Gray, 1847). Posterior hinge teeth rudimentary or absent; M. (M.) margaritifera Subgenus Cumberlandia Ortmann, 1912. without water s.; gills septa. tubes., gills (Linne). Shell as in Margaritana s. with incomplete water tubes and continuous, obliquely descending M. (C) monodonta 2. (Say). Family Shell of highly variable less reduced; UNIONIDAE form and size; umbonal sculpture more or hinge sometimes more or less strongly developed, sometimes completely reduced. The diaphragm formed by the gills is complete; lamina posteriorly fused with the mantle to the end; the incurrent and excurrent apertures are separated from one another by the outer gill diaphragm, the latter is a supraanal opening; parallel to the filaments only the outer gill closed above in most cases and separated from gill lamina with interlamellar septa, which extends and with water tubes; glochidial larvae laminae. in all or 1246 A. Subfamily Unioninae Umbonal sculpture variable, concentric tuberculate, often indistinct; hinge teeth equal. A supraanal opening more or or zig-zag-shaped less strong; or both sexes sometimes not separated from the anal is opening; brood space (marsupium) in all or only the outer laminae, which always have smooth margins; water tubes of gravid females glochidia semi-elliptical undivided; or half-circle-shaped, without hooks. A separation of the groups, which harbor embryos in all gill laminae (Quadrulinae) from those which keep them only in the outer laminae (Unioninae s. not practical at present, because the animals are is s.), unknown in many The Unioninae still genera. live in North and Central America, in Asia, Europe and Africa. Virgus Simpson, 1900 817 solid-walled, compressed, anteriorly shortly rounded, posteriorly greatly produced, almost straight below, with or without Shell fairly wrinkled folds; main teeth small, solid, strongly cuspidate, anterior to that of the right valve with an accessory tooth; lamellae fairly short and low, thin. Gill diaphragm complete; anal opening of the mantle large, combined with the supraanal opening; foot small; inner the visceral sack to the labial palps; the septa, gill gill attached to laminae has no complete but only irregular connective tissue bridges of highly variable length, those in the anterior part of the inner laminae most densely situated and probably indicate that the embryos, which are not known, are received here. Few species on New Section Leiovirgus Posterior beak truncated, (Schepman). — Section wrinkled folds. V. the structure of the to be included (V.) Guinea. Haas, 1912 (synonym Nesonaia Haas, without wrinkled folds. Virgus s. s. V. (L.) 1913). misoolensis Posterior beak fairly pointed, with beccarianus (Tapparone Canefri). Judging from gills, the genus is very primitive and perhaps needs in a separate subfamily. Haas considers it possible that the Australian "Unio" novaehollandiae Gray belongs in this genus; if this is confirmed, then the genus must receive the name Cucumeria Conrad, 1853. The named species is sculptured in the posterior, larger half with irregularly radiating tuberculate folds. 1247 Parreysia Conrad, 1853 Shell umbo fairly small and in most cases inflated, ovoid to rhomboid; elevated, with radial or zig-zag-shaped, sometimes fairly extensive sculpture; left valve with 2 irregular, sometimes strong and striated, and 2 posterior lamellae; right valve with which there may be a second smaller and above an anterior tooth, posterior lamella, at the lower side of which a and a compressed one, sometimes weak, anterior teeth furrow sometimes developed, corresponding is the opposite side. All 4 gill to the lower lamella of laminae contain glochidia; the inner is anteriorly longer and broader than the outer, largely attached to the large foot. Several species in India, China Subgenus Parreysia s. s. (?), and in tropical Africa. Glochidia only slightly higher than broad, with somewhat incurved ventral margin. P. (P.) multidentata (Philippi) = corrugata (Muller) Fig. 807. (Fig. Hinge margin of the 807). left valve of Parreysia corrugata (Muller), enlarged. Subgenus Radiatula Simpson, 1918). Innermost gill 1900 (synonym Indonaia Prashad, lamella completely fused; embryos distinctly higher than broad, with short hinge margin and stronger incurved ventral margin. P. (/?.) species, placed crispisulcata (Lea). by Prashad The group in Indonaia, is erected for the named which accordingly must bear the older name. ? Subgenus Diaurora Cockerell, 1903 (synonym Aurora Simpson, 1900, non Ragonot, 1887, nee Sollas, 1888). Shell small, egg-shaped, sculptured with tubercles and angular folds; anterior teeth truncate cone- shaped. P. (D.) aurorea (Heude), in China. Grandidieria Bourguignat, 1885 Synonym Ruellania Bourguignat, 1885. Shell small, strong, inflated, ovoid to rhomboid; most cases sculptured with fine zig-zag lines, umbo elevated, in which may form tuberculate 1248 ribs mainly anteriorly and posteriorly; often irregular teeth and the left and G. right valve in the right valve. 1 burtoni (Woodward). A valve with left and 2 anterior or 2 anterior, 1 teeth; 2 lamellae in Animal unknown. in Lake Tanganyika. few species Caelatura Conrad, 1853 Synonyms Pharaonia Bourguignat, 1880 (nom. nud.); Zairia + Reneus Rochebrune, 1886; Renatus Rochebrune, 1904. Shell more or less elongated egg-shaped, medium-sized; umbo in most cases with zig-zag ridges and tubercles; anterior hinge teeth thin or tuberculate; lamellae left 2, right than the outer, lamella A is all 1; inner gill lamina broader anteriorly containing small, roundish embryos, the innermost fused to the foot only in the anterior part. few species Pallary, 1924, in the Nile and tropical Africa. proposed as sections: Horusia for C. rugifera (Kuster), Nitia (?) for teretiuscula (Philippi), and Jaronia and nilotica (Cailliaud). ? Subgenus Laevirostris Simpson, 1900. Umbo without distinct stagnorum (Dautzenberg). sculpture; anterior hinge teeth thin. C. (I.) Psilunio Stefanescu, 1896 Synonyms Rhombunio Germain, 1911; Migranaja Hannibal, 1912. Shell fairly strong, somewhat inflated, anteriorly fairly short, rounded, posteriorly angulate; umbo projecting, with fine, fairly parallel wrinkles; somewhat compressed; lamellae straight or weakly curved. Supraanal opening separated from the anal opening; gill laminae anterior hinge teeth with complete and incomplete septa, the outer ones narrower than the inner, all containing embryos; innermost lamella attached only very anteriorly. P. littoralis (Lamarck). A few species in the Near East, central Europe, and the Mediterranean region. Stefanescu based the groups Psilunio, Rytia, and Iridea (non Swainson, 1840) = Cuneopsidea Wenz, 1928, on fossil species. According to Prashad, "Unio" semirugatus Lamarck (called by him Rhombunio) contains embryos only in the outer gill laminae. Rhombuniopsis Haas, 1920 umbo more wavy wrinkles; Shell thick, anteriorly short, egg-shaped; in position, inflated, sculptured with or less anterior anterior teeth massive; lamellae short and strong. Animal unknown. R. tauriformis (Fulton). A couple of species in China. 1249 Schepmania Haas, 1912 Shell fairly solid-walled, elongated oval, with parallel wrinkled folds along the posterior edge; anterior hinge teeth low, bluntly cone-shaped; lamellae short and low. Animal unknown. 5. nieuwenhuisi (Schepman). 2 species in Borneo. In versidens 819 Shell fairly more or strong, Haas , 1911 elongated egg-shaped, anteriorly less short, posteriorly obliquely truncated; right valve with and 2 lamellae, indistinct, /. left one with 2 main one anterior tooth one of which teeth, is sometimes and one lamella. Animal unknown. A brandti (Kobelt). few mainly Japanese species. Pseudobaphia Simpson, 1900 Shell strong, short egg-shaped, inflated, anteriorly rounded, posteriorly somewhat truncated; umbo elevated; anterior teeth cuspidate; lamellae very small and weak. P. strong, strongly Animal unknown. biesiana (Heude), in China. Lamprotula Simpson, 1900 Synonym Gibbosula Simpson, Shell surface 1900. roundish to egg-shaped; thick, umbo sculptured with tubercles and ridges; anterior in anterior teeth position; strongly furrowed; 2 strong, transversely furrowed lamellae in both vales. Gills similar to those in Psilunio; marsupia not sharp at the all 4 laminae forming pillow-shaped margins; innermost lamella attached only very anteriorly. L. plumbea (Chemnitz). A few species in China. Discomya Simpson, 1900 Shell posteriorly strong, compressed, roundish, anteriorly shortly rounded, somewhat truncate; umbo low; surface with numerous tubercles, in the posterior part sculptured with bulging folds; right hinge tooth fairly broad, triangular, high, somewhat furrowed; posterior one longish, anterior tooth of the weak. Animal unknown. D. radulosa (Drouet & left valve low; lamellae short and fairly Chaper). 2 species on Borneo. 1250 Pseudodon Gould, 1844 Synonyms Monocondylus Morelet, 1886; Pseudodus Morgan, 1885. Shell more or less elongated egg-shaped; umbo situated fairly far forward, only slightly projecting, with W-shaped wrinkles which are seldom retained; each valve with a tubercle-shaped anterior tooth; posterior lamellae rudimentary or absent. Mantle in most cases with a supraanal opening; inner and outer Greater Sunda laminae containing embryos. gill Burma and Several species in Indochina to south China and on the Islands; one- in Japan. Section Trigonodon Conrad, 1865. Shell strong; right valve with a strong triangular tooth, posterior to latter — weak with a indication tooth; left from the anal anterior third. P. with a distinct pit and behind the valve with a strong triangular tooth and of a tooth anterior to Section Indopseudodon separated it it. Prashad, P. innermost one; A opening supraanal gill — salwenianus (Gould). (I.) (Anthony). crebristriatus (T.) 1922. not is lamella attached in the Section Pseudodon s. s. (synonyms Monodontina Conrad, 1853; Suborbiculus Simpson, 1900). Shell compressed, anteriorly lower than posteriorly; each valve with a smooth tooth parallel to the margin; inner lamella not fused with the foot for 2/3 of 820 — = vondembuschianus (Lea). elongated egg-shaped, fairly thin, folds, the of the inner lamina gill its length. P. (P.) inoscularis (Gould) Section Obovalis on Simpson, 1900. Shell the edge of the area with V-shaped upper limbs of which cross the area, whereas the lower ones extend over the external surface; hinge teeth high, triangular. P. (O.) loomisi Simpson. — Cosmopseudodon Haas, 1920. Section elongated, solid-walled, umbo Shell fairly with 2 V-shaped folds, gradually becoming more wavy; posterior part of the shell with radial folds, which in most cases become indistinct in adult animals; hinge teeth thick and blunt. P. (C.) resupinatus Martens. — Section Diplopseudodon Haas, elongated rhomboid, thick-walled; right valve with hinge tooth. P. (D.) crassus Drouet. — umbo — Section Chryso- Shell small, rhomboid, solid- walled the center, with projecting, 1900. not projecting; hinge teeth compressed, high. P. (N.) nankingensis (Heude). umbo approaching Shell with one, Section Nasus Simpson, Shell strongly elongated, moderately thick; pseudodon Haas, 1920. 1920. left 2, wavy and inflated; wrinkles; area broad; hinge tooth of the right valve triangular, parallel to the margin, that of the left valve obliquely directed. P. (C) aureus Heude. Bineurus Simpson, 1900. Shell longish rhomboid, posteriorly compressed, thin-walled; edges of the area P. {B.) mouhoti (Lea). distinct; — Section fairly high, hinge teeth low. 1251 Trapezoideus Simpson, 1900 anteriorly shortly rounded, trapezoidal, Shell broadly truncated; umbo posteriorly higher, only slightly projecting, with zig-zag-shaped weaker sculpture; right valve with a lamella-shaped anterior tooth and a one above it and a posterior lamella; shaped tooth and posterior to lamellae. Outer it left valve anteriorly with a lamella- a wart-shaped tooth and 2 posterior lamina anteriorly narrower than the inner, the gill innermost lamella fused with the visceral sack for 2/3 of 4 laminae containing embryos; supraanal opening T. foliaceus (Gould). A few species in its length; all separate. Indochina and Sumatra. Ensidens Frierson, 1911 Shell elevated, more or less long, fairly smooth or with weak zig-zag thin, posteriorly pointed; lines; area right valve with 2 sharp anterior teeth, left umbo without distinct edges; one with a very long and sharp anterior tooth, a rudimentary tooth below the umbo; lamellae very long and thin. Supraanal opening separated; innermost fused with visceral sack; A few species lamella not gill 4 laminae containing embryos. all Indochina. in Section Uniandra Haas, 1912. Shell egg-shaped, posteriorly scarcely pointed, inflated; umbo elevated, with zig-zag-shaped concentric ridges, E. (JJ.) inaequalis (Rouchebrune). umbo posteriorly pointed; — Section Ensidens without sculpture. E. (£.) s. s. Shell ingallsianus (Lea). Rectidens Simpson, 1900 Shell elongated, posteriorly prolonged, fairly solid-walled; umbo only slightly elevated, with concentric sculpture only on the outermost edges of the area tips; teeth distinct, keel-like; right and a posterior lamella, lamellae; the left valve with 2 anterior thin one with 2 anterior and 2 posterior smaller anterior tooth lies below the umbo. Supraanal opening separated from the anal aperture by a narrow bridge; innermost gill 821 lamella attached to visceral sack only very anteriorly; the laminae are narrow, the outer ones anteriorly considerably shorter and narrower than the inner ones, all containing embryos, the incurved ventral margin of which bearing regularly arranged small tubercles. R. prolongatus (Drouet). and Borneo. A few species in Malacca, Sumatra, Java 1252 Ctenodesma Simpson, 1900 Synonym Chris tadens Simpson, 1914. Shell fairly thin, elongated egg-shaped, compressed; which merge projecting, with delicate zig-zag ridges folds; anterior teeth longish or triangular, low, umbo into scarcely small radial furrowed or deeply cleft; lamellae short and low. Animal unknown. borneense C. A (Issel), on Borneo. change of the generic name because of Ctenodesmus O. F. Cook, 1896, seems superfluous. Balwantia Prashad, 1919 Shell greatly elongated, moderately long anterior to the rounded anteriorly, posteriorly greatly elongated, anteriorly, umbones, distinctly higher than obliquely truncated at the end; hinge teeth rudimentary. Supraanal opening separated; very long and narrow; innermost gills lamella fused to the visceral sack for a considerable length; all 4 gill laminae containing roundish embryos; foot very strong. B. soleniformis (Benson), in Assam. Lamellidens Simpson, 1900 Shell moderately elongated, posteriorly pointed with umbo edge; zig-zag-shaped or nearly concentric; left and 2 posterior lamellae, right anterior teeth teeth low posterior with curved radial ridges, which are sometimes somewhat valve with 2 one with 2 and one lamella. Supraanal opening separate. posterior part broader than anteriorly; visceral sack over a fairly long distance; compressed parallel anterior Gill laminae in the innermost lamella fused to the embryos contained either in all or only in the outer laminae. L. marginalis (Lamarck). Few species in India. Simpson designated Spathopsis Simpson, 1900, as a subgenus of Lamellidens; umbo fairly low, with concentric wrinkles and weak folds anterior and posterior to them; hinge teeth greatly elongated. Animal unknown; systematic position uncertain. S. guillaini (Recluz), in Somaliland. Contradens Haas, 1913 Synonym Schizocleithrum Haas, 1913. 1253 Shell more truncated; umbo or less elongated egg-shaped, posteriorly obliquely occasionally extending over the entire shell; teeth one behind the and 2 lamellae; wavy only slightly projecting, with other, the posterior concentric wrinkles, valve with 2 anterior left of which sometimes disappears, one over the other right valve with 2 anterior teeth lying and one lamella; the teeth are lamellae-shaped, sometimes sharp, sometimes thickened. Supraanal opening separated from the anal one by a narrow bridge; gill laminae broadened in the centre; innermost lamella embryos are contained in anterior half fused with the visceral' sack; in the outer laminae and part of the inner ones; the egg-shaped glochidia have rows of small tubercles on the incurved ventral margin. several C. contradens (Lea). A few species on Sumatra. Caudiculatus Simpson, 1900 822 Shell egg-shaped, inflated, anteriorly rounded, posteriorly oblique and below left it truncated straight; right valve with an anterior tooth and a lamella, one with 2 teeth and 2 lamellae. Animal unknown. caudiculatus (Martens), on Borneo. C. Pressidens Haas, 1910 Shell egg-shaped, thin; umbo low, sometimes with concentric wrinkles; both valves with a long, compressed lamella; posterior tooth above the right and upper lamella of the anterior tooth there wavy main tooth and a long low may be a left valve rudimentary; weak accessory tooth. Animal unknown. moellendorfjl Haas. P. Few closely related species on Borneo, Palawan and Banguey. Acuticosta Simpson, 1900 egg-shaped; Shell concentric serrated wrinkles; umbo strongly projecting, anterior hinge teeth or notched; strong, with zig-zag-shaped compressed, dorsally lamellae short and strong. separated from the anal one by a fairly narrow bridge; Supraanal opening laminae broad; gill innermost lamella largely fused to the foot; the outer gills contain roundish glochidia, which on the ventral side have a rectangular plate with 2 rows of pointed small warts and a few rows of very small granulations. A. chinensis (Lea). Few species in China. 1254 Protunio Haas, 1913 Shell rounded rhomboid, with somewhat wavy solid-walled, posteriorly truncated; umbo wrinkles; anterior hinge tooth of the right valve low, rectangular to triangular; left valve with 2 teeth, the anterior one lamella-shaped the posterior one low, trigonal, furrowed above, and with 2 lamellae which become thicker posteriorly. Animal unknown. P. messaged (Bavay & Dautzenberg), in Tonkin. Elongaria Haas, 1913 Shell elongated, anteriorly rounded, posteriorly obliquely truncated; umbo on the not projecting, without sculpture; anterior hinge teeth fairly weak, right with one accessory tooth; lamellae long. Animal unknown. s. s. Shell medium-sized, moderately solid-walled, Section Elongaria smooth; anterior teeth broadly lamellae-shaped E. (E.) orientalis (Lea), on Java. Section Nannonaia Haas, 1913. Shell small, thin, sculptured — with fine wrinkles in the posterior part; anterior teeth thin, sharp. E. (N.) trompi (Drouet & Chaper), on Borneo. Simpsonella Cockerell, 1903 Synonym Dalliella Simpson, 1900, non Cossmann, 1895. more or less elongated, thin-walled, fairly inflated, anteriorly short and rounded, posteriorly truncated or somewhat pointed; umbo somewhat projecting, with concentric wavy wrinkles; hinge teeth Shell rudimentary, on either side with a lamellae-shaped main tooth and a short, very low lamella, or completely absent. Mantle bridge between the anal and supraanal openings fairly short, deeply sunken; gills moderately 823 broad, with complete septa; innermost lamellae largely fused with the visceral sack; the outer laminae contain triangular glochidia, which have pointed hooks beset with spinules on the outer side. S. purpurea (Valenciennes). Few species on the Philippines (Luzon and Panay). Pilsbryoconcha Simpson, 1900 Shell elongated, thin, and more or concentric less pointed, wavy anteriorly shortly rounded, compressed; umbo posteriorly long scarcely projecting, with wrinkles; hinge margin narrow, non-denticulate. Animal unknown. P. exilis (Lea). A few species in Indochina and on the Sunda Islands. 1255 Schistodesmus Simpson, 1900 Shell strong, roundly triangular, anteriorly steeply sloping, posteriorly oblique, pointed at the end, with concentric bulges; positioned, high, inflated; umbo nearly centrally of the right valve high and anterior tooth strong, triangular, with a furrow in the center; posterior lamella thick; left valve with a lamella-shaped anterior tooth and a thick tooth below the umbo; lower lamella stronger than separate; gills upper. the broad, with complete septa; Supraanal opening innermost lamella attached only very anteriorly; the outer laminae containing the embryos. lampreyanus (Baird S. & Adams), China. in Unionella Haas, 1913 Shell small and thick, short, anteriorly very steeply sloping, posteriorly umbo obliquely truncated; wrinkles; anterior tooth projecting, of the right with concentric zig-zag inflated, valve tri- or quadrangular, low, furrowed above; below the lamella with an accessory lamella; anterior main tooth of the blunt, triangular; valve small, lamella-shaped, the posterior one left lamellae short and strong. Animal unknown. & fabagina (Deshayes U. Jullien). 2 species in Indochina. Physunio Simpson, 1900 Synonym Lens Simpson, Shell fairly thin, in posteriorly elongated and wrinkles on the 1900. most cases inflated, and low, anteriorly short sometimes very high; umbo with zig-zag tips; anterior tooth of the right valve lamella-shaped with a similar accessory tooth above it; anterior main tooth of the left valve long and lamella-shaped, the posterior one small, wart-shaped, sometimes lost; lamellae short, an accessory lamella Supraanal opening small; gills broad, is sometimes formed with age. with simple septa; innermost lamella largely fused with the visceral sack; embryos in the outer laminae. Section Physunio (Lea). A few species s. s. Shell in in Indochina Velunio Haas, 1920. Shell flat, most cases inflated. P. (P.) and on the Sunda Islands. gravidus — Section very high. P. (V.) velaris (Sowerby), in Assam. Prohyriopsis Haas, 1914 Shell elongated oval, thin, compressed, anteriorly very short, posteriorly elongated and beaked; umbo scarcely projecting, without 1256 distinct sculpture; posterior to edge of the area with small longitudinal folds; right anterior tooth lamella-shaped; a similar anterior tooth in the 824 left and umbo valve and below the straight. a higher, leaf-shaped tooth; lamellae long Animal unknown. P. stolata (Martens), in Danau Baru Lake on Sumatra. Hyriopsis Conrad, 1853 Shell large, compressed, posteriorly obliquely truncated and with a wing, sometimes also with a small wing dorsal umbones low, with small concentric at the anterior end; folds; left valve with 2 to 3, right with 1—3 anterior hinge teeth, which are compressed in young shells, in older shells frequently divided into irregular denticles; lamellae long, 2 left, Animal unknown. A few species Borneo and Japan. right. 1 in Indochina H. delphinus (Gruner). each in and China, one Prisodontopsis Tomlin, 1928 Synonym Pseudavicula Simpson, 1900, non Jack & Etheridge, 1892. Shell similar to that in Hyriopsis, with a broad posterior and a small, pointed anterior wing; lamellae, right valve with an elongated anterior tooth and 2 left one with 2 teeth and one long, thin lamella. Animal unknown. P. Meru johnstoni (E. Smith) in Lake (Africa). Chamberlainia Simpson, 1900 Synonym Simpsonia Rochebrune, 1905. Shell very large and thick, roundish, in the wing; anterior hinge teeth fairly small, blunt, separated from the teeth, 1 right, 2 left, 1 young with a posterior right, 2 left; lamellae short, the lower one larger. Animal unknown. C. hainesiana (Lea). Few species in Siam. Scabies Haas, 1911 Shell fairly solid-walled, moderately large, elongated anteriorly rounded, posteriorly long ridges or rows of tubercles, the most of the a median of which continue V-shaped over shell; anterior to the weak lamella-shaped accessory main tooth of the scobinata (Lea). Few right valve there is tooth and below the lamella there accessory lamella. Animal unknown. S. elliptical, and pointed; umbo with radiating species in Indochina. is an 1257 Arcidopsis Simpson, 1900 Shell fairly thick, longish, obliquely sloping anterior to the posteriorly elongated and obliquely truncated; umbones, surface radially striated; umbo only slightly projecting, somewhat inflated with fine radial wrinkles; right valve with an anterior and a posterior accessory tooth and one on the left with 2 Animal unknown. teeth lamella, A. footei (Theobald), in and 2 lamellae; the teeth are striated. India. Ptychorhynchus Simpson, 1900 Shell fairly umbones low, anteriorly rounded, long, in posteriorly pointed, valve with 2 fairly blunt, rough anterior teeth and right strong; the posterior part with radiating wrinkled folds; one with a blunt tooth and an irregular, 1 left or 2 lamellae; the sometimes cleft lamella. Animal unknown. P. pfisteri (Heude). A few species in China. Oxynaia Haas, 1913 825 Shell solid-walled, anteriorly short and roundish, posteriorly less elongated and pointed; umbones more or distinctly elevated, with concentric zig-zag lines; main tooth of the right valve rectangular, deeply furrowed; accessory tooth very small, lamella-shaped; anterior main tooth of the left valve narrowly rectangular, posterior sharp and deeply furrowed above; main tooth pyramidal, often thicker than the anterior one; lamellae long, those of the right valve often with a thin accessory lamella. Animal unknown. O. jourdyi (Morlet). A few Indochinese species. Unio Retzius, 1788 Synonyms Lymnium Oken, 1815; Mysca Turton, 1822; Canthyria Swainson, 1840; Nodularia Conrad, 1853. Shell oval or more elongated, not inclined; umbones in most cases somewhat projecting, with zig-zag which are in most cases not continued not very close to the anterior end and ridges or 2 rows of tubercles, further; right valve with a moderately strong anterior tooth and one lamella, the left one with 2 teeth and 2 lamellae. Supraanal and anal mantle openings separated; innermost septa of the outer gill gill lamella fused only anteriorly; lamina, which contains the embryos, more dense than in the inner lamina; glochidia in most cases with pointed, externally spinulose hooks. 1258 A few species Prashad, Europe, and Africa. in Asia, 1919, erected the subgenus Eolymnium for U. terminalis Bourguignat living in Jordan; the shell has a very short anterior similar to that in Psilunio; the foot contains the embryos, is is weak; the outer gill part, lamina, which considerably narrower than the inner; glochidia not known. Subgenus Cafferia Simpson, 1900. Hinge teeth fairly strong; glochidia triangular, but without hooks. U. (C.) caffer Krauss. A few South African species. Lanceolaria Conrad, 1853 Shell short, greatly elongated, solid-walled, sword-shaped; anterior part umbones low, with radial rows of small which seldom continue further downward; anterior hinge teeth the posterior pointed; tubercles, plump, deeply furrowed above, smooth below; accessory teeth may be present anterior and posterior to them; lamellae long and thick. Animal unknown. A few species in eastern Section Lanceolaria (Lea). —Section s. s. Asia (Indochina to Japan). grayana 1930 (synonym Cylindrica Shell laterally compressed. L. (L.) Pericylindrica Tomlin, Simpson, 1900, non Clessin, 1882). Shell nearly cylindrical, anteriorly very short, posteriorly very long. L. (P.) cylindrica (Simpson). Cuneopsis Simpson, 1900 Shell strong, anteriorly rounded, posteriorly and pointed; umbones situated fairly far more or forward, less elongated distinctly elevated, with few strong, nearly parallel, often tuberculate bulges; left valve below the umbo with 2 main teeth separated by a deep triangular pit; the right one with a strong triangular main tooth and often a small, low tooth posterior to the C. pit; lamellae granulose striated. Animal unknown. celtiformis (Heude). Few species in China and one in Tonkin. Arconaia Conrad, 1865 826 Shell strong, greatly elongated, twisted around the longitudinal axis and in most cases with posterior part curved to the right or left, most cases pointed and also beaked anteriorly; umbones posteriorly in low, situated far forward; right valve with an accessory tooth, which separated from the cleft main tooth by a rectangular accessory lamella; A. left pit, valve with 2 teeth and 2 strong lamellae. contorta (Lea), in China. is and with a weak 1259 Gonidea Conrad, 1857 Shell strong, fairly inflated, elongated triangular, posteriorly much higher than anteriorly, in most cases with a distinct edge to the lower corner; umbones fairly sharp, but not high, with a few strong concentric wrinkles; hinge with a rudimentary tooth and a lamella in each valve. The 4 gill mainly at laminae contain embryos; the septa are often interrupted, the upper and lower margins, and shorter septa may be interposed between them; glochidia roundish, without hooks. G. angulata (Lea), in the western United States of North America. Fusconaia Simpson, 1900 Synonym ? Syntoxia 1820 (Sintoxia). Rafinesque, Shell short elliptical, roundish, rhomboid-shaped or triangular, with elevated umbones, which have few parallel wrinkles; the remaining surface smooth; hinge teeth strong. Bridge between anal and supraanal openings very short, often absent; all gill laminae are marsupial, with nearly cylindrical egg sacks; glochidia small, oval, without hooks. F. trigona (Lea). A few species in the United States. Quincuncina Ortmann, 1922 Shell medium-sized, anteriorly rounded, posteriorly obliquely truncated; umbones only slightly projecting, with nearly concentric farther on become zig-zag-shaped and merge into alternately ridges, which placed tubercles; both valves with 2 cardinal teeth, the posterior of which is larger; is sometimes left valve with 2 lamellae, the right with one which however The 4 cleft. gill laminae are marsupial; the egg sacks scarcely compressed; innermost lamella attached only at the anterior end. Q. burkei Walker, in the United States. Quadrula Rafinesque, 1820 Shell longish, quadratic or rounded or triangular, strong, inflated; posterior edge in most cases distinct; umbones with few irregular, parallel the ridges; sculptured; hinge margin broad; in the right valve, 2 in the left. main projecting, in most cases remaining surface smooth or teeth strong, furrowed; one lamella Bridge between the anal and supraanal openings short, sometimes absent; innermost gill lamella free; all 4 laminae contain embryos; the egg sacks compressed; glochidia somewhat oval, without hooks. 1260 A few species According to in the United States. Herrmannsen, the typical species is Q. quadrula (Rafinesque), and of Theliderma Swainson, 1840: metaneura (Rafmesque); the latter is considered as a section. Amphinaias Crosse 1894 [couchiana (Lea)] may & P. Fischer, also represent a section. Frierson, 1927, recognized the following as subgroups of Quadrula: 827 Quadrula s. s. for quadrula Rafinesque; Tritogonia L. Agassiz, 1852, for verrucosa (Rafinesque); Pustulosa (= Bullata non Jousseaume, 1875) for Quincuncina Ortmann, 1922, for burkei Walker; Luteacarnea (= Striata non O. Boettger, 1878) for striata (Rafinesque); pustulosa (Lea); Orthonymus L. Agassiz, 1852, for cylindrica (Say); Cyclonaias Pilsbry, 1922, for tuberculata (Rafinesque); Obliquata for obliquata (Rafinesque); Fusconia (err. pro Fusconaia Simpson, 1900) for undata (Barnes); and Pleuronaia for barnesiana (Lea). Amblema Rafinesque, 1819 Synonyms Bariosta Rafinesque, 1831; Crenodonta Shell large, Schluter, 1838. roundly oval, with far forwardly situated umbones, which are sculptured with concentric wrinkles; posterior part of the shell in most cases with broad radial folds. Bridge between the anal and supraanal openings very short or absent; innermost 4 gills gill lamella free; all marsupial; egg sacks compressed; water tubes of the inner laminae somewhat wider than those of the outer laminae; glochidia small, oval, without hooks. A few species in the United States Amblema Section s. s. Umbonal and Mexico. sculpture not extending over the — A. (A.) costata Rainfesque. Section Megalonaias Utterback, The zig-zag-shaped umbonal sculpture extends over the surface in the form of tuberculate folds. A. (M.) heros (Say). Section Psorula surface. 1915. — Haas, 1930. Umbones with many densely placed, wavy, which merge into the warty or granulose scaly sculpture of the external surface, which also in most cases shows strongly bulging growth lines. A. (P.) rudis (Simpson). In addition, Frierson concentric projecting, wrinkles, mentions Plectomerus Conrad, 1853, for A. dombeyana (Valenciennes). Walker recognizes Cokeria Marshall, 1916 an abnormal shell of Amblema (southalli Marshall), as costata. Tritogonia L. Agassiz, 1852 ? Synonym Ellipsaria Rafinesque, 1820. Shell strong, in the female distinctly longer than in the male, with a posterior obliquely descending bulge, warty anterior to it; umbones 1261 fairly low, with strong, irregular, nearly parallel bulges and with fine and posterior radial ridges anterior to these; hinge teeth strong, furrowed; lamellae long and straight. Supraanal opening long; in the female the mantle forms a thickened lobe in the posterior part, at the inner side which hangs a smaller lobe; inner laminae gill outer ones; innermost lamella largely free; T. all much broader of than the 4 laminae marsupial. tuberculata (Barnes), in the United States. Rotundaria Rafinesque, 1820 Shell roundish; umbones projecting, with numerous fine, irregular, discontinuous roughenings, the posterior 3 fifths of the surface warty; nacre purple-colored. opening; gill Supraanal opening not separated from the anal laminae broad; innermost lamella much more densely-spaced contains 828 septa than the free; the outer lamina has inner lamina and alone embryos. According to Herrmannsen, Obliquaria subrotunda Rafinesque is to be considered as the typical species, whereas Simpson considers O. tuberculata Rafinesque as such. A few species in Central and North America. Psoronaias Crosse Shell fairly variable, & Fischer, P. 1893 most cases somewhat in triangular, with projecting umbones; surface with small warts and sometimes posteriorly with a few folds; anterior hinge teeth of the right valve unequal, the upper one weak, compressed, the lower one thick and grooved. Animal? P. psoricus (Morelet). A few species in Central America. Plethobasus Simpson, 1900 Shell warts; and strong, irregularly oval, large high, with a main few strong teeth triangular, the anal opening Umbones by a very narrow bridge; only the outer aesopus (Green), fairly row of broad and flat rough. Supraanal opening separated from which have much more densely-spaced P. inflated. folds; outer surface with a in the septa, gill laminae, are marsupial. United States. Pleurobema Rafinesque, 1820 Synonyms ? Scalenaria + Aximedia Rafinesque, Shell strong, triangular or rhomboid, in umbones which are situated more or 1820. most cases with projecting less far forward, and are sculptured 1262 with few, often interrupted folds; a rounded posterior edge is present; hinge teeth double in both valves. Supraanal opening separated from anal opening by a narrow bridge; outer fairly gills marsupial. mytiloides Rafinesque (= Unio clava Lamarck). Several species P. United States. in the Lexingtonia Ortmann, 1914 rounded quadrangular; umbo only Shell slightly elevated, situated almost in the center, with fairly densely placed, parallel wrinkles which form an indistinct angle at the posterior anterior to outer it; from the anal opening; glochidia without hooks. distinctly separated subplana (Conrad), in the United States. 1819 Elliptio Rafinesque, Synonyms Eurynia Rafinesque, 1820; Eurynaia Cunicula Swainson, Shell The laminae have cylindrical, red egg sacks; supraanal opening gill L. edge and are somewhat wavy surfaces smooth; hinge teeth well developed. lateral more or Frierson, 1927; 1840. umbo rhomboid-shaped; less elongated, oval to with few, fairly strong, parallel wrinkles; lateral surfaces smooth. Supraanal opening separated from the anal opening; innermost gill lamella free; the outer lamina marsupial; glochidia small, without hooks. Several species in North and Central America. Section Elliptio s. s. Shell only slightly elongated; posterior edge smooth. E. (E.) crassidens (Lamarcq 1 )- — Section Micronaias Simpson, (M) 1900. Shell small, distinctly concentrically striated. E. — Section Canthyria Swainson, posterior edge; 829 spinosa (Lea). elongated; E. ((/.) 840. Shell with a arata (Lea). row of spines on the hinge teeth fairly compressed; lamellae short. E. (C.) — umbo 1 Section Uniomerus Conrad, 1853. Shell distinctly scarcely projecting; hinge teeth in most cases compressed. tetralasma (Say). — Section Nephronaias Crosse & P. Fischer, 1893 (synonyms Leptonaias + Simonaias + Caenonaias + Graphonaias Crosse & P. Fischer, 1893). Shell elongate oval to kidney-shaped; hinge teeth short and strong. E. (N.) plicatula (Charpentier). — Section Popenaias Frierson, 1927. Shell long, anteriorly low; hinge teeth compressed, sharp. — E. (P.) popei (Lea). Section Barynaias Crosse & P. Fischer, 1893 (synonym Sphenonaias Crosse & P. Fischer, 893). Shell strong, somewhat 1 This is a typographical error in the original; read Lamarck. — Editors. 1263 trapeze-shaped; anterior hinge teeth thick. E. (B.) pigerrima (Crosse P. & Fischer). Because Herrmannsen designated Unio dilatatus Rafinesque, which is to = Elliptio gibbosa (Barnes) as the genotype of Eurynia, Eurynia has be considered as a synonym of [sloatianus (Lea)], named 1927 Elliptoideus Frierson, Elliptio. as a subgenus of Elliptio, has eggs in all 4 gill laminae. In addition, 1927, has proposed the following groups: Frierson, Reticulatus for E. reticulata (Simpson) with net-shaped sculptured surface, rubicunda (Martens) with coarse concentric Martensnaias for E. and strong hinge teeth, and Nephritica for poeyana E. striae (Lea). Hemistena Rafinesque, 1820 Synonyms Odatelia Rafinesque, 1832; Hemilastena 1852; ? Sayunio Gregorio, Shell fairly strong, posteriorly pointed; Agassiz, considerably elongated, anteriorly rounded, umbo low, with few irregular longitudinal smooth; one rudimentary hinge tooth sides L. 1914. in each valve; folds; lamellae scarcely indicated. Foot very large; only the median part of outer marsupial; glochidia half-circle-shaped, with gill unequal sides, without hooks. H. lata (Rafinesque), in the United States. B. Subfamily Anodontinae Shell often thin, more or less elongated; umbonal sculpture concentric or biseriate; hinge teeth in most cases incomplete or absent. Supraanal opening of the mantle a broad bridge; tripartite outer in most cases separated from the anal opening by gill laminae marsupial, in gravid females with water tubes, of which only the middlemost serves as an egg sack; glochidia half-circle-shaped or triangular, with hooks on the ventral side; during winter they remain within the maternal Frierson distinguishes the gills. subfamily Alasmidontinae from the Anodontinae. Arkansia Ortmann Shell & B. Walker, 1912 moderately thick, inflated, only slightly elongated; elevated, with 2 or 3 double rows of ridges umbo which are not continuous with the sculpture of the lateral surfaces; hinge well developed, with strong main teeth and fairly short lamellae. A. wheeled Ortmann & Walker, in the United States. 1264 Arcidens Simpson, 1900 formed Shell similarly to that in Arkansia; irregular wrinkles in 2 rows, with warts with very strong, lateral umbones with fine small radial folds; left valve with 2 compressed, elongated main teeth, the posterior of which lying below the umbo is upwardly curved and bisects the right and posterior surfaces; anterior 830 umbo which continue onto the to the hinge margin, which has a compressed tooth; lamellae numerous, short, irregular. A. confragosus (Say), in the United States. Alasmodonta Say, 1818 (Alasmidonta) Synonyms Monodonta Schluter, Say, 1816 (non Lamarck, 1801); ? Anadontina 1838; Uniopsis Swainson, 1840; Anelasmodonta Herrmannsen, 1846. Shell most cases rhomboidal, usually with a in inflated, posterior edge to the lower corner; somewhat left valve with 2, right with one main few species in the United States. Section Prolasmidonta Ortmann, 1914. strong; distinct elevated, with concentric or most cases incomplete or absent. tooth; lamellae in A sculpture; biseriate umbo Umbonal sculpture moderately an angle on the posterior edge; hinge lamellae ridges with one in the present, 2 in the right, — Section Alasmodonta s. s. left valve. A. (P.) heterodon (Lea). Shell strong, inflated, moderately elongated, with very strong, in most cases concentric umbonal sculpture; main teeth strong, blunt; lamellae short, very incomplete or absent. A. (A.) undulata (Say). — Section Bullella somewhat Simpson, 1900. with sharp edge; triangular, Shell umbo thin, greatly inflated, strongly projecting, with very strong concentric sculpture; main teeth compressed and recurved. A. (B.) arcula (Lea). — Section Decurambis Rafinesque, 1831 (synonym Rugifera Simpson, 1900). Shell elongated, inflated, posterior to the edge with radiating wrinkles; teeth very incomplete; lamellae absent. A. (D.) atropurpurea Rafinesque. — Section Pressodonta Simpson, 1 900 (synonym Calceola Swainson, 1840, non Lamarck, 1801). Shell small, elongated; umbo — with weak wrinkles; teeth compressed. A. (P.) calceolus (Lea). Section Pegias Simpson, 1900. Shell small, with 2 posterior bulges; umbo with somewhat cone-shaped wrinkles; hinge teeth fairly strong; lamellae absent. A. (P.) fabula (Lea). 1265 Lasmigona Rafinesque, 1831 compressed; Shell one, the left umbo low, with strong ridges; right valve with with 2 hinge teeth, the posterior of which bisects the right hinge margin; lamellae in most cases incomplete. A few species in the United States. 1917. Shell moderately strong, smooth, Section Platynaias Walker, umbonal sculpture sharply biseriate; hinge teeth weak; lamellae Section Lasmigona s. s. Shell compressed. L. (P.) compressa (Lea). with posterior folds; umbo with several coarse wrinkles, in most cases somewhat biseriate and often with radial wrinkles in front and behind; longish; — hinge lamellae consisting of irregular oblique ridges. L. (L.) costata (Rafinesque). — Section Sulcularia Rafinesque, 1831 (synonym Alasminota Ortmann, 1914). Shell fairly small, distinctly elongated, umbo smooth; with 4 or 5 fairly fine, sharp ridges, the median of which are sharply biseriate; hinge teeth weak; lamellae scarcely developed. L. (Rafinesque) = holstonia (Lea). — (synonyms Complanaha Swainson, 1840; Shell large, badium (S.) Section Pterosyna Rafinesque, Megadomus Swainson, ? high and inflated in the posterior part; umbo 1831 1840). greatly compressed, with sharp biseriate sculpture; hinge teeth strong. L. (P.) complanata (Barnes). Simpsoniconcha Frierson, 1914 831 Synonym Simpsonaias Shell elevated, center; small, 1914. Frierson, elongated oval; umbo fairly sharp, but only slightly with fine parallel ridges which are upwardly curved in the an irregular compressed tooth each valve; lamellae scarcely in developed. S. ambigua (Say), in the United States. Anodontoides Simpson, 1898 Shell thin, inflated, longish, with weak posterior edge; umbo bulging, with few concentric, abruptly upwardly arched wrinkles, posterior to which are fine radial wrinkles; lateral surfaces smooth; hinge teeth scarcely indicated. A. ferussaciana (Lea), in the United States. Lepidodesma Simpson, 1896 Shell large, thin, inflated, elevated, with concentric folds, with 2 posterior edges; which continue over the umbo greatly entire shell, in 1266 addition 2 rows of tubercles are developed; ligament very strong; left valve with 2 main teeth, the anterior of which elongated, internally is crossing the hinge margin and terminating abruptly, whereas the posterior one shorter and narrower, and with 2 strong lamellae; right valve with is a low anterior tooth, and an upwardly curved lamella. Animal unknown. languilati (Heude). 2 species in China. L. Cristaria Schumacher, 1817 Synonyms Barbala Mus. Calonn., 1797, Dipsas Leach, 1814, non 1768; Appius (Leach) Menke, 1830; Dianisotis Rafinesque, Laurenti, 1831; Cleone Gistel, Shell in 1848. most cases thin, moderately elongated, sometimes with a wing-shaped process; umbo low, initially with biseriate wrinkles, thereafter with lateral surfaces concentric flat —on rudimentary ridges; either side with a smooth; hinge teeth — compressed tooth or absent; lamellae simple, often absent in adult shells. A few species in eastern Asia. Section Crassitesta Simpson, without wings; umbo somewhat 1900. Shell weak. C. (C.) radiata Simpson. with flat (P.) discoidea (Lea). and lamellae very — Section Pletholophus Simpson, 1900. umbo compressed, medium-sized, anteriorly scarcely thickened; Shell small and strong, fairly projecting; hinge teeth concentric wrinkles, scarcely winged; hinge teeth very weak. C. — Section thickened, posteriorly winged, Cristaria in s. s. Shell anteriorly large, with the posterior part weak radial bulges and a row of folds. C. (C.) plicata (Leach). Leguminaia Conrad, 1865 umbo situated more or somewhat biseriate wrinkles; sides fairly smooth, in each valve with one smooth tooth, the left one below the umbo, the right one anterior to it. Animal insufficiently known. weak Shell longish, with 2 posterior bulges; less far forward, with fine concentric, Section Leguminaia strong, s. s. Shell fairly strong; sometimes with an accessory tooth mardinensis (Lea). Few species in the 832 umbo blunt, fairly high in Syria. — thin, with fairly thin, projecting; teeth left Near East and Pseudoleguminaia Germain, 1911. Shell elliptical; umbo in the valve. Tripoli. L. — somehwat (L.) Section inflated, close to the center, with irregular wrinkles; teeth very and thick. L. (P.) chantrei (Locard) = locardi Simpson, Section Microcondylaea Vest, 1866. Shell compressed, fairly low umbones; teeth rudimentary, greatly compressed. L. (M.) uniopsis (Lamarck), in the Po region and Illyria. 1267 Anodonta Lamarck, 1799 Shell thin, inflated, umbo more or less elongated, often posteriorly angulate; with several parallel, often somewhat biseriate wrinkles; lateral surfaces in most cases smooth; hinge margin weak, toothless. Several species in North and Central America, in Asia, and Europe. A to few subgroups, which were proposed by various zoologists, seem have justification. little Simpson considers Colletopterum Bourguignat, 1881 (letourneuxi Bourguignat) in the Danube, identical with Anodonta s. s.; 1933, erected a section Euphrata for A. bahlikiana, and Pallary, Bede, 1932, a group Liouvillea for the Moroccan A. pallaryi, Gabillotia Servain, China, in Syria to Asia Minor, and 1886 [magnifica (Lea) = woodiana (Lea)], in 1890 [pseudodopsis (Locard)], Pteranodon may P. Fischer, perhaps have the rank of section, but the Swainson, be called Patularia 1840; Haasiella must perhaps Lindholm, 1925 latter is said to differ by the hook-less glochidia. few groups have been erected for American species, such as Brachyanodon Crosse & P. Fischer, 1893, for chapalensis Crosse & P. Fischer, Mesanodon Crosse & P. Fischer for lurulenta Morelet, and Pyganodon Crosse & P. Fischer, 1893, for globosa Lea; Arnoldina Hannibal, 1912 (dejecta Lewis), has non-elevated umbones with tubercles and few biseriate wrinkles, alternating with punctures on the posterior bulge and Nayadina Gregorio, 1914 (venusta Gregorio), has a small process on the posterior part of the hinge margin in the left (only known) valve. Lastena Rafinesque, 1820 (ohiensis Rafinesque) = Vtterbackia (arcaeformis Heude, in China) A F.C. Baker, 1927, is Bourguignat, 1877, Utterbackiana Frierson, said to be hermaphroditic; 1927 (orbiculata Say), is said to be non-hermaphroditic. Pseudanodonta considered as a genus by Haas, has not been recognized even as a section by Ortmann. Strophitus Rafinesque, 1820 Synonym Hemiodon = Hemidonta Swainson, Shell fairly strong, inflated, posteriorly with edge; umbo elevated, 1 1840. or 2 corners and a flat with few strong, posteriorly sharply upcurved concentric wrinkles; in each valve with a rudimentary compressed tooth and sometimes an accessory tooth; lamellae seldom present. The marsupium, which occupies the entire outer gills, consists of short, horizontal, transversely oriented S. undulatus (Say). Frierson Few egg pouches. species in the United States. recognizes Jugosus Simpson (wrightianus Walker) and Pseudodontideus Frierson, 1927 [alabamensis (Lea)], as subgroups. 1268 ? Solenaia Conrad, 1868 Shell fairly thin, greatly elongated, anterior part shorter and lower than the posterior, an edge runs to the posterior corner; both ends gaping; umbo low, with concentric, indistinctly biseriate wrinkles; indications of one or more Foot very strong; gills S. all emarginata (Lea). hinge with lamellae; mantle line with a posterior sinus. with egg sacks. Few species in China and Indochina. C. Subfamily Lampsilinae 833 Shell roundish or longish; umbonal sculpture in most cases biseriate, often indistinct, seldom concentric; hinge teeth as a rule well developed, occasionally the sexes are different. Supraanal mantle opening separate, seldom completely closed; mantle margin anterior cases formed of the posterior part to the gill opening marsupium in most of the outer gill lamina, which is smooth or folded or with peculiar papillae or a usually folded during the gravid state; lobe; water tubes simple; glochidia without hooks or with 2 thorns. Frierson placed the first 4 genera in the Unioninae. In North and Central America. Ptychobranchus Simpson, 1900 Shell strong, longish triangular; biseriate umbo elevated, with weak, wrinkles; posterior edge rounded; somewhat hinge margin fairly broad; anterior teeth small, low, triangular, rough; lamellae club-shaped. Supraanal opening long, separated from the anal opening by a narrow bridge; marsupium formed by folds; greater part of the outer gill lamina, with 6-20 egg sacks continuing below into a roundish swelling, which has a colored patch in the center. P. in the phaseolus (Hildreth) [= fasciolaris (Rafinesque) ?]. Few species United States. Frierson, 1927, proposed a group Subtentus for P. subtentus (Say). Obliquaria Rafinesque, 1820 Shell especially anteriorly strong, inflated, only slightly elongated, with a bulge at the posterior large warts alternating corner and a straight descending on the two valves; umbo projecting, with row of 4 or 5 coarse wrinkles, which are posteriorly upwardly curved; anterior teeth strong; lamellae short. Marsupium consisting of 4—7 distinctly different 1269 egg sacks, which lie and are elongated; somewhat behind their the center of the outer gill lamina, ends are rounded. O. reflexa Rafinesque, in the United States. Conchodromus Haas, 1930 Synonym Dromus Simpson, Shell 1900, non Selby, 1840. rounded triangular; umbo especially strong anteriorly, fairly row of tubercles runs down over the center of the sides; hinge margin broad and flat; main teeth triangular, small and low; lamellae short, club-shaped. The marsupium occupies the greater part of the outer gill lamina and forms numerous high, with fine concentric wrinkles, a narrow, elongated egg sacks. dromas C. (Lea), in the United States. Cyprogenia L. Agassiz, 1852 Shell strong, inflated, rounded triangular; weak, somewhat biseriate wrinkles; lateral umbo elevated, with very surfaces tuberculate; hinge main teeth strong, blunt, triangular; lamellae short, transversely striated. The marsupiums formed of 7—23 very long, red egg tubes, which are together spirally inrolled; supraanal opening margin broad and long, separated flat; from the anal opening by a narrow bridge. irrorata (Lea) [= stegaria (Rafinesque) ?] in the United States. C. Plagiolopsis nom. nov. 834 Shell strong, longish triangular, posteriorly female, with posterior edge, concentrically striated; parallel, shaped. gill more umbo inflated in the high, with fine somewhat biseriate wrinkles; hinge teeth rough; lamellae clubThe marsupium is formed of a part of the posterior half of outer lamina, and consists of distinctly different, ventrally rounded egg sacks. P. securis (Lea), in the United States. Whereas Herrmannsen, 1847, named Unio interruptus Rafinesque as the genotype of Plagiola, Simpson accepted U. lineolata Say = securis Lea as such. On the other hand, according to Herrmannsen, the genotype of Truncilla is U. truncatus Rafinesque, a species considered synonymous elegans Lea and placed by Simpson and Ortmann in Amygdalonaias, while Agassiz also considers it as a Plagiola species. with U. Therefore, these generic names have opinions vary with respect to to be changed, but unfortunately, Unio interruptus; otherwise considered 1270 identical with U. brevidens Lea, Frierson considers menkianus Lea, which according correct, then to him belongs synonymous with it U. to Lampsilis; if this is would Plagiola = Lampsilis. Truncilla Rafinesque, 1820 Synonym Amygdalonaias Crosse & P. Fischer, 1893. Shell inflated, posteriorly obliquely truncate, with distinct edge to the posterior corner; umbo somewhat projecting, with margin narrow; main teeth biseriate sculpture; hinge somewhat fine, compressed, fairly high and rough. Marsupium consisting of numerous egg sacks, with a distinct T. furrow some distance above their base. truncata Rafinesque. A couple of species in Mexico and the United States. Medionidus Simpson, 1900 Shell fairly inflated, longish, wrinkled in the upper the posterior part; umbo and sometimes only slightly projecting, with fairly fine, often somewhat somewhat swollen. The interrupted, biseriate wrinkles; anterior hinge teeth small, blunt, rough; lamellae fairly short; females posteriorly marsupium occupies a more or consists of less large part fairly large, irregular A M. conradicus (Lea). of the outer few species in the lamina and gill egg sacks which are rounded at the ends. United States. Glebula Conrad, 1853 Shell strong, posteriorly obliquely truncated, short, posterior edge, posteriorly umbo compressed; more with a low inflated in the female than in the male; anterior hinge teeth divided into several irregular parts, forming a granulose lamella; hinge margin very weak; lamellae short; egg sacks G. distinctly separated from one another by a furrow. rotundata (Lamarck), in the United States. Proptera Rafinesque, 1819 , Synonyms Metaptera Rafinesque, 1820; Symphynota Lea, 1829; Naidea Swainson, 1840. Shell anteriorly 835 in most cases large, differently somewhat gaping, with a sculpture, with a posterior teeth often rudimentary. formed dorsal wing; in the umbo two sexes, with weak and sometimes also an anterior row; hinge consists of several egg sacks The marsupium which occupy the posterior part of the outer gill lamina; supraanal 1271 opening long; posterior part of the lower mantle margin somewhat folded on either side with 2 thorns on the ventral margin. in the female; glochidia P. alata (Say), in the United States. Leptodea Rafinesque, 1820 Synonyms Lasmonos Rafinesque, 1831; Paraptera Ortmann, 1911. Shell large and thin, more or less compressed, dorsally winged; umbo low; hinge teeth compressed, weak and often incomplete; sexes scarcely differing. Mantle and marsupium similar to those in Proptera. Glochidia very small, oval. L. fragilis Rafinesque, in the United States. Obovaria Rafinesque, 1819 Shell strong, roundish to oval, inflated, anteriorly thickened, differently formed in the two sexes; umbo high, with tuberculate wrinkles; club-shaped. irregular, fine, anterior hinge teeth strong, blunt; Marsupium somewhat lamellae short, consisting of several elongated egg sacks in the posterior part of the outer gill lamina; supraanal opening fairly long, separated from the anal opening by a very short bridge. Few species, in the United States. Subgenus Obovaria in s. s. Shell roundish, with high Subgenus Pseudoon Simpson, 1900. Shell anterior end; ellipsis marsupium situated situated somewhat & Shell longish, fairly compressed; few weak wrinkles; sexes only several, oval; farther umbo close to the forward. O. (P.) (Lea). Actinonaias Crosse gill umbones the center O. (O.) retusa (Lamarck). P. umbo Fischer, closer to the anterior end, with slightly different. somewhat elongated egg sacks 1893 Marsupium formed of in the posterior part of the outer lamina. A. sapotalensis (Lea). A few species, in Mexico and the United States. Graphonaias Crosse & P. Fischer, 1893 [medellina (Lea)], not separable. Toxelasma Rafinesque, 1831 (Toxolasma) Synonym Carunculina Simpson, 1898. is probably 1272 Shell small, fairly strong, inflated, longish; umbo situated anterior to with fairly strong concentric wrinkles which are strongly the center, in most somewhat different. Marsupium consisting somewhat elongated egg sacks; the mantle in the upwardly curved posteriorly; anterior hinge teeth compressed, cases upwardly curved; sexes of few fairly large, female has a lobe anterior to the incurrent opening. T. A lividum (Rafinesque). few species, in the United States. Ligumia Swainson, 1840 Shell more or elongated, less biseriate; the posterior part or swollen. 836 smooth; umbonal sculpture fine, of the shell in the female somewhat widened Marsupium occupying the posterior part of the outer gill lamina; posterior half of the ventral mantle margin in the female with distinct papillae; A supraanal opening fairly long. few species in the United States. Subgenus Ligumia s. Shell long, posteriorly s. more or less pointed; papillae at the mantle margin identical, extending to the center. L. (L.) (Lamarck). recta Subgenus Micromya L. Agassiz, 1852. Shell slightly pointed; of the margin oval, posteriorly only mantle papillae dissimilar, not extending to the center L. (M.) fabalis (Lea). Friersonia Ortmann, 1912 Shell fairly small, longish; umbonal sculpture biseriate, with 6-8 fine wrinkles; sides smooth; sexes scarcely different. The marsupium occupies the greater part of the outer gill lamina; it consists of numerous elongated egg sacks with their ends posteriorly curved; the margin is sharp; posterior part of the ventral mantle margin finely folded. P. iridella (Pilsbry & Frierson), in Mexico. Lampsilis Rafinesque, 1820 Synonym Aeglia Swainson, Shell more or less longish, 1840. smooth or concentrically close to the center, with parallel wrinkles; right valve with teeth is and a lamella, the left striated; 1 umbo or 2 anterior one with 2 teeth and 2 lamellae; the shell The marsupium occupies lamina and consists of numerous egg posteriorly distinctly truncated in the female. the posterior part of the outer gill sacks; in the female the posterior part of the ventral mantle margin forms a rib-shaped lobe (Fig. 808). 1273 Fig. aa, ap, anterior lamina; lobes; 1, s, 808. Female of Lampsilis ovata (Say), and posterior adductor muscle; f, foot; k, k,, inner and outer gill posterior ventral lobe of the mantle margin; m, marsupium; p, oral s,, incurrent and excurrent opening; sa, supraanal opening of the mantle (after Ortmann). ovata (Say). Several species, in Central America and the United L. States. The following groups proposed by Crosse & P. Fischer, 1893, are considered as sections: Cyrtonaias for Unio berlandieri Lea (shell thick, somewhat quadrangular, smooth or concentrically striated; umbo in most cases), Mesonaias for U. explicatus Morelet (shell elongated oval, smooth or concentrically striated; umbo only slightly oval or inflated elevated; anterior hinge U. discus Lea concentrically striated; U. 837 teeth oblique, (shell large, oval or paludosus Morelet anterior hinge (shell compressed), Disconaias for somewhat flattened, triangular, greatly flattened, teeth strong), posteriorly with Phyllonaias for a weak dorsal wing; anterior hinge teeth in most cases compressed), and Delphinonaias for V. delphinulus Morelet (shell greatly flattened, posterior to the umbones with 1927, a large wing; hinge teeth compressed). Moreover, Frierson, named Ortmanniana villosa (Wright), for L. carinata (Barnes), Villosa for L. Venustaconcha (= Venusta Frierson non O. Boettger, 1877) for L. venusta (Lea). 1274 & Pachynaias Crosse P. Fischer, 1893 Synonyms Arotonaias Martens, 1900; Ptychoderma Simpson, 1900. Shell rounded or triangular, strong, strongly concentrically striated; umbo projecting, fairly with fine, discontinuous wrinkles; irregular, hinge margin narrow; anterior teeth compressed, rough; lamellae short, obliquely striated. Gills small; the marsupium occupies the posterior part of the outer lamina and forms rounded 1—20 separate egg sacks which are with a furrow near the base; mantle margin ends, the at 1 thickened and doubled, sometimes folded. spheniopsis (Morelet). P. A few species, in Central America. Lemiox Rafinesque, 1831 Synonym Conradilla Ortmann, 1921. more or less inflated, somewhat longish; umbo high, sculpture, on the posterior part of the shell with strong Shell strong, with biseriate radial wrinkles; hinge teeth low, rough, 2 in the valve; lamellae double on the sexes different; left, left 1-3 in the right some of them double on the right; females smaller than males; mantle margin exteriorly few small denticulate anterior to the incurrent opening; interiorly with a papillae and then elevated, thin, probably extensible. caelatus (Conrad), in the United States. L. Epioblasma Rafinesque, 1831 Shell strong, inflated, roundish, oval or triangular, differing in the two sexes, in most cases smooth; umbo projecting, weakly sculptured. In the posterior part of the mantle margin, the inner and outer margins in the female are margin is more or from one another and the inner marsupium consisting of many egg sacks less separated beset with papillae; and occupying the posterior part of the outer A few gill lamina. species, in the United States. Section Truncillopsis Ortmann & Walker, 1922. smooth; male without posterior furrow; female inflated edge. E. {T.) triquetrum (Rafinesque). — Section Epioblasma oval, in the in the s. s. (synonym Dysnomia male with a broad, shallow longish, Section Pilea Simpson, Shell oval; female with a rounded radial bulge. E. (P.) — Shell at the posterior radial 1900. personatum (Say). L. Agassiz, 1852). Shell furrow behind the center, female with a bulge passing into a large lobe. E. (E.) bilobum (Rafinesque) = foliation (Hildreth). names: Penita for E. In addition, Frierson, 1927, also penitum (Conrad), Torulosa for E. torulosum 1275 Ortmann and (Rafinesque), and Capsaeformis for E. capsaeforme (Lea). Walker, 1922, erected a subgenus Scalenilla for "Unio" sulcatus Lea. Family 3. Shell variably formed; umbo MUTELIDAE with radial sculpture or without sculpture. Incurrent and excurrent openings separated is sometimes short, by a mantle bridge, the latter sometimes long, but a supraanal opening separated, the attachment of the inner gill is not lamina extends to the oral sometimes have no water tubes; interlamellar junctions lobes; the gills marsupium only scattered or forming perforated or solid septa; in the inner lamina; occasionally the mantle margins are fused anterior to the incurrent opening. A. Subfamily Hyriinae umbonal Shell with hinge teeth and radial of the anal mantle opening developed in closed; sculpture; the upper part interlamellar junctions of the female and in in the outer gills marsupium in the is weakly those of the male, all most cases forming a discontinuous network, often arranged in rows, so that incomplete septa, rarely solid septa and separate water tubes, are formed; often the marsupium occupies only a part of the inner gill lamina; the innermost lamella larvae are glochidia, in simple, long and thin, curved thorn In is completely attached; the most cases with a ventral corner, on which a often attached. is South America and Australia. Hyridella Swainson, 1840 Synonym Microdontia Tapparone umbo Canefri, 1883. most cases tuberculate wrinkles, which below approach one another; sides in most cases furrowed; hinge teeth fairly weak, compressed, sometimes somewhat rudimentary. Anal opening small, roundish, with expanded margin; a Shell oval; small opening is low, with curved, in present between the posterior end of the gill and the mantle bridge. A few species, Section in Australia, Protohyridella New Cotton Guinea, and & Gabriel, somewhat rhomboidal, with an edge from New 1932. Zealand. Shell strong, umbones to the posterior corner, dividing the surface into an anterior wrinkled and a posterior smooth part; umbo the not projecting; hinge teeth well developed. H. (P.) glenelgensis (Dennant). — Section Propehyridella Cotton & Gabriel, 1276 1932. Shell similar to Hyridella australis, strong, irregularly wrinkled on the umbones, thereafter smooth; nepeanensis (Conrad). H. (//.) — hinge teeth well developed. H. (P.) Section Hyridella s. Umbo s. without sculpture. australis (Lamarck). Diplodon Spix, 1827 Shell roundish to elongated oval; more or slightly elevated, with umbo closer to the anterior end, only less distinct radial sculpture; a posterior edge not or weakly developed; hinge teeth smooth or rough, but not The transversely furrowed. sometimes scattered network or solid interlamellar junctions in the gills variable, small numbers, sometimes joined to form a in septa. Several species in South America. Subgenus Diplodon s. s. (synonyms Iridea Swainson, 1840; Niaea (Swainson) Morch, 1853). Shell longish; D. (D.) ellipticus (J. A. Wagner) umbo with continuous ridges. = wagnerianus Simpson. Subgenus Rhipidodonta Morch, 1853 (synonym Cyclomya Simpson, umbo 1900). Shell roundly oval; sculpture; hinge anteriorly inclined, with irregular radial margin arched, lower main tooth of the right valve often divided into small denticles; the teeth of the D. (/?.) left valve are also denticulate. paranensis (Lea). Subgenus Bulloideus Simpson, 1900. Shell 839 with posterior edge; umbo compressed, somewhat divided, 2 on the on the right, 2 on the inflated, roundish, thin, with regular radial ridges; hinge teeth elongated, right, 1 on the left; 1 lamella D. (B.) bulloides (Lea) = variabilis (Maton). left. Castalina Jhering, 1891 Shell somewhat triangular, laterally flattened, with edge and a weak wing; umbo moderate posterior elevated, with radial sculpture; hinge teeth smooth, pleated, or with parallel furrows. Interlamellar junctions of the gills scattered. C. martensi Jhering. A few species, in Brazil. Castalia Lamarck, 1819 Synonym Tetraplodon Shell strong, Spix, triangular, 1827. with distinct posterior edge; umbo high, with distinct sculpture extending over a large part of the shell; hinge margin curved, on the left with a very strong, compressed tooth, and on the right with 2 teeth anterior to the umbones, posterior to these with a few small denticles; on the right with 1, on the left with 2 transversely 1277 grooved lamellae; mantle margins below the incurrent opening most in cases fused with one another. ambigua Lamarck C. (Fig. 809). A few species, in South America. v 809. Inner side of the right shell valve of Castalia undosa Martens. Fig. Castaliella Simpson, 1900 Shell fairly strong, triangular, with sharp posterior edge and strong concentric umbo sculpture; margin narrow, curved; high, with regular radial right valve with 2 furrowed main sculpture; teeth, the hinge lower valve with 3 main teeth, the median of of which is which the largest; posterior to the teeth with a few minute warts; a is larger and cleft; left granulose lamella in the right valve, 2 indistinctly transversely striated ones in the C. left valve; nacre purplish. Animal unknown. sulcata (Krauss), in Surinam. Callonaia Simpson, 1900 Shell thin, inflated, triangular, with sharp posterior edge and high umbones, without sculpture; hinge margin strongly curved, on either side with 2 high and compressed main teeth; on the left with 2, on the right which are somewhat granulose transversely striated. Animal unknown. with 1 C. lamella, duprei (Recluz), in Brazil. Prisodon Schumacher, 1817 Shell anterior somewhat triangular or rhomboidal, in most cases with small and larger posterior wing. Interlamellar junctions of the gills 1278 more densely-spaced and forming net-like interrupted septa in median part of the inner lamina; mantle open below. A few species, in Guyana and the Amazon River. Subgenus Triplodon Spix, 1827 (synonyms Naia Swainson, 1840; Harmandia Rochebrune, 1881). Umbo with strong radial sculpture; scattered, the marsupium, which occupies the 840 posterior edge moderate. scarcely developed; teeth; — 2 lamellae on the Section Triplodon Section s. s. left, one on the Wings Simpson, Triquetrana right. P. (T.) stevensi (Lea). distinctly developed, 2 or more short, compressed and cleft main Wings 1900. each valve with 3 main sculpture very extensive; on either side with teeth. P. (T.) rugosus Spix. (synonyms Triquetra Klein, 1753;? Paxyodon Schumacher, 1817; Hyria Lamarck, 1819, Hyriana Simpson, 1900). Umbo without sculpture; posterior edge sharp. P. (P.) obliquus Subgenus Prisodon s. s. Schumacher. The genotype of Hyria designated by Herrmannsen is Mya syrmatophora Meuschen, which has also been considered as the genotype of Prisodon by Simpson; therefore the two names are synonymous. B. Subfamily Mutelinae variably formed, without distinct Shell teeth umbonal sculpture; hinge incomplete, always without lamellae, or completely absent, or replaced by a series of tubercles. Anal opening of the mantle in most cases widened above; gills with septa and water tubes; in the the septa are more strongly developed and have a marsupium longitudinal ridge on the outer lamella; in the gravid condition only the inner part of the water tubes is somewhat widened and filled with eggs, its outer part forms secondary water tubes; larvae of most genera unknown, in Anodontites they are very different from glochidia, the anterior pear-shaped part ciliated, the with a few are known median bears a stiff bristles; thin small shell, and the posterior is is cleft, they produce a broad thin secretory band; they as lasidia. In Africa, South and Central America. Haasica Strand, 1932 Synonym Marshalliella Haas, 1931, non Kieffer, 1913, nee Poppius, 1914. Shell fairly small, roundly oval, inflated, plate on the on a well-developed hinge right is a high, narrow, oblique tooth, behind which bordered posteriorly by a narrow denticle; on the left is a pit with a callous 1279 thickening and posterior to a deep, narrow groove somewhat hooklike, curved is a high, slender, tooth. H. balzani (Jhering), in southern Brazil. Diplodontites Marshall, 1922 Shell umbo moderately elongated oval; elevated; with radial furrows and microscopic granulose teeth, the anteriormost of which is valve with 3 the strongest, high, and triangular; left valve also with 3 teeth, the anteriormost of which median sculptured sides striae; right is weak, whereas the very strong and triangular. is D. cookei Marshall, from the Rio Colorado, tributary of the Magdalena River, in Colombia and from Huancabamba the Rio Peru. in Tamsiella Haas, 1931 Shell elongated oval; right valve with a low, blunt tooth, not lie on a hinge margin, and behind 841 tubercle below the it a shallow umbo, which does but represents a receded part of the dorsal ridge, pit; left valve with a anterior and posterior to weak dentiform with a shallow it pit. tamsiana (Dunker), from a tributary of the Orinoko. T. Jheringella Pilsbry, 1893 Synonym Plagiodon Lea, 1856, non Dumeril, 1853. Shell small and thick, inflated, anteriorly and posteriorly truncated; umbo high; left valve with an irregular tooth below the umbo; right valve with 2 teeth. J. isocardioides (Lea). A couple of species, in Rio la Plata and in Peru. Monocondylaea Orbigny, 1835 Synonyms Aplodon Pilsbry, Spix, 1827, non Rafinesque, 1818; Spixoconcha 1893. Shell fairly strong, roundish to oval, with either side with left one hinge one situated anterior tooth, which in the right, to weak most cases posterior edge, on is compressed, the sometimes with indications of accessory teeth; surface in most cases with somewhat lamellose concentric striae. Anal mantle opening wide; are alternately stronger and gills with well-developed septa, which weaker; in the marsupium they are more regular and stronger. M. paraguayana Orbigny. South America. A few species, in the eastern parts of 1280 Fossula Lea, 1870 weak edge and Shell strong, inflated, oval, with fairly high umbones; which clasp the single one of the right valve with 2 teeth, left valve, sometimes with indications of accessory teeth; hinge margin narrow. Animal similar Monocondylaea. to that in (Orbigny), in Brazil. F. fossiculifera Anodontites Bruguiere, 1792 Synonyms Patulaha Swainson, 1840; Glabaris Gray, ? Styganodon Martens, Shell or oval somewhat trapezoidal, sometimes somewhat gaping; hinge teeth absent. Anal mantle opening lunule anteriorly prolonged; wide; mantle completely open below; foot moderately large; The well developed. 1847; 1900. larva gill septa a lasidium. is Several species, in South America east of Cordillera and in Central America to Mexico. Section Anodontites s. more or Shell s. less longish, but not greatly elongated or posteriorly pointed, without sharp posterior edge. A. (A.) crispata Bruguiere. 1893, are also to 1840 (synonym Euryanodon and Pseudoleila Crosse & P. Fischer, Section Lamproscapha Swainson, be placed here. Virgula — Simpson, 1900). Shell greatly elongated and posteriorly pointed, with sharp posterior edge. A. (L.) ensiformis (Spix). — Section Ruganodontites Marshall, somewhat indented 1931. Shell moderately long, often ventrally; surface with fine, irregular radial wrinkles. A. (R.) colombiensis Marshall. Leila Gray, 1840 Synonym Columba Lea, 1833, non Linne, 1758. Shell large, inflated, anteriorly somewhat oval; hinge margin straight, toothless, and posteriorly somewhat produced wing-shaped, gaping. The mantle line forms a sinus posteriorly; mantle margins fused anterior to the incurrent opening. L. esula (Orbigny). Few species, in South America. Mycetopoda Orbigny, 1835 842 Synonym Mycetopus Orbigny, Shell thin, truncated, with elongated, 1847. anteriorly gaping, posteriorly obliquely low posterior edge and low umbones; hinge margin long, 1281 straight, Foot very long, swollen toothless. opening closed upper the in part; gills the at very long; end; anal mantle innermost lamella completely attached. A M. siliquosa (Spix). few species, in South America. Mycetopodella Marshall, 1927 Shell greatly elongated, anteriorly very low; anterior end; a broad umbones close to the running from them to the lower constriction margin, posterior to which the shell gradually broadens to the obliquely truncated posterior end; the umbones straight, posterior edge sharp; hinge margin behind obliquely descending anterior to the toothless, umbones. M. falcata (Higgins), South America (Amazon River). in Aspatharia Bourguignat, 1885 Shell more or less elongated oval; hinge margin toothless, posteriorly abruptly or obliquely delimited by a deep triangular sinus, sometimes with a low blunt, tooth-like projection below the umbo of the left valve. Mantle completely open below or with a short fusion anterior to the incurrent opening; anal opening short; innermost A few species, Subgenus Aspatharia shell longish, s. gill lamella not attached. Africa to Egypt. in tropical s. Umbo with obtusely angled wrinkles; moderately bulging, smooth or with warty wrinkles; mantle completely open below. A. (A.) vignouana (Bernardi). Subgenus Spathopsis Bourguignat, 1885 (non J. Simpson, Hall, 1900 (synonyms Spathella 1885); Leptospatha Germain, 1904; Mitriodon Rochebrune, 1904). Umbo Rochebrune & with short concentric wrinkles; shell oval or longish, moderately bulging, smooth or with a few wrinkles in the posterior part; lunule very narrow; mantle margins with a very short fusion anterior to the incurrent opening. A. (S.) guillaini (Recluz). Arthropteron Rochebrune, said to differ by the broader 1905 (puassouloui Rochebrune), lunule, is and Moncetia Bourguignat, 1885 = lavigeriana Bourguignat), by its strongly compressed form. Subgenus Brazzaea Bourguignat, 1885. Shell thin, oval, greatly inflated; the dorsal margin of the left valve anterior to the umbones {anceyi slightly surpassing that of the right valve. A. (B.) anceyi (Bourguignat). Pseudospatha Simpson, 1900 Synonym Burtonia Bourguignat, 1883, non Bonaparte, 1850. 1282 Shell thin, smooth, strongly compressed, somewhat winged; umbo wavy and warty; low, in about the anterior quarter, nearly smooth or hinge margin straight, toothless, with an angular or narrowly elevated, and posteriorly diverging edge. anteriorly P. tanganyicensis (Edg. Smith). Few species, in Lake Tanganyika. Mutela Scopoli, 1777 Synonyms Spatha Lea, 1838; Calliscapha Swainson, 1840; Mutelina Bourguignat, Shell 843 by a 1885; Pseudomutela Simpson, more or less elongated; 1900. hinge margin posteriorly not delimited sinus, narrow, toothless or with weak, A few species, in tropical Africa Section Mutela s. and to a greater extent. in the Nile. Shell without keels or wings s. M. (M) dubia (Gmelin). edge. short denticles, especially umbones; mantle closed below anterior to the — on the posterior Chelidonopsis Ancey, Section 1887 (synonym Chelidonura Rochebrune, 1886, non A. Adams, 1850). Shell with keels or wings on the posterior edges. M. (C.) hirundo (Martens). Iridina Lamarck, Synonyms Platiris Lea, 1819 1838; Eufira Gistel, 1848. Shell oval or longish; hinge margin with a mantle teeth; fairly widely closed below; gill row of tubercle-shaped laminae fairly equally broad. A few species, in tropical Africa. s. s. Shell longish; hinge margin with many small and a low projection below the umbo of the left valve. /. (/.) exotica Lamarck. Section Cameronia Bourguignat, 1879. Shell longish; Section Iridina denticles — hinge margin narrowed below the umbones, with strong, irregular teeth which are weaker anterior — to the umbones /. (C.) spekii S.P. Woodward. Section Pliodon Conrad, 1834 (Pleiodon). Shell oval; hinge with strong teeth anterior and posterior to the umbones. /. (P.) ovata Swainson (Fig. 810). 4. Shell Family irregularly formed, AETHERIIDAE often with one valve cemented to the The very wide anal opening separated from the incurrent opening by a mantle bridge; the innermost gill substratum, without hinge teeth. lamellae anteriorly fused with the visceral sack, posteriorly fused with one another; the gill laminae smooth in Acostaea, in Aetheria they have 1283 Fig. 810. Inner side of the right shell valve of Iridina {Pliodon) ovata Swainson. Length 10.5 cm. numerous small folds; the two lamellae of each lamina are joined with one another by some complete, some incomplete, septa running to parallel the filaments; those in the inner laminae are considerably stronger than in the outer ones, between them very small eggs were found (only in the inner lamina ?); embryos unknown; a foot absent; the ventricle not traversed by the intestine, but lies below muscle is is the anterior adductor sometimes reduced. Bartlettia H. Shell solid-walled, 844 it; more or Adams, 1866 less elongated, often with a ventral sinus, anteriorly narrowed; umbo rough growth posterior to the strong ligament with a triangular sinus; adductor lines; scarcely projecting; outer side with irregular, muscle scars far removed from one another, the one narrow. One of the valves appears attached. B. to anterior be only slightly or not at all Animal unknown. stefanensis (Moricand), in the Amazon River. Aetheria Lamarck, 1807 (Etheria) cemented by one valve, which Shell irregularly formed, inequivalve, is sometimes greatly thickened and has a lighter structure; posterior to the ligament with a deep, narrow sinus; both adductor muscles present. Mantle margins with papillae A. elliptica Lamarck, in all around. tropical northwestern part of Madagascar. Africa, in the Nile, and the 1284 Acostaea Orbigny, 1851 Synonym Mulleria far forward; Ferussac, 1823, non Leach, 1814. cemented by one valve, solid-walled; umbo lying Shell inequivalve, posterior to the ligament with a sinus; anterior adductor muscle reduced. Along the posterior part of the mantle margin with a row of papillae. Subgenus Acostaea s. s. (synonym Eumulleria Anthony, 1907). with a thin anterior process, which encloses the embryonic shell. Shell A. (A.). (Deshayes), in the Magdalena River (South America). rivolii Subgenus Pseudomulleria Anthony, 1907. Shell without conspicuous anterior process. A. (P.) dalyi (Edg. Smith), in India. HETERODONTA Suborder In most cases well-developed hinge plate bears few main teeth, of which the right central tooth interlocking alternating is and occasionally reduced, and often anterior and posterior lateral teeth; ligament in most cases external, more or more seldom sunken between the hinge teeth. Siphons less developed. I. Shell small or of STIRPS ASTARTACEA medium size, in most cases strong and roundish somewhat elongated, often with concentric sculpture; hinge margin broad, in most cases on the right with one central tooth, which is clasped by 2 teeth of the left valve; in addition there may be fairly distinct indications of outer main teeth or lateral teeth; adductor muscle triangular or scars distinct; mantle line without sinus. Mantle anal siphon; visceral sack gill open except for a short laminae of unequal breadth, without fusions with the and the mantle, as a rule smooth, with regular interfilamentar junctions in the lamellae and scattered interlamellar junctions; proximal limb of the kidney short and fairly wide; distal limb sack-shaped, with a few rather strong lobes, united with one another above the ciliated funnels. Marine. 1. Shell angulate above, Family ASTARTIDAE rounded below, fairly strong, externally smooth or in most cases concentric sculpture; ligament external; central tooth of the right valve strong, occasionally with a main tooth; left valve with 2 strong main weak teeth anterior or posterior and sometimes with a 1285 845 posterior tooth below the ligament; lateral teeth variable, situated at the margin, in most cases rudimentary; sometimes the dentition of the two sides is reversed. Astarte J. Synonym Crassina Lamarck, Sowerby, 1816 1818. Characters of the family. Several species, mainly in the cold Nordic seas. Section Astarte s. Inner margin of the shell denticulate, externally s. concentrically sculptured. A. (A.) sulcata (da Costa). Schumacher, 1817. Inner margin smooth. A. Schumacher] (Fig. 811). Nicania Leach, smaller size. A. (A.) banksi Leach. — small, externally with furrows, Shell (T.) 1819, J. Sowerby. Martens, 1874). — Section Tridonta is Section Gonilia Stoliczka, = — in 1871. the center; bipartita (Philippi) Section Rictocyma Dall, 1872 (synonym Rhectocyma Shell externally with concentric, discontinuous and sometimes bifurcated wrinkles; inner margin smooth. A. Baird. [(Chemnitz) separated only by which form angles inner margin denticulate. A. (G.) calliglypta Dall non — borealis Section Digitaria S. (R.) esquimalti Wood, 1853 (synonym Woodia Deshayes, 1860). Shell with curved furrows, which obliquely cut the growth lines; inner margin denticlulate. A. Fig. 811. Fig. (£>.) digitaria (Linne) (Fig. 812). — Section Inner side of the right shell valve of Astarte arctica Gray. 812. Shell of Astarte (Digitaria) digitaria Linne, enlarged. 1286 Goodallia Turton, 1822 (synonym Mactrina T. Brown, 1827). Shell very smooth, interiorly denticulate, central tooth of the right valve small, interiorly indented; an anterior main tooth absent. A. (G.) triangularis (Montagu). Grant and Gale have referred to the the 2. variable Shell Family in beak-like, most cases strong, oval concentrically furrowed; often J. Sowerby as other as such. CRASSATELLIDAE in size, lurida Lamy and most = danmoniensis (Lamarck) malacologists consider A. sulcata somewhat fossil A. of the genus, whereas species typical or posteriorly umbo angular; ligament internal, situated posterior to the main teeth on the broad hinge margin; valve, valve with 2 teeth, which clasp the central tooth of the right left which a weaker tooth is more or less rudimentary; these anterior to posterior one grooved; is lateral also present, whereas a teeth are often transversely The animals teeth are scarcely developed. are in part similar to those in Astarte in part strikingly different in the structure of the of the gills foot. Crassatella Lamarck, (1799) 1801 Shell of small or medium size, in most cases longer than broad, oval or posteriorly truncated or beaked, besides the main teeth distinctly developed in the left valve, lateral teeth are 2 anterior and Several species, mainly in 846 1 formed, 1 more or less anterior and 2 posterior posterior in the right valve. warm seas. Subgenus Crassinella Guppy, 1874 (synonyms Thetis C. B. Adams, 1845, non J. Sowerby, 1826; Pseuderiphyla P. Fischer, 1887). Shell small, greatly compressed, triangular; umbo pointed, situated almost in main teeth on either side; lateral teeth distinctly developed. Animal unknown. C. (C.) martinicensis Orbigny. Subgenus Crassatina Weinkauff, 1881. Shell more or less large; the center, 2 umbo angular, posterior part rounded or truncate or beaked; gill laminae smooth as in Astarte, but the margins of the ascending lamellae are fused outwardly with the mantle, interiorly in the posterior part with one another; the gill in female contains eggs; foot moderately large, with byssus. Section Crassatina s. s. Shell oval, fairly small, inner margin denticulate. C. (C.) divaricata (Chemnitz) to P. Fischer, Angas) 1887). is identical to = contraria (Gmelin) (according Talabrica Iredale, 1924 (C. aurora A. it; Salaputium Iredale, 1 924 Adams & (C. fulvida Angas), has 1287 on either side in the ligamental pit a small spoon-shaped process; arising from the main tooth and catching below margin smooth. strong. C. (E.) — that of the opposite valve; inner Section Eucrassatella Iredale, 1924. Shell large and kingicola (Lamarck). Subgenus Scambula Conrad, 1869. Shell posteriorly beaked; inner margin smooth; laminae distinctly folded, with well-developed main gill filaments; the interlamellar junctions are alternating high and low septa; foot very strong, suited for springing. C. (5.) supplana Conrad, fossil; the animal of C. floridana Dall was studied. Although Lamarck, Lamy 799, mentioned only an uncertain fossil species, 1 is no doubt that he meant Crassatella in the modern sense, probably corresponding with Crassatellites Kruger, 1823; it seems doubtful whether it is really identical with Eucrassatella but the according to latter is there probably to be considered only as a subgroup. Bemardina Shell very small, oval, with fine concentric furrows; embryonic hat-shaped; shell 1910 Dall, hinge margin with 2 right and 3 posterior to which the ligamental cartilage is left main margin of the right valve sunken into a shallow furrow of the and anterior left lateral tooth teeth, sunken; posterior dorsal left valve, clasped between 2 right lamellae; lower margin smooth. bakeri Dall, near the Coronado Islands (California). B. ? Shell Cuna Hedley, 1902 very small, triangular or roundish; nearly in the center, umbo angular, situated externally concentrically or radially sculptured; ligament internal; right valve with a strong triangular, below more or less cleft, central left tooth and an often rudimentary anterior and posterior tooth; valve with 2 main teeth; lateral teeth weak. Animal unknown. A few species, in Australia, Cuna New Zealand and South Africa. in most cases concentrically, sometimes radially sculptured. C. (C.) concentrica Hedley (Fig. 813). Section — Section curved; May. — s. Hamacuna s. Shell Cotton, triangular, 1931. Umbo hinge margin strong, compressed. Section Propecuna Cotton, 1931. hook-shaped downwardly C. (//.) hamata Hedley & Surface with furrows, which obliquely cut the growth lines, and with radial furrows. C. (P.) obliquissima Tate. 1288 ,^\ 846 Fig. 813. Exterior and interior sides of a shell valve of Cuna concentrica Hedley, enlarged. II. Shell STIRPS CAKDITACEA most cases with in radial ribs; anteriorly, correspondingly the posterior teeth in most cases reduced; ligament umbo more main or less shifted teeth are elongated; lateral as a rule external; mantle line nearly always without sinus. Foot in most cases with byssus. Marine. 1. Shell in Family CARDITIDAE most cases of medium size and strong, transversely oval or sometimes with greatly projecting umbones and therefore more triangular; the umbones in most cases lie anterior to the center and elongated, often shifted far forward, then the posterior adductor muscle becomes larger than the anterior; the ligament is as a rule external; the ventral margin denticulate; the main teeth of the hinge margin are almost always transversely grooved, 2 in the which is left, 3 in the right, but the anteriormost of often reduced; lateral teeth in gland present; most cases rudimentary. Byssal laminae smooth, the inner ones posteriorly fused with one another; mantle open except for the excurrent opening; the ventricle lies gill below the intestine; kidney similar to that in Astarte; development with brood care. Cardita Bruguiere, 1792 Shell strong, bulging, in umbones which most cases roundish or are close to the center; anterior main oval, with elevated teeth more or less 1289 reduced, as a rule without posterior lateral teeth; adductor muscle scars not greatly different. Several species in various seas. Venericardia Lamarck, Section umbones 1801. Shell oval, greatly diverging; the right central tooth surrounded valve, anterior and addition a small in anterior lateral teeth may be species. Vimentum species, C. posterior posterior — Edg. lateral of the on the tooth left right; fossil; also a couple of living Smith. — Section Pleuromeris Conrad, 1867. situated nearly in the center, projecting; anterior main tooth of the right the in valve weak; valve. left C. 1847; Actinobolus (Klein) Morch, and a small anterior and (P.) tridentata (Say). 1839 (synonyms Agaria Cardiocardita (Blainville) Anton, Section Gray, umbo teeth 1925, was erected for a small Australian Iredale, dilecta by 2 posterior tooth represented by small tubercles; mantle line without sinus. C. (V.) imbricata Lamarck, Shell small; with projecting, only slightly anterior to the center; hinge teeth not situated 1853; Azaria Tryon, 1872). Shell form similar to that in Venericardia; mantle line with a shallow posterior sinus; 2 left, main ajar (Adanson). Section Cardita — 3 right s. teeth; lateral teeth reduced. s. C. (C.) (synonyms Cardites Link, 1807; Arcinella Oken, 1815). Shell in most cases oval, with elevated umbones; anterior large, main tooth of the valve small, triangular; the posterior one left elongated; anterior main tooth of the right valve fused with the margin, the posterior one large and elongated; lateral teeth rudimentary. C. (C.) sulcata Bruguiere — Section = antiquata (Linne) (according to Children). 1867 (synonyms Arcturus Gray, Cyclocardia Conrad, non Cuvier, 1829; Scalaricardita Sacco, 1899). Shell roundish or colorless, with strong periostracum; umbo more or less high; hinge similar to those in Cardita s. s. — 1847, oval, teeth C. (C.) borealis Conrad. In cold seas. Section Pteromeris Conrad, 1862 (synonyms Coripia Gregorio, 1885; Triodonta Konen, 1893). Shell small, triangular; umbo pointed, anteriorly inclined; posterior side very short; right valve with a triangular, strong central tooth; lateral anterior teeth rudimentary; left valve with 2 teeth absent. C. (P.) perplana Conrad, mainly corbis Philippi; Miodontiscus Dall, fossil; few main teeth; living species, 1903 (synonym Miodon Carpenter, 1864, non Dumeril, 1859) seems to be scarcely different. C. (M.) prolongata (Carpenter). oval; ribs umbo — Section Bathycardita Iredale, 1924. Shell only slightly elevated, close to the anterior end; the broad bear short thorns. C. (B.) raouli Angas, near Australia. Megacardita Sacco, 1899. Shell forward; posterior main teeth fairly elongated oval; elongated; lateral umbo teeth — Section situated far rudimentary. (M.) jouanneti Basterot fossil; C. turgida Lamarck belongs here. C. 1290 Beguina (Bolten) Roding, 1798 Synonym Trapezium Mus. Shell posterior Calonn., 1797. more or less elongated, ribbed; umbo close to the anterior end; main teeth of the hinge margin long; lateral teeth sometimes reduced in adult shells; posterior adductor muscle scar larger than the anterior one. A few species in warm seas. Section Glans Megerle von Muhlfeld, 1811. Shell fairly small, quadrangular, with tuberculate or spiny ribs; anterior main tooth situated close to the shell margin; the posterior one moderately elongated; lateral teeth developed. B. (G.) trapezia (Linne). well (Blainville) L. Agassiz, posteriorly broadened; 1847; Jesonia Gray, umbo — Section Mytilicardita 1847]. Shell elongated, nearly terminal; ribs often scaly; anterior main teeth small, the posterior ones elongated; often a parallel tooth Section above that of the right valve. B. (M.) calyculata (Linne). Carditamera Conrad, 1838 (synonyms Lazaria Gray, 1854; Lazariella — Sacco, long, anteriorly lower than posteriorly; Shell 1899). terminal; a teeth distinctly reduced; lateral living species. folds, mainly teeth, lateral not in the posterior part; posterior — Shell large and strong, compressed, finely ribbed, to Modiolus; umbo main elongated, the anterior one of the right valve sometimes teeth well developed. B. (C.) arata (Conrad), fossil; few Section Beguina s. s. (synonym Azarella Gray, 1854). few strong left valve with 1, right with 2 umbo terminal, similar elongated posterior main teeth absent. B. (B.) semiorbiculata (Linne). Calyptogena Dall, 1891 Shell longish, weakly concentrically striated; umbo situated anterior to the center; posterior part gradually narrowed; periostracum strong; inner margin smooth; each valve has 2 main teeth and one anterior which become reduced in old shells. lateral tooth, Mantle margin finely fringed; siphonal openings warty; foot ovate cylinder-shaped. C. pacijica Dall, on the western coast of North America. Thecalia H. 849 & A. Adams, 1857 Shell similar to Mytilicardita, but in the female with a strong ventral infolding, which with the opposite one forms a space in which the embryos develop. T. concamerata (Chemnitz) (Fig. 814), near South Africa. . 1291 of the Fig. 814. Inner side right shell valve of Thecalia concamerata (Chemnitz). $ Length about 15 mm. Milneria Dall, 1881 Synonym Ceropsis Dall, 1871 (non Solier, 1839). umbones, from which a strong Shell small, with anteriorly situated edge runs to the posterior comer, delimiting the flattened lower side, thereupon with a few unequal radial ridges which are rough because of the growth lines; right valve with an elongated triangular tooth and a very small anterior and posterior denticle; main teeth left valve with 2 diverging and a posterior lateral tooth; in the female the ventral shell margin forms a hemispherical depression, which closed by the mantle is margin and receives the eggs, which develop within M. minima 2. Shell it. (Dall), near California. Family CONDYLOCARDIIDAE ribbed or more seldom smooth; small, ligament partly or completely internal; main teeth weak, sometimes scarcely separated from Animal unknown. the lateral teeth. Carditella Edg. Smith, 1881 Shell fairly small, ribbed, weak, partly in most cases oval; umbo angulate; internal; left valve with 2, the right with 3 but of which only the median is well developed; 1 ligament main anterior teeth, and 1 posterior lateral tooth on either side. C. pallida Edg. Smith. A few species mainly southern, seas. in various, Carditopsis Edg. Smith, 1881 Shell very small, ribbed or smooth; ligament completely internal, one tooth anterior to the ligament which are joined above; C. flabellum (Reeve). lateral Few on either side and 2 posterior teeth weak. species in various seas. to it, 1292 Condylocardia Bernard, 1896 very small, roundish or triangular, ribbed or concentrically Shell umbo striated; projecting, with distinctly delimited embryonic shell; ligament internal; the main teeth of the hinge are indistinctly separated from the 1 and somewhat lateral teeth posterior main different; on the left 1 anterior and on the right 2 connected anterior, and 1 posterior main tooth; 1 lateral tooth on either side. tooth; rudimentary triangular C. sanctipauli Bernard. A few species, mainly near Australia and in southern seas. Benthocardiella Powell, 1930 850 Shell similar to Condylocardia, roundish to triangular, smooth, with delimited embryonic shell; on the right with 2, on the left with 3 or 4 New Zealand and elongated main teeth; without lateral teeth. B. pusilla Powell (Fig. 815). A few species near the neighboring islands. Fig. 815. Hinge margins of the shell of Benthocardiella pusilla Powell, enlarged (after Powell). III. STIRPS SPHAERIACEA Shell porcellan-like, rounded triangular to oval; main teeth situated below the umbones, sometimes strong, sometimes incompletely developed, in most cases lateral lamellae are also developed; mantle line without or with a weak sinus below the scar of the posterior adductor muscle; ligament external. The mantle, which is open below, forms posteriorly 1293 closed incurrent and excurrent openings, which are sometimes produced into short siphons; gills lamella-shaped, sometimes folded, with variably developed interlamellar septa, posteriorly fused with one another; foot without byssus. In fresh and brackish water. Family 1. Shell more or CORBICULIDAE large and strong, triangular to oval, externally less concentrically striated; with yellow, green, or margin well developed, the umbones and in in brown peristracum; hinge most cases with 3 diverging main teeth belcw most cases with anterior and posterior Posterior mantle opening not or shortly produced; lateral teeth. foot large, hatchet- shaped; both limbs of the kidney arch-shaped, the proximal one lateral to the distal, which communicates with that of the opposite side by a small aperture. In most cases without brood care. A. Subfamily Corbiculinae Ligament external. Polymesoda Rafinesque, 1820 Shell large and strong, with projecting umbones, rounded below, only slightly longer than high, on either side with 3 main teeth, on the left with one anterior and one longer, smooth posterior lateral tooth, corresponding to each of which there are 2 teeth in the right valve. Numerous species in America, Asia, and Oceania. Section Geloina Gray, 1842. Shell roundish to short oval, sometimes with a shallow mantle sinus. P. (G.) ceylanica (Lamarck). — Section Pseudocyrena Bourguignat, 1854 (synonyms Anomala Deshayes, 1854, non Block, 1799, nee Samouelle, 1819; Egeta H. & A. Adams, 1858; Cyrenocapsa P. Fischer, 1 872). Umbo high; shell anteriorly and posteriorly rounded, without mantle sinus. P. (P.) maritima (Orbigny). In brackish water of Central America. —Section Polymesoda s. s. (synonyms Cyprinella Gabb, 1864, non Girard, 1856; Diodus Gabb, 1868; Leptosiphon P. 851 Fischer, 1872). Shell rounded triangular, with rather deep and very narrow mantle sinus. P. (P.) caroliniana Egetaria Morch, Shell 1861. anteriorly (Bosc), in America. shortly rounded, — Section posteriorly elongated and pointed; mantle sinus narrow. P. (E.) pullastra (Morch), in South America. 1294 & Villorita Griffith Synonym Velorita Gray, Pidgeon, 1834 1847. Shell medium-sized, thick, obliquely triangular, posteriorly flattened and angulate below; umbo high; hinge margin very broad, on either side with 3 main teeth, of which the anteriormost right and the posteriormost left are weakly developed; the one forms an angle enclosing situated right anterior lateral tooth is very short, on the broad hinge margin, whereas the corresponding situated it; left the posterior lateral teeth are long, on the posterior margin, the right anterior adductor muscle scar lies closely one anterior to the left; the below the hinge margin, the posterior one at the end of the posterior lateral tooth; anterior to it the mantle line forms a small sinus. The siphons are short, the lower one larger than the upper, at the ends with papillae; foot triangular, anteriorly pointed; inner gill lamina broader than the outer; labial palps narrowly triangular. cyprinoides (Gray), in brackish water in India. V. Batissa Gray, 1852 Shell oval or triangular, projecting; hinge margin broad, teeth transversely large on and strong; the anterior ones striated, umbo either side with 3 short, main left only slightly teeth; lateral single, right double; ligament strongly projecting; mantle line without distinct sinus. Mantle fairly thick, but the marginal part not sharply delimited; foot large, with sharp margin; outer gill and lamina broad; labial palps very broad thin. A B. tenebrosa Hinds. few species on the islands in the Indo-Pacific region. Corbicula Megerle von Muhlfeld, 1811 Shell in most cases fairly small, roundish or oval; projecting; hinge margin moderately broad, teeth; anterior striated, scars and posterior on umbo more or less either side with 3 main lateral teeth long, lamella-shaped, transversely double in the right valve; anterior and posterior adductor muscle nearly equally sized. papillae; inner gill Siphons only slightly different, without lamina broader than the outer; foot triangular; labial palps pointed. Subgenus Corbicula s. s. Without mantle sinus and brood care. (synonym Cyrena Lamarck, 1818). Shell in most strong and concentrically sculptured. C. (C.) fluminalis Section Corbicula cases fairly s. s. 1295 (Muller) (Fig. — Section SI 6). Several Cyrenodonax Asia, species in 1903. Shell Dall, situated at the beginning of the posterior third, (C.) formosana Fig. Dall, Africa, small, and Australia. smooth, thin, somewhat umbo C. inflated. on Formosa. 816. Inner side of the shell left valve of Corbicula fluminalis (Muller). Length 3 cm. Subgenus Cyanocyclas Ferussac, 1818. With brood care. ? Section Corbiculina Dall, 1903. Small and thin; without mantle sinus. C. (C.) angasi Prime, 852 Australia. in Neocorbicula P. Fischer, limosa Maton. A —Section few species The manner of brood is ? Soleilletia Shell small and teeth; S. s. (synonym C. (C) sinus. not known. Bourguignat, 1885 thin, with sharp tooth and 2 elongated swellings; s. South America. in care Cyanocyclas With a small mantle 1887). left umbones; right valve with a central with 2 teeth, without distinct lateral without mantle sinus. Animal unknown. abbadiana Bourguignat. 2 species ? 2. Family in Abyssinia. CYRENOIDIDAE Shell thin, fairly small, roundish, with somewhat projecting umbones situated anterior to the center; hinge margin narrow; thin teeth meeting at an angle, that situated left valve with 2 below the umbo short, the anterior one elongated and curved; the teeth of the right valve clasp the left ones, the upper ones are similar to these, below this lies an angular lamella; lateral teeth absent; muscle scars and the nonsinuate mantle line 1296 very shallow. Siphons fairly long, fused;' laminae dissimilar; foot gill club-shaped; labial palps triangular; proximal limb of the kidneys partly lateral to the outer sack, which passes it forms 2 sacks and 3 lobes, the median of into the tube-shaped distal limb. Cyrenoida Joannis, 1835 Synonyms Cyrenella Deshayes, 1836; Cyrenodonta H. & A. Adams, 1858. Characters of the family. C. dupontia Joannis. Few and Central America; Africa, species in Australia, the Philippines, Pilsbry wants to place this group in the Lucinacea; position is West in rivers. systematic its uncertain. 3. Family SPHAERIIDAE Shell thin and small, permeated by fine pores, into which thread- shaped processes of the mantle epithelium extend; hinge margin very narrow; main teeth differing in the two valves, at most 2 on either side, the right ones are fused to form an obtusely angled or elongated lamella, separate in the left valve; lateral teeth elongated. Mantle margin smooth, it forms 1 or 2 smooth-margined siphons. Foot tongue-shaped; the gill laminae are fused exteriorly with the mantle, interiorly with the visceral sack, and posteriorly with one another; the outer lamella of the inner lamina forms few brood pouches, in which the small number of young ones produced attain a fairly considerable size; the kidneys form repeatedly coiled ducts; gonads hermaphroditic. The sphaeriids inhabit the fresh waters of ? all Pseudocorbicula Dautzenberg, 1908 Shell fairly solid-walled, oval, with projecting the center; right valve with a rudimentary these; anteriorly and posteriorly on the 853 on the main left umbones tooth, left situated in one with 2 of a smooth, fairly short lateral Animal unknown. alluaudi Dautzenberg, in Lake Victoria (Africa). tooth, 2 of these P. continents. right. Pisidium C. Pfeiffer, 1821 Synonyms Pisum Megerle von Muhlfeld, 1811 (non Pison Spinola, + Pera + Cordula Leach, 1852. 1808); Galileia O. G. Costa, 1840; Euglesa 1297 most cases very small; umbo closer Shell in to the posterior end; ligament internal; main teeth of the right valve fused to form a curved lamella, in the left valve angular or arcuate; lateral teeth 1 on the left, 2 on the right. The genus is distributed over all Several subgroups have found named: Fluminina amnicum for P. continents. (Miiller) supinum A. Schmidt, and Fossarina P. Fossarina A. Adams & = Pisidium s. s., Rivulina for for P. obtusale C. Pfeiffer (non Angas, 1863) (= Cycladina Clessing, 1871, non 1825, nee Cantraine, Latreille, 1873, has acceptance; Clessin, little 1835); 1903, named: Dall, Phymesoda Rafmesque, 1820, for P. virginicum (Gmelin); Cyclocalyx Dall for P. Clessin = obtusale C. scholtzii Tropidocyclas Dall Pfeiffer; for P. henslowianum Sheppard, recognized as a synonym of Fossarina (Clessin, and Cymatocyclas Dall for P. compressum Prime; besides Rivulina and Fossarina, 1916, named: Sterki, Fontinalina for P. fontinale C. subgenus Pseudeupera for the African idahoense Roper; 1913, proposed a P. landeroini Germain; Clessinia 1912 (non Doring, 1877), as a section of Fossarina, has been Piaget, named for P. Germain, Lacustrina Pfeiffer; as Cletella by Strand, 1928. Odhner, 1921, divided the genus into s. s.) for P. (P.) amnicum (Miiller), with 2 subgenera: Eupisidum (= Pisidum 2 gills on either side either side and with 2 siphons, and Neopisidium with one gill on and with only one (the anal) siphon. P. (N.) torquatum Stelfox. Sphaerium Scopoli, 1777 Synonyms Nux Mus. Calonn., 1797; Cyclas Lamarck, 1798; Cornea Megerle von Miihlfeld, Clessin, 1811; 1890, non Held, Shell in most cases Corneocyclas Ferussac, fairly small, oval; umbo valve with a sometimes cleft main tooth, which left. Corneola close to the center; right is clasped by 2 oblique teeth of the left valve; lateral teeth lamella-shaped, 2 the 1818; 1837. Siphons unequally long, fused at on the right, 1 on the base. Several species in America, Europe, Africa and northern Asia. Section Sphaeriastrum Bourguignat, 1854. Shell fairly strong; hinge margin distinctly developed; ligament external, projecting. S. (S.) rivicola Amesoda Rafmesque, 1820 (= Amesodon L. Agassiz, 1847; Sulcastrum Sterki, 1930) for S. simile (Say) = sulcatum (Lamarck) is (Leach). similar, only with flat ligament — and with rough, finely wrinkled surface. Section Cyrenastrum Bourguignat, 1854. Shell strong, distinctly ribbed; ligament internal. S. (C.) solidum (Normand). Serratisphaerium Germain, 1909, for Sphaerium S. courteti Germain, s. s. has denticulate lateral teeth. Shell fairly weak, with rounded — umbones; ligament Section internal. 1298 corneum (Linne). S. (S.) — Section Musculium Link, 1807 (synonyms Calyculina Clessin, 1871; Primella Cooper, 1891). Shell very thin; hinge embryonic plate weak; by a groove. shell projecting, often delimited S. (M.) lacustre (Muller). Byssanodonta Orbigny, 1846 Synonyms Eupera Bourguignat, 1854; Limosina Clessin, 1872; Waagen 1905. Shell small, very thin, rhomboidal; umbo somewhat projecting, Clessinella 854 margin narrow, on either side with situated anterior to the center; hinge small main tooth parallel to the margin, sometimes reduced on the right; in the left fused 1 , in the right 2 lateral teeth anteriorly B. paranensis Orbigny. and and posteriorly. Siphons at base. A few species, and Central America in South Africa. in The typical species is stated to possess a byssus, whereas the African species in most cases live in the cavities of Aetheria shells. IV. Shell teeth smooth or concentrically sculptured; ligament more or external; main less parallel to the margin. 1. Shell STIRPS ISOCARDIACEA variable in concentrically striated; and anteriorly directed, Family size, KELLYELLIDAE roundish, umbo more in oval or angulate, smooth or or less close to the anterior margin most cases fairly projecting, often a lunule is delimited by a furrow; ligament external, weak; hinge variably strong; umbones and a which is sometimes posteriorly triangular, and with its anterior end in most cases above the central tooth, occasionally upon this right valve with a central tooth situated anterior to the main tooth, with a valve which weak tooth-shaped is is indented. it is is variable, sometimes left a shorter or longer tooth not always distinct; the mantle line The mantle main tooth of the thickening; the anterior elongated or angular, posterior to is it without siphons, sometimes with distinct siphons, in is at most cases not completely open, the margin with tentacle-like processes; the gill is thick, with fine filaments which are inwardly greatly broadened, in Vesicomya stearnsi with a narrow outer lamina; the ascending lamellae have free margins; foot ventrally flattened, without byssus; labial palps narrow. Inhabitants of the deep sea. 1299 M. Kellyella Sars, 1870 (Kelliella) Characters of the family. Several species in the depths of various seas. Subgenus Kellyella distinctly siphon short; anal s. s. Shell very small and thin, roundish; lunule Mantle open, posteriorly with marginal tentacles; delimited. gill laminae unequal. K. (K.) miliaris (Philippi) (Fig. 817). Fig. 817. Shell of Kellyella miliaris (Philippi) and the more highly enlarged hinge margins (after Sars). Subgenus Vesicomya 1886. Shell fairly small, roundish; lunule Dall, delimited. K. (V.) atlantica (E. Smith). Subgenus Archivesica Dall, 1908. Shell large, longish, without delimited lunule, without distinct mantle sinus. K. (A.) gigas (Dall). Subgenus Callogonia Dall, 1889. Shell similar to Archivesica, but with distinct mantle sinus; animal unknown. K. (C.) leeana (Gall). ? Veneriglossa Dall, 1886 (synonym Atopodonta Cossmann, 1887). Shell roundish; umbo anteriorly inclined; lunule delimited; the hinge appears to be similiar to that of Vesicomya, hence Veneriglossa identical with Vesicomya; Dall it in the venerids. V. this after he may first be placed vesica (Dall). ? Pauliella 855 had doubts about Munier-Chalmas, 1895 Shell small, roundish, angulate above; umbo only slightly projecting; lunule distinct; ligament external; hinge margin with main teeth similar to those in Kellyella and in each valve with 3 anterior lateral teeth 1300 parallel to the margin; externally with fine concentric rings; mantle line posteriorly weakly indented. P. bernardi Munier-Chalmas, near 2. Family St. Paul Island. ISOCARDIIDAE Shell medium-sized, fairly weak, with very strong, anteriorly inrolled umbones; surface smooth or with concentric sculpture; ligament external; each valve with 2 main teeth which are parallel to one another and partly bilobed and a long posterior lateral tooth, sometimes with rudimentary anterior lateral teeth; mantle line not indented. Mantle with 2 posterior openings, papillose at the margin, without siphons; gill laminae broad, folded; foot hatchet-shaped, with byssus; labial palps narrow. Isocardia (Klein) Lamarck, 1799 Synonyms Glossus + Glossoderma Poli, 1795; Bucardium Megerle von Muhlfeld, 1811; Bucardia Schumacher, 1817. Characters of the family. s. s. (synonym Tychocardia E. Romer, brown periostracum, smooth, without posterior edge. Subgenus Isocardia Shell with humana Atlantic Fig. 1869). /. (/.) (Linne) (Fig. 818), in the Mediterranean Sea and the neighboring Ocean. 818. Inner side of the right shell valve of Isocardia Length 6 cm. humana (Linne). 1301 & Subgenus Miocardia H. A. Adams, 1857 (Meiocardia). Shell without distinct periostracum, with strong edge to a posterior corner, with concentric folds. anterior to it species, in warm V. STIRPS CYPRINACEA Shell oval to elongated; umbo more or less anteriorly shifted, ligament posterior lateral tooth are present; mantle line in main teeth and a most cases without sinus. external; in addition to the right central tooth, posterior Incurrent Few (M.) moltkiana (Spengler). /. seas. and excurrent openings with papillae, without siphons; gill laminae folded; foot with groove. Marine inhabitants. 1. Family CYPRINIDAE roundly oval, bulging, with strong periostracum, finely Shell umbo concentrically striated; margin broad; posterior center; hinge right valve, a deeply anterior to situated to the central tooth of the the furrowed triangular main tooth; a pair of short anterior a long posterior one; left posterior to the central tooth, and one posterior 856 separated from lateral tooth. it lateral teeth and valve with a high, often cleft tooth situated by a triangular field, main which tooth, is in addition with a short anterior Mantle anteriorly open; foot thick, with ventral groove; gill laminae unequally broad, the outer one half-moon-shaped; the proximal of the kidney part is long and narrow, the distal part wide, sack-shaped. Cyprina Lamarck, 1818 Synonyms Arctica Schumacher, 1817 (non Moehring, Gistel, 1848; Asmidia Moerch, 1758); 1853; Cypriniadea Rovereto, Armida 1900. Characters of the family. C. islandica (Linne) (Fig. 819), in the northern Atlantic Ocean. 2. Shell more or less Family LIBITINIDAE elongated, with umbones situated far forward; hinge margin moderately broad or narrow, on either side with 2 main teeth and a posterior, more or with a short anterior lateral small; labial palps short. reefs. less elongated lateral tooth, tooth. The animals on the left also Anterior mantle opening and foot live in caverns of rocky and coral 1302 \ \ i^A~.»_J«**"^ 819. Inner side of the right shell valve of Cyprina islandica (Linne). Fig. Length about 8 cm. Libitina Schumacher, 1817 Synonyms Trapezium Megerle von Muhlfeld, 1811 (non Mus. Calonn., Cypricardia Lamarck, 1797); 1819. Shell strong, trapeze-shaped, with posterior edge and nearly terminal umbones; the central tooth of the right valve is sometimes more sometimes more posteriorly directed, sometimes anterior to it ventrally, a small lateral tooth the two main teeth is developed; the posterior main tooth of the left anterior to the central tooth Few species, in warm is clasped by valve; the left anterior lateral tooth situated is in most cases well developed. seas. Subgenus Glossocardia Stoliczka, 1870. Shell fairly large and inflated, exteriorly concentrically striated; central tooth of the right valve strong, the main tooth lying above it more or valve catching between the two is less bipartite; the triangular, the main tooth of the upper one weak. left L. (G.) obesa (Reeve). Subgenus Libitina s. s. Shell not or only slightly inflated, sometimes radially striated; umbo depressed; the upper main tooth of the right valve simple or cleft; the two main teeth of the left valve simple; right valve with 2 posterior lateral teeth. L. (L.) concentrically and bicarinata Schumacher. Coralliophaga Blainville, 1824 Synonym Lithophagella (Gray) H. Shell much longish, fairly thin, & colorless, A. Adams, 1857. radially striated; closer to the anterior margin; right valve with 2, in umbo low, most cases 1303 main main parallel, parallel 857 lateral tooth; muscle scar. teeth and one posterior small a teeth, anterior tooth; lateral left valve with 2 one and an elongated posterior mantle line with a sinus below the posterior adductor C. coralliophaga (Chemnitz). Few warm species, in seas. Isorropodon Sturany, 1896 Shell small, elongated oval, concentrically striated; on the anterior end; hinge margin narrow; to one another, the lower of which posterior lateral tooth; on posterior main right with 2 lies anterior to umbo closer to the main teeth parallel the umbo, and a the left with a bipartite anterior thin and a thin tooth, as well as a ridge-shaped posterior lateral tooth; mantle sinus weak. /. perplexutn Sturany, in the eastern Mediterranean Sea (deep sea). VI. A STIRPS CYAMIACEA group of small bivalves, which and have been so far mostly live mainly in the southern seas classified with the Erycinacea, from which they differ by the presence of 2 posterior mantle openings; they have 2 gill laminae on either side and a byssal gland in the foot; an internal ligament is in most cases present, but sometimes does not seem be to separated from the external one. 1. and Shell small radial sculpture, Family thin, in more or CYAMIIDAE most cases internal, short cartilage, anterior to on the Mantle ventrally open, posteriorly with 2 lower of which bears marginal papillae; one very broad; pointed, with gill sometimes with fine hinge margin weak, with which on the distinct bipartite tooth; correspondingly it. colorless, less strongly bulging; right is a left fairly large less openings, the laminae folded, the inner labial palps small, triangular; foot fairly long, anteriorly small byssal pit; anterior adductor muscle somewhat smaller than the posterior; sexes separate, in the inner is more or are 2 teeth clasping sometimes brood gill lamina there care. Cyamiomactra Bernard, 1897 Shell very small, in most cases longer than broad, smooth or with radial striae; ligamental cartilage elongated; slanting; right valve with 2 1304 main which are continuous above and 2 anterior and posterior teeth lateral teeth; left it valve with a ventrally cleft main tooth and posterior to a thin main tooth; elevated, posterior anterior lateral one elongated; inner tooth at the beginning greatly margin smooth or denticulate. shell Animal unknown. C. problematica New Bernard (Fig. 820). Few near Australia, species, Zealand, and in the Antarctic Ocean. Fig. 820. Hinge margins of Cyamiomactra problematica Bernard, enlarged (after Bernard). Perrierina Bernard, 1897 Shell very small, irregularly roundish, thin, smooth; cartilage internal, short; hinge margin angle-shaped main tooth, on the 858 it left fairly ligamental narrow; on the right with a with a forked one and posterior to a thin main tooth, as well as with a short anterior and posterior lateral tooth; anterior and posterior to the hinge teeth are a few marginal denticles as indications of radial ribs. P. taxodonta Bernard, near the Steward Islands and one species [fragillima (Thiele)] from Kerguelen. Cyamium Shell elongated oval; partly external, Philippi, umbo more partly internal, 1845 or less anteriorly shifted; ligament the latter part sometimes triangular, sometimes more elongated; hinge teeth variable, when fully developed similar to those in Perrierina: on the right with an angle-shaped tooth, corresponding to which on the posterior to it left is a forked one and anterior and one short tooth each, sometimes the teeth are weak, 2 on either side; mantle line unindented. The mantle forms an opening for the byssus-bearing foot; a wide opening at the posterior end without siphons, 1305 and above one fairly C. it an excurrent opening; on either side 2 antarcticum Philippi. A few species, Legrandina Tate Shell gill laminae, the outer narrow. & in the Antarctic May, 1901 very small, oval, angulate above, with indications of a fine radial sculpture; ligamental cartilage oblique, anterior to a main tooth, corresponding to which on the anterior and posterior to the hinge teeth denticles. L. Ocean. is left on the it right are 2 diverging teeth; a small number of marginal Animal unknown. & bernardi Tate May, near Tasmania. Pseudokellya Pelseneer, 1903 somewhat Shell roundish or radial sculpture; margin posterior to anterior hinge teeth P. angular, uniformly bulging, with umbo moderately ligament prolonged somewhat ridge-shaped; the of the weak elevated, situated in the center; hinge left valve fairly long, diverging in an acute angle. Few cardiformis (Edg. Smith). species, in the Antarctic Ocean. Ptychocardia Thiele, 1912 Shell somewhat higher than long, with high, anteriorly directed umbones, peculiarly angular, with a strong median fold and with numerous small radial folds; ligamental cartilage small; hinge teeth of the left distinct P. valve short, the posterior one angle-shaped; right valve with a bipartite tooth, anterior part angle-shaped. Animal unknown. vanhoffeni Thiele (Fig. 821). 2 Antarctic species. Turtcnia Alder, 1848 ? Shell small, smooth, brown, not gaping; umbo situated anterior to the center; ligament only external; hinge margin on either side with 2 anterior teeth and with a more or corresponding to which is less distinct posterior lateral a furrow in the other valve. tooth, Mantle open below; incurrent opening not separated from the anterior one; excurrent opening only slightly projecting; gill laminae unequal; foot fairly long, with byssus. T. minuta (Fabricius), The systematic in the northern position of Turtonia similarity with Kellyella; the hinge is is seas. uncertain; the shell has similar to that of certain little Cyamium 1306 M ^..iii &P .'— 858 Fig. 821. Ptychocardia vanhoffeni Thiele. inner and outer side of the left shell valve; b, a, c, the hinge margins, more strongly enlarged. species, but it lacks the internal ligament and the animal differs by the wide open mantle. 2. Family SPORTELLIDAE Dall established the family Sportellidae without sufficient diagnosis; he included the genera Sportella Deshayes, Anisodonta Deshayes, and Hindsiella Stoliczka, which are mainly Tertiary species; P. Fischer included some of them in the Galeommatidae, and some near Libitina. From the former it is distinguishable, according to Dall, by the absence of the mantle cover on the shell surface; the animal, known only in the case of Anisodonta (Basterotia) quadrata (Hinds), has a fairly small 1307 opening for the foot and posteriorly 2 openings. with Cyamium, and it but the ligament in is is most cases only Synonym Fabella Conrad, posterior end; ligament on a 1858 more or umbo most cases closer in f- to the less distinct ridge; cartilage resting on a thickening; hinge margin on either side with 2 dubia (Deshayes) agrees 1863. Shell transversely oval, smooth; S. it external. Sportella Deshayes, in a pit or In this respect possible that they are related with that genus, teeth. Dall has described a few recent Californian species and 2 from North Carolina. Anisodonta Deshayes, 1858 Umbo more ligament short; or less close to the anterior margin; hinge margin on either side with one tooth. Section Fulcrella Cossmann, 1886. Shell rounded rectangular, only slightly larger gaping, without posterior edge; ligament elongated, without intervening space along the slightly projecting teeth. A. paradoxa (Deshayes) Carolina and the West Indies. — Section Anisodonta s. s. Shell longish, with more or less strong posterior edge, only slightly gaping; slightly projecting; projecting; — teeth (F.) Dall included a couple of species from North fl surface rough; umbo only ligament support fairly long, not moderately strong. A. (A.) complanata Deshayes f- Section Basterotia C. Mayer, 1859 (synonym Eucharis Recluz, 1850, non Latreille, 1804). Shell inflated, posteriorly and ventrally more or less gaping, posteriorly angular; support of the ligament short, separated from the projecting teeth by an intervening space. Mantle margin beset with papillae; foot small, tongue-shaped, with a furrow; labial palps short; gill laminae unequally broad, posteriorly fused. A. (B.) corbuloides (Homes) a few living species in 3. warmer Family f; seas. NEOLEPTONIDAE Shell very small, with internal ligamental cartilage; left valve with an angle-shaped, elongated anterior tooth, which is clasped by 2 teeth of the right valve, and a posterior lamella on either side. Mantle without tentacles, anteriorly and ventrally open, posteriorly with 2 slightly elongated openings with marginal papillae; foot anteriorly and posteriorly somewhat prolonged, without byssal pit; outer gill lamina very narrow, mainly formed of the ascending lamella; both laminae smooth. 1308 Neolepton Monterosato, 1875 Shell angulate above, concentrically striated; oval, close to the center; hinge margin the left on the umbo situated one main tooth, on right with with 2 of these; the posterior lamella of the right valve corresponds to a pit of the Velain, Lutetina according to Bernard, 1927 (antipodum left. 1876 {antarctica Velain, from is (Filhol), St. Paul Island), not substantially different; Notolepton Finlay, from New Zealand) is also scarcely separable. N. sulcatulum (Jeffreys), in European seas. Epilepton Dall, 1899, is similar to Neolepton; cartilage in a slanting posterior furrow; hinge on either side with a simple posterior and a hook- shaped anterior lamella. E. clarkiae (Jeffreys). Monterosato, 1909, proposed a group Arculus for Lepton sykesii Chaster. Davisia J. E. Cooper & Preston, 1910 (non Del Guercio, 1909), likewise does not appear to differ significantly from Neolepton. D. cobbi Cooper & Preston, from the Falkland Islands. Pachykellya Bernard, 1898 Shell very small, thick, higher than long, angulate above, posteriorly shorter than anteriorly, smooth; ligament internal; hinge margin inwardly delimited by ridges, since the similar to those of Neolepton. and P. edwardsi Bernard in Foveaux (Fig. umbones are not hollowed; hinge Animal unknown. 822). Few species, near Stewart teeth Island Strait. Hinge margins of Pachykellya edwardsi Bernard, enlarged Fig. 822. (after Bernard). Puysegeria Powell, 1927 Shell obliquely oval; right valve with a long anterior lamella, is hook-shaped anterior lamella; triangular P. left to the cartilage, and a more or which less short posterior valve with a strong, hook-shaped anterior lamella, main tooth, and a posterior tubercle. cuneata Powell. 2 species, near New Zealand. a 1309 VII. Shell with STIRPS GAIMARDIACEA umbones more or less close to the anterior end; hinge weak. Mantle with 3 openings; foot small, with a byssal gland; the eggs developed (always Marine. ?) in the gills. 861 1. Family Shell thin, smooth, in GAIMARDIIDAE most cases small, brown; umbo more or close to the anterior end, which is less somewhat pointed; ligament most cases on either side with often external or sunken; hinge margin weak, in one main tooth, but which may however be completely absent; mantle line without sinus. Mantle with an anterior opening for the foot and 2 posterior openings; laminae smooth or folded; foot with byssus; gill pericardial limb of the kidney long and narrow, distal part sack-shaped, largely situated below the pericardium, posteriorly with lobes, which surround the foot retractor; interconnenction of the two kidneys sometimes long and wide, sometimes not present. Eugaimardia Cotton, 1931 Synonym Neogaimardia Cotton, Shell small, umbo situated close 1931, non N. Odhner, 1924. to the roundly-angled anterior end, directed anteriorly; ligament external; right valve with a central tooth, surrounded by two dorsally continuous which is tooth; left teeth, and one posterior valve? Animal unknown. E. perplexa (Cotton), near South Australia. Gaimardia Gould, 1852 Shell in to most cases small, the anterior end, thin, oval or trapeze-shaped; somewhat sunken; hinge margin weak, on tooth, which surrounds a denticle of the laminae on either A umbo close sometimes nearly terminal; ligament external or the right with left valve, an angular often toothless; 2 gill side. few species, in southern seas. Subgenus Gaimardia s. s. (synonyms Modiolarca Gray, 1847 (non 1843); Phaseolicama Valenciennes, 1854). Shell trapeze-shaped; ligament external or somewhat sunken; gill laminae folded, with interlamellar septa; ventral mantle fusion shorter than the incurrent opening; anterior foot gland separated flattened sole-like. from the byssal groove; anterior part of the foot G. (G.) trapezina (Lamarck) (Fig. 823). 1310 y Fig. 823. Inner side of the Subgenus Kidderia sunken; gill Dall, 1876. of Gaimardia trapezina (Lamarck). Shell mantle fusion longer than the two posterior openings together; anterior foot gland opening into the Section Kidderia Costokidderia (N. s. end of the byssal groove. smooth. G. (K.) minuta (Dall). Shell s. 1927. Finlay, with radial Shell folds. — Section G. (C.) costata Odhner). ? Shell part ligament somewhat longish; laminae smooth; interlamellar septa only in the marginal ventral part; right shell valve small, Neogaimardia N. Odhner, 1924 with nearly centrally placed umbones; oval, somewhat beak-shaped because of a and one tooth above right valve with central tooth hook-shaped tooth. Outer gill anterior ventral sinus; ligament internal; it; left valve with a lamina reduced; anterior mantle opening small; incurrent opening ventral, long; anterior foot gland separated from the byssal groove. N. rostellata (Tate). 862 Few Family ? 2. Shell small, oval; species, near Australia umbo more and New Zealand. JULIIDAE or less anteriorly positioned; ligament external, marginal; nearly in the center scar of an adductor muscle. the two genera is of the inner side lies the roundish Animal unknown. The systematic position of uncertain. Julia Gould, Synonym Prasina Deshayes, 1863. Shell fairly strong, green, covered; and forwardly inclined, on the lunule is 1862 umbo close to the anterior end right side with a small spiral process; the deeply sunken and in both valves has a tooth-like thickening of the margin, corresponding to a pit of the other valve; the thickening in the right valve lies above the J. exquisita Gould. Few pit, in the left valve species, in the Pacific below it. and Indian Oceans. 1311 ? Edenttellina Gatliff & Synonym Ludovicia Cossmann, = Ludovicius Rondani, 1843. Gabriel, 1911 non Marschall, 1873 Shell thin, yellow, smooth, flattened, oval, anteriorly pointed, umbo more or situated 1888, less anterior to the center; on the right with a spiral process; in the right valve with a tooth-shaped thickening of the anterior hinge margin, corresponding to a pit of the left lunule not valve; deepened. N. typica Gatliff & Gabriel. 2 species, on the Australian coasts. STIRPS DREISSENACEA VIII. Shell anteriorly pointed, with completely or nearly terminal umbones, ventrally flattened; periostracum strong; inner side not nacreous; ligament marginal, somewhat sunken; hinge margin anterior corner on either attaches; scar of byssal side, to toothless; a septum in the which the anterior adductor muscle muscle long and narrow. The mantle below has an opening for the foot and posteriorly 2 short siphons, the lower one of which is larger; with papillae on the margin; foot with byssus; the gill laminae are nearly equally broad, smooth, with a few interlamellar septa, posteriorly fused with one another; pericardial limb of the kidney long and narrow; distal limb anteriorly low, interconnected, posteriorly bilobed, surrounding the byssal muscle. Development with free ciliated larvae. In fresh-water. Dreissena van Beneden, 1835 (Driessena) P. Characters of the family. Several species, in Europe, Asia, Africa, and America. Subgenus Dreissena Mytilina Cantraine, s. s. (synonyms Tichogonia Rossmaessler, 1835; 1837; Mytilomya (Cantraine) Bronn, 1838). Shell without process for the attachment of the anterior foot muscle. D. (D.) polymorpha (Pallas). Subgenus Congeria Partsch, 1836 (synonym Enocephalus Minister, 1831, nom. nud.). Shell with a process for the attachment of the anterior foot muscle on the septum. Typical species, D. (C.) subglobosa (Partsch), 863 fossil, quadrangular, thick. Praxis H. & — Section Mytilopsis Conrad, 1857 (synonyms A. Adams, 1857; Mytiloides Conrad, 1874, non Brongniart, 1822). Shell elongated, thin. D. (M.) leucophaeata (Conrad). 1312 IX. Shell in seldom are STIRPS LUCINACEA most cases roundish; the all right central tooth absent, and not hinge teeth reduced. The mantle as a rule has 2 posterior openings, seldom the upper one and invaginable, without shaped, seldom short; elongated somewhat funnel-shaped is retractor; foot in most cases long and worm- laminae smooth or weakly folded; sexes gill separate. Family 1. Shell UNGULINIDAE small or moderately large, in most cases without distinct sculpture, roundish; umbo only slightly elevated; hinge margin as a rule on either side with 2 teeth or toothless; ligament more or less sunken; mantle line unindented; adductor muscle scars narrow, the anterior one continuous with the mantle line; shell margin smooth. The mantle posteriorly has a small incurrent aperture and a larger excurrent aperture; the foot is long, often swollen at the end; labial palps different; gills on either side with 2 laminae. A. Subfamily Ungulininae Hinge teeth present. Diplodonta Bronn, 1831 Synonyms Mysia T. Bronn, 1833 (non (Leach) Lamarck, 1818); Gloconome Leach, 1852; Cycladicama Valenciennes, 1854; Mittrea Gray, 1854. Shell lunule; roundish, equivalve, completely covered, without distinct ligament and cartilage external, on a more or less projecting ridge; each valve with 2 teeth, of which the anterior of the posterior of the right valve divided by a furrow. Excurrent opening is left and the without siphon; labial palps fairly large. Several species, mainly in Section Diplodonta umbo somewhat s. s. warmer seas. Shell moderately bulging, without lunule; elevated; surface only with growth lines; hinge margin anteriorly prolonged ridge-shaped. D. {£>.) lupinus Brocchi. Finlay, 1927, proposed a "genus" Zemysia for D. zelandica (Gray) and a subgenus Zemysina for D. globus Finlay, related to the Australian D. globularis (Lamarck). small — lunule; Section Felania Recluz, surface with growth 1851. lines; Shell lens-shaped, with a hinge margin anteriorly and 1313 posteriorly prolonged ridge-shaped. D. (F.) diaphana (Gmelin). Sphaerella Conrad, 1838. Shell large, much indicated by a furrow; posterior right hinge tooth oblique than that in Diplodonta (5.) verrilli 1899. Shell Dall = turgida s. D. s. & Verrill — concentrically striated; (S.) larger subvexa Conrad Smith. — Section lunule and more tl living D. Section Felaniella Dall, compressed, smooth, with distinct periostracum; external ligament longer than the cartilage. D. (F.) usta (Gould). Numella Iredale, 1924, proposed for D. adamsi (Angas), appears to be related to Felaniella. — Section Phlyctiderma Dall, 1899. Shell fairly small, strongly bulging; surface sculptured with small warts or dots or crossed lines. D. (P.) semiaspera Philippi. Joannisiella Dall, 1895 864 Synonym Joannisia Dall, 1895, non Monterosato, 1884, nee Kieffer, 1894. Shell thin, with distinct periostracum and growth lines; hinge teeth as in Diplodonta; ligamental cartilage fairly deeply sunken. Animal unknown. J. oblonga (Hanley). Few species, in brackish water of the Philippines and Australia. Ungulina Daudin, 1802 Synonym Clotho Basterot, 1825, non Faujas de S.-Fond, 1808. somewhat irregularly roundish, smooth or concentrically striated, with more or less strong periostracum; umbo anteriorly directed; the Shell ligament and the cartilage situated in 2 deep pits lying one behind the other; the smaller hinge tooth of both valves developed. is Excurrent aperture with short tube; in most cases weakly oral lobes small and pointed. U. rubra Daudin. A couple of species on the African west coast, in holes of reefs. B. Subfamily Thyasirinae Shell in most cases small and thin, roundish or angulate, often with hinge toothless or with indications of teeth. Mantle with a posterior opening; foot very long; liver and gonads situated in lateral bulges of the visceral sack; the kidneys are longish a posterior radial fold; sacks anterior to the foot retractors and posterior to the pericardium, interconnected; proximal limbs long and narrow. 1314 Thyasira (Leach) Lamarck, 1818 Synonyms Axinus Sowerby, J. Cryptodon Turton, 1818; 1822; Bequania (Leach) T. Brown, 1827; Ptychina Philippi, 1836; Clausina Jeffreys, 1837 (non T. Brown, 1827); Thyatira (Leach) Gray, 1847 (non Hubner, 1816); Conchocele Gabb, Shell umbo posterior radial folds; lunule sometimes is 1866. roundish or angulate, colorless, smooth, often with anteriorly directed; a small broad or 2 1 and short deeply sunken and on the right indistinct, but often forming a tooth-shaped projection; ligament and cartilage fused, the in a furrow; latter situated hinge margin toothless. Several species, in various seas. Section Thysira s. s. more or Shell with dorsal, less distinct fields; posterior field furrowed or folded. T. (T.) flexuosa (Montagu) (Fig. 824). — Section Philis P. hemispherical & pit. 1861. Fischer, T. (P.) cumingi Lunule greatly sunken, forming a (P. Fischer). — Section Axinulus Verrill Bush, 1898. Shell small, roundish or transversely oval, without distinct dorsal fields. Axinodon T. Verrill brevis (A.) & Bush, substantially different, (Verrill 1898 likewise & Bush). [elliptica According (Verrill Genaxinus Iredale, & to Bush)] Dall, is not 1930 (albigena Hedley). Fig. 824. Shell of Thyasira flexuosa (Montagu), enlarged (after Sars). It is Iredale, not clear as to how the "genera" Parathyasira and Prothyasira 1930, are separable. Leptaxinus Verrill 865 & Bush, 1 898 Shell with a weak posterior fold; ligament largely internal; hinge margin somewhat thickened, on the left forming a blunt denticle and a posterior lateral tooth, on the right a weak anterior and posterior lateral tooth. L. minutus Verrill & Bush, in the northern Atlantic Ocean. 1315 Axinopsis G. O. Sars, 1878 Shell small, roundish, bulging, without posterior depression of the dorsum; ligament narrow, a more or margin of the internal; hinge right valve with less strong tooth-shaped projection. A. orbiculata G. O. Sars. 2. Few species, mainly in cold seas. LUCINIDAE Family smooth Shell of variable size, equivalve, roundish or transversely oval, or with distinct concentric, sometimes also radial sculpture; not seldom an anterior and a posterior by furrows or field are delimited small, closely approximated, anteriorly directed; lunule in folds; umbones most cases small, depressed, asymmetrical; ligament in most cases fused with the cartilage, long, marginal, side with 2 seldom completely main teeth internal; hinge margin as a rule on either and with an anterior and posterior lateral tooth the right valve, to which 2 teeth of the left valve correspond; of these teeth may disappear; the anterior muscle scar is some or of all long and narrow, more roundish and situated higher; inner margin smooth, occasionally denticulate. The mantle has 2 posterior openings, the upper of which may be more or less elongated, but this tube has no retractors; the foot is in most cases long and worm-shaped but occasionally short; labial palps very small; the situated outer gill within the mantle line; the posterior one lamina absent, the inner and the gonads situated lie is large in lateral bulges and thick; sometimes the liver of the visceral sack; the kidneys, between the pericardium and the posterior adductor muscle, traversed by the median foot retractors; they are higher than long, joined with one another, proximal part short; sexes separate. Phacoides Blainville, 1825 Synonym Egraca Leach, 1852. Shell strong, roundish, colorless, with sometimes also main teeth on more or less distinct, concentric, radial sculpture; ligament external; hinge either side margin with 2 and with anterior and posterior Several species, mainly in warm lateral teeth. seas. Subgenus Parvilucina Dall, 1901. Shell small, strongly bulging, more or less strongly sculptured; hinge teeth complete; lower margin denticulate. Section Parvilucina s. s. Sculpture weak; anterior and posterior field (Carpenter). — and posterior only slightly or not delimited. P. (P.) tenuisculptus Section Bellucina field Dall, 1901. distinctly demarcated. P. Sculpture strong; (B.) anterior eucosmia Dall. 1316 Subgenus Linga Gregorio, 1885. Shell nearly anterior and sculpture; Cavilucina P. Fischer, striated; 1 spherical, with concentric more or posterior field less Section distinct. 887. Shell small, moderately bulging, concentrically and teeth often weak; lunule small, often deep. P. (C.) fields — 866 sulcata (Lamarck) t; few living species. Section Pleurolucina Dall, 1901. Shell with fine concentric sculpture and few strong radial folds. P. (P). leucocyma (Dall). — Section Linga s. s. Shell very strong, spherical, with concentric lamellae and distinct dorsal fields. P. (L.) columbella (Lamarck) (Fig. 825). Fig. 825. Inner side of the right shell valve of Phacoides (Linga) columbella (Lamarck). Subgenus Lucinoma Dall, 1901. Shell in most cases large, lensshaped, with concentric striae or lamellae and distinct periostracum; main teeth smooth. P. well developed; lateral teeth rudimentary; (L.) filosus (Stimpson). A few species, lower margin mainly in cold and deep water. Subgenus Callucina Dall, 1901. Shell oval; dorsal fields indistinct; lunule small. Section Epilucina Dall, 1901. Sculpture weak; hinge teeth complete; lower margin smooth. P. (E.) californicus (Conrad). Callucina s. s. Shell with concentric threads, sometimes with — Section weak radial each valve with only one main tooth; lower margin folded. P. (C.) radians (Conrad). Section Lucinisca Dall, 1901. Shell with sculpture; — regular rough concentric and radial reticulate sculpture; dorsal fields main tooth rudimentary. P. (L.) nassula (Conrad). Subgenus Phacoides s. s. (synonym Dentilucina P. Fischer, 1887). distinct; right anterior Shell fairly large, lens-shaped, with distinct dorsal fields and concentric sculpture; main teeth pectinatus (Gmelin). of full-grown shell weakly developed. P. (P.) 1317 Miltha H. Shell large, & A. Adams, 1857 somewhat inequivalve; one valve often more bulging than the other, concentrically sculptured; dorsal fields indistinct, with a more or less deep posterior furrow; lunule very small; ligament radial deeply sunken, but not internal; main teeth well developed; lateral teeth rudimentary. M. childreni (Gray). Few species, in warm seas. Myrtea Turton, 1822 Synonym Cyrachaea Leach, Shell fairly 1852. compressed, oval or somewhat angulate, with small, concentric sculpture, without delimited dorsal fields; lunule depressed; ligament sunken but not internal; right valve in most cases with with 2 main teeth; the Few lateral teeth of the left 1, left valve often indistinct. species, in various seas. Section Myrtea Shell without radial sculpture. s. s. M. (M.) spinifera (Montagu). Iredale, 1924, erected the genus Notomyrtea for M. botanica Hedley. — Section Eulopia Dall, 1901. Surface with fine radial sculpture between concentric lamellae. M. (E.) sagrinata 1880 Divaricella Martens, more or Shell colorless, roundish, (Dall). less strongly bulging, sculptured with arch-shaped ridges, which meet angularly in a radial line, without dorsal distinct fields; either side with 2 anterior ones in lunule small, deply depressed; main teeth and somewhat variable most cases weak and close to the hinge margin on lateral main teeth, the teeth; posterior ones sometimes rudimentary. A few species, in various seas. Section Divaricella s. s. Ligament and cartilage fused, sunken in a groove, but not internal; dorsal fields not recognizable. D. (D.) angulifera Martens = quadrisulcata (Orbigny). Shell greatly bulging; D. (P.) gibba (Gray). dorsal — fields — Section Pompholigina Dall, 1901. weakly marked; ligament external. Section Lucinella Monterosato, ligament reduced; cartilage internal, in an oblique pit. D. 1883. External (L.) divaricata (Linne). Loripes Poli, 1791 Synonyms Ligula Menke, 1830; Lucinida Orbigny, 1846. 1318 roundish, Shell concentrically striated; thin, fairly dorsal fields scarcely indicated; lunule narrow and deep; cartilage separated from the ligament, completely internal; right valve with only one main tooth, the left with 2 of these; anterior lateral teeth often rudimentary, the posterior ones most cases absent. in L. A lacteus Poli. Iredale, few species, in various seas. 1930, proposed the following "genera": Monitilora Lucina ramsayi Edg. Smith, Wallucina for L. jacksoniensis and Nevenulora for Lucinida hilaira Hedley. Elathia only one main tooth on either for Edg. Smith, 1869, has Issel, side. E. arconatii Issel, in the Red Sea. Megaxinus Brugnone, 1880 umbo roundish, concentrically striated; Shell anteriorly inclined; ligament externally visible, with projecting ridges; hinge margin toothless. Few species, in warm seas. Section Pseudomiltha P. dorsal fields in — Section Megaxinus without dorsal Fischer, 1887. Shell most cases delimited. M. s. s. more or (P.) giganteus Shell fairly small and less large; (Deshayes) f- thin, anteriorly angulate, M. (M.) transversus (Bronn). fields. Lucina Lamarck, 1799 Synonym Anodontia Link, 1807. more or less large, fairly thin, roundish, bulging, concentrically striated, without dorsal fields; umbo only slightly projecting; ligament Shell sunken in an oblique furrow, with few elevated ridges; hinge margin toothless. Section Lucina s. Shell in s. most cases large; lunule fairly long and narrow; ligament distinctly external; anterior muscle scar long. L. (L.) edentula (Linne) (Fig. 826). Few species, in warm seas. Iredale, 1930, erected a genus Prophetilora for the Australian arizela Iredale, and a genus Cavatidens for his omissa. Shell small, inflated, thin; — Section Loripinus Monterosato, 1883. lunule broad and short; ligament almost completely internal; anterior muscle scar broad and short; foot short. L. (L.) fragilis Philippi, in the Mediterranean Sea. ? Shell fairly small, roundish; ligament Vaticinaria Dall, 1901 very thin, without distinct sculpture, irregularly more or less sunken; hinge margin toothless. Mantle with a posterior opening; foot short, with byssal groove; gills on either 1319 826. Inner side of the right shell valve of Lucina edentula (Linne). Fig. Length 8 cm. side with only one lamina, posteriorly fused with one another; muscle scar oval; oral lobes small; anterior mantle margin thickened. V. A moseleyi (Edg. Smith). couple of deep-sea species. For a very small Australian species: Lucina induta Hedley (non Stoliczka), Iredale, which in Hedley's opinion perhaps belongs to Vaticinaria, named the species 1924, has erected a genus Mendicula and M. memorata; the animal unknown. is Codokia Scopoli, 1777 (Codakia) Synonyms Lentillaria Schumacher, 1817 (= Lenticularia Gray, 1847 = Lintellaria Bucquoy, Dautzenberg Megerle von Muhlfeld, Fischer, 1811; Anfilla & Dollfus, 1898); Orbiculus 1884 (= Antilla Gregorio, P. 1887). Shell of variable size, roundish, lens-shaped, exteriorly with radial and concentric sculpture, interiorly often colored, without dorsal fields; umbo forwardly directed; hinge margin in most cases with 2 undivided main teeth on either side; lateral teeth may be absent. Several species, in various seas. Subgenus Jagonia Recluz, 1869. Shell sculpture stronger; anterior and pointed. lunule fairly large; posterior lateral teeth fairly small and thin, radial ligament and cartilage external; distinct; foot very short, anteriorly C. (J.) orbiculata (Montagu). Subgenus Codokia s. s. Shell fairly large and strong, latticed; lunule very small; ligament and cartilage large, deeply sunken, exteriorly covered by a calcareous accessory gill layer. Foot short; at the anterior part of the mantle is an consisting of a few thin lamellae; siphon short or absent; anterior to the mouth opening is a glandular tube. C. (C.) orbicularis 1320 (Linne). main erected a group Pexocodakia 1930, Iredale, (Reeve); more oblique; muscle teeth scars C.rugifera for longer; sculpture stronger. Subgenus Pillucina radial sculpture; umbo Pilsbry, 1920. Shell small, strongly bulging, with fairly high; lunule small; ligament short, internal; hinge margin on either side with one main tooth; anterior adductor muscle absent; unknown. C. lateral teeth scar only slightly elongated. weak or Animal (P.) spaldingi (Pilsbry). For a similar Australian species, which Iredale named symbolica, he in 1930 proposed a genus Sydlorina, and a genus Epicodakia for consettiana Iredale = Lucina minima Tenison-Woods, with strong radial sculpture and strong main and lateral teeth. Corbis Cuvier, 1817 Synonyms Fimbria Megerle von 1761); Idothea Schumacher, 1811 (non Bohadsch, very strong, transversely oval, inflated, sculptured with con- Shell centric Miihlfeld, 1817 (non Fabricius, 1793). and intervening radial ridges; umbo almost median in position; lunule depressed; ligament partly external, partly sunken; hinge margin on either side with 2 main teeth and anterior and posterior the latter of which are placed far from the scar 869 downwardly broadened, large, the main lateral teeth, teeth; anterior posterior one muscle smaller, oval; mantle line unindented, deepened, ventral margin denticulate. Mantle margin doubly fringed; excurrent opening with long, retractile process; foot long and pointed; oral lobes rudimentary; gills thick, folded. C. fimbriata (Linne). ? Few species, in the Indo-Australian region. Bathycorbis Iredale, 1930 Shell very small, triangular-oval, sculptured with concentric lamellae; lunule weakly depressed, narrow and short, valve with 2, indentation. Animal unknown. B. right umbo elevated; left with one main tooth; mantle line with a small despecta (Hedley), near Australia. This small species was Corbis; however Iredale appears to is less probable. first included in Chione, subsequently in place this species with the lucinids, which 1321 X. STIRPS ERYCINACEA ligament, sometimes as a rule small and thin, with internal Shell or completely covered by the mantle margin; posteriorly the partially mantle has only one opening; foot as a rule with a posterior byssal gland. 1. Animal on ERYCINIDAE Family laminae, the outer of which either side with 2 gill is narrower than the inner. A. Subfamily Erycininae Mantle margin in most cases with short papillae, but without groove-shaped prolonged and in Tellimya anteriorly often tentacles, forming a closed tube serving as an incurrent canal. Gonad hermaphroditic. Scacchia Philippi, 1844 umbo Shell transversely oval, thin, colorless, smooth; what posterior longish lateral the to right valve with pit; situated some- ligament small; cartilage in a external center; one main tooth, left with or 2 of these; 1 weak. Mantle lobes largely separate, posteriorly with one teeth opening; 2 gill laminae on either side; foot large, tongue-shaped; labial palps medium-sized. S. elliptica (Scacchi), in the Mediterranean Sea. Dall considered Scacchia as a subgenus of Erycina Lamarck, 1805 (synonyms Eryx Swainson, 1840; Neaeromya Gabb, 1873), the typical species of which, pellucida Lamarck, is fossil; also in the case of a few West Indian and Californian species only their relationship with Scacchia indistinct; cartilage situated in with 1 is the shells are uncertain. an oblique pit; The known, so external that ligament is hinge margin on either side or 2 small main teeth and 2 fairly long lateral teeth. Iredale, 1924, proposed a genus Melliteryx for the Australian E. acupuncta Hedley; the shell either side with is very small, exteriorally punctate, on one main tooth and anterior and posterior lateral tooth. Semierycina (Monterosato) Cossmann, 1911, also has on either side one main tooth and an anterior and posterior lateral tooth. E. (S.) Monterosato, in the Mediterranean Sea. found in E. bifurca (Webster) from New 1927, has proposed a group Arthritica. prismaticum Similar hinge teeth are also Zealand, for which Finlay, 1322 Bornia Philippi, 1836 870 more or transversely oval Shell triangular, in most cases shiny, sometimes somewhat folded; external ligament weak; cartilage posterior to the little umbo; short, a valve with a moderately long posterior left tooth and 2 shorter anterior ones; right valve with one anterior and 2 Mantle margin anteriorly broadened, with a longer posterior teeth. posterior opening; outer labial A gill lamina smaller than the inner one; foot long; palps small. few species, in Subgenus Bornia warmer s. s. seas. Mantle margin with short papillae, without long tentacles; byssal gland? B. (B.) corbuloides Philippi. Iredale, 1924, has proposed a genus Borniola for the Australian B. lepida Hedley. Subgenus Ceratobornia 1 1899. Dall, Mantle with 2 anterior and posterior long tentacles, in the greatly extensible posterior end of the foot with a byssal gland. B. (C.) longipes (Stimpson). Kellya Turton, 1822 (Kellia) Synonyms Lasaea (Leach) T. Brown, 1827; Cycladina Cantraine, Anapa Gray, 1847; Autonoe Leach, 1852. 1835; Poronia Recluz, 1843; Shell small, transversely oval, inflated; posterior to the center; umbo roundish, situated ligament with large cartilage attached on the underside of the hinge margin; hinge teeth fairly variable, as a rule on either side with one small tooth below the umbones and on the anterior and one posterior lamella, corresponding to are 2 anterior and posterior lamellae each. produced into a groove, which foot, posteriorly gill one left which on the right Mantle margin anteriorly continuous with the opening for the is with a very short siphon; foot long, with byssus; outer lamina narrow, without ascending lamella; labial palps narrow; viviparous. K. rubra (Montagu). Few species, in various seas. Tellimya T. Brown, 1827 Synonyms Chironia Deshayes, 1839; Oronthea Leach, 1852; Goodalliopsis Raincourt & Munier-Chalmas, 1863; Zoe Monterosato, 1878 (non Philippi, 1840). Shell roundish or transversely oval, smooth; elevated; ligamental cartilage internal; hinge teeth either side 1 or 2 main teeth and beset with papillae, 1 largely fused umbo only slightly somewhat variable, on or 2 posterior teeth. Mantle margins with one another and anteriorly — 1323 forming a tube serving as the incurrent canal, posteriorly with a short siphon; foot long, with byssus labial palps triangular; laminae not viviparous. folded; A gill few species, Tellimya Section various seas. in s. s. Shell roundish, and 2 posterior teeth on either T. (T.) ligament external of which are shorter and side, the anterior are sometimes fused above. Section Mancikellia Dall, inflated; development with 2 anterior rudimentary; cartilage strong; hinge in full suborbicularis (Montagu). 1899. Shell small, roundish; right valve with a small main tooth; anterior and posterior lateral tooth elongated; valve with a pumila (S. weak or rudimentary Wood). — left anterior and posterior lamella. T. (M.) Section Kelliola Dall, posteriorly shortened, posterior to the and a strong anterior tooth on either 1899. Shell small, longish, umbones with side. T. a strong cartilage symmetros (K.) (Jeffreys). Diplodontina Stempell, 1899 (tumbesiana Stempell, from Chile) Tellimya. This genus has been scarcely different from known in is most cases as Kellia Turton; however, the typical species, the latter designated is Cardium rubrum Montagu, synonym of Lasaea Leach. by Herrmannsen, ? Shell somewhat shell; thick, so that it becomes a Sphaerumbonella Coen, 1933 trapeze-shaped, greenish; bulging, oval anterior to the center, with a hemispherical, umbo situated smooth embryonic ligament internal; hinge margin without main teeth, on either side with one anterior and posterior lateral tooth. Animal unknown. S. brunellii Coen, ? Shell cartilage short in the Indian Ocean, near Massaua. Thecodonta A. Adams, 1864 longish oval; umbo close to the ligamental anterior end; with a triangular ridge, anterior to which on the lamella, posterior to it with a long, continuation of which another lamella is left narrow lamella, present; right valve in is a the and animal unknown. T. ? Adams, near Japan. Dall, 1899 (synonyms 1794) = Prisdphora Carpenter, sieboldi A. Subgenus Serridens (non Latham, Pristes Carpenter, 1864 1866, non Blanchard, 1835). Shell similar to Thecodonta, but cartilage without ridge; posterior lamella simple and teeth finely transversely striated. ter), near California. S. oblongus (Carpen- 1324 B. Subfamily Leptoninae Shell covered; ligamental cartilage short and thick; left valve with and a small anterior anterior and posterior lamella denticle, which is sometimes continuous with the lamella; right valve anteriorly and posteriorly with a couple of lamellae. Mantle anteriorly and posteriorly open, at the margins with more or less numerous tactile threads and at the anterior and posterior junction of the two lobes, each bearing a longer tentacle; on either side 2 smooth laminae; foot with a creeping sole gill and a posterior byssal gland; sexes separate (Fig. 827). Fig. 827. a, Lepton sp., seen from the left, after removal of the anus; aa, ap, anterior and posterior adductor muscle; f, left mantle lobe, foot; k, gill; margin (partly fused ventrally with that of the opposite p, labial palps; pp, attachment of the protractor of the foot; m, mantle side); n, kidney; rp, rp, retractor of the foot (after Pelseneer). Lepton Turton, 1822 Synonym Eupoleme Leach, Shell colorless, 1852. roundish or oval or somewhat triangular, in most cases thin and only slightly bulging, smooth or rough; umbo small, close to the center. L. squamosum (Montagu). A few species, in various seas. C. Subfamily Galeommatinae Shell in by the most cases ventrally gaping and often more or less covered which is beset with a few small warts; reflected mantle margin, the shell in most cases is elongated, with internal ligamental cartilage; 1325 hinge teeth variable. The mantle anteriorly and posteriorly has a tentacle; 872 anteriorly gill it is open and posteriorly has a fairly small opening; 2 smooth laminae on either side; foot with small byssal gland situated in the posterior part; sexes separate. Pythina Hinds, 1844 Shell not gaping and not covered distinct periostracum, in by the mantle margin, but by a most cases with fine radial sculpture, trapezoi- somewhat concave lower margin; hinge and weak lateral teeth. The interpretation dal or triangular, with straight or margin with 2 main teeth of the main teeth is (?) not clear, probably only an anterior tooth considered as such. The not reflected mantle margin anterior opening wide; papillae; foot with is posterior furrow short be to is beset with and small byssal gland. Section Pseudophythina P. Fischer, rays; shell only with weak lines; 1878. Periostracum with scaly both valves with 2 main teeth and a macandrewi (P. The animal is similar to posterior tooth. P. (P.) Ocean, near this growth Portugal. group belongs neither Bornia nor to to Fischer), in the Atlantic that of Pythina, therefore Tellimya, but — s. s. Both valves have a strong on the 2, also has are present a small, short lamella and posteriorly on the right left on the first it by Pelseneer. Section Phythina anterior main tooth, anterior to which similarity with a Lepton-species studied left one lamella. P. the Indo-Pacific region. ticed; hinge — (P.) deshayesiana Hinds. Section Rochefortula Finlay, Few species, in 1927. Shell lat- margin on one side with an anterior and posterior tooth, on the other side with longer lamellae. P. (/?.) reniformis (Suter), near New Zealand. Also belonging here are perhaps "Rochefortia" excellens and viastellata Hedley, for which Iredale, 1929, proposed the genera Barrimysia and Fastimysia. Myllita Orbigny & Recluz, 1850 Shell colorless, transversely oval, only slightly bulging, with strong folds diverging in the center; ligamental cartilage in an oblique pit; right valve with a small main tooth and the and a posterior lamella on the M. deshayesii (Orbigny Australia and for the New right & left with 2 of these; an anterior and 2 each of these on the Recluz) (Fig. 828). Few left. species, near Zealand. Finlay, 1927, proposed a "genus" Zemyllita more elongated New Zealand M. stowei (Hutton); further for roundish, small species, the sculpture of which has greater similarity with Divaricella, a genus Myllitella; genotype M. vivens Finlay. 1326 / 828. Interior and exterior sides of a shell valve of Myllita deshayesii Fig. (Orbigny & Recluz). Solecardia Conrad, 1849 Shell thin, in oval; umbo most cases smooth and and with an oblique Shell shiny, more or less elongated only slightly projecting, close to the center; ligament external more or internal cartilage; hinge often only weakly developed. covered by the mantle margin, which less extensively is sometimes smooth, sometimes beset with small warts, sometimes also 873 with longer threads, anteriorly and posteriorly with an unpaired tentacle; foot large, with small posterior byssal gland. Several species, in warm seas. Subgenus Solecardia s. s. Shell not gaping; left valve with an anterior and posterior lamella, corresponding to which are 2 each in the right valve; more or surface Barclayia H. Adams, 1874, Subgenus on the most cases on the right with posterior lamellae. S. Lionelita Jousseaume, eburnea Conrad. (S.) left more or less gaping; with 2 anterior and or 2 short anterior and 1 1, philippinensis (Deshayes). (S.) 1 S. scarcely different. Scintilla Deshayes, 1855. Shell teeth weak, in lamella, punctate. less is may be synonymous; 888, Iredale, seldom in Varotoga Iredale, 1931 at {S. 1 93 1 tooth, the right Zealand. proposed , is said to cryptozoica Hedley), has a few small warts Finlay, S. at the margin. 1927. Hinge on either side with one one hook-shaped, the mantle margin very narrow. weak and both ends and a smooth mantle, whereas on the reflected mantle and longer threads Subgenus Scintillona 2, Scintillula a genus Lactemiles for S. strangei (Deshayes); the animal possess siphonal processes hinge posterior 1 (S.) left one broadly triangular; reflected zelandica (N. Odhner), near New 1327 Subgenus Scintillorbis Dall, 1899. Shell small, roundish, very thin, transparent, with concentric rings and regular fine radial ligament rudimentary; hinge margin on the right with 2 denticles. 1, striae; external on the left with (5.) crispata (P. Fischer), near France. 5". Subgenus Divariscintilla Powell, 1932. Shell small, very thin, transparent; umbo situated anterior to the center; ventral margin with an angular indentation in the center; right valve with a denticle anterior to the ligament; valve toothless. 5. (D.) maoria (Powell), near left New Zealand. Vasconiella Dall, 1899 small; Shell indentation, to umbo close to the center; ventral margin with deep which a fold descends; hinge margin with a sharp tooth; ligamental cartilage small and short, without external ligament. V. jeffreysiana (P. Fischer), near Portugal. Galeomma Synonyms Parthenope Turton, 1825 Scacchi, Shell longish, ventrally gaping; cartilage in a median pit; 1833; umbo Thyreopsis H. Adams, 1868. scarcely projecting; ligamental hinge weak, often toothless. The mantle below forms a fold surrounding the foot and a covering on the surface of the shell; A foot with small posterior byssal gland. few species, in various seas. Subgenus Galeomma s. s. Shell bulging, laterally enclosing the body. Section Amphilepida Dall, 1899. Shell moderately gaping, without radial scultpure; hinge margin on either side of the cartilage with a small tooth-shaped process. G. (A.) politum Deshayes. s. G. — Section Galeomma s. Shell with radial sculpture, moderately gaping; hinge margin toothless. (G.) turtoni Lepirodes Broderip. P. Fischer, — Section Paralepida Dall, 1899 (synonym 1887, non Lepyrodes Guenee, 1854). Shell widely gaping, with fine radial sculpture; hinge margin anterior and posterior to the cartilage with a tooth-shaped process. G. (P.) Subgenus Libratula Pease, 1865. Shell flat formosum Deshayes. and smooth; both valves horizontal; hinge margin finely denticulate G. (L.) planum (Pease). Levanderia Sturany, 1905 Both valves shaped L. lines; flatly broadened, long and narrow, exteriorly with zig-zag- hinge toothless. erythraeensis Sturany, in the Red Sea. 1328 Ephippodonta Tate, 1889 Both valves lying in one plane, together circular, in the typical species with marginal teeth, which continue ray-shaped toward the center, and on the dorsal side with small cone-shaped elevations; in another species (lunata Tate) without marginal teeth and papillae; the very straight hinge margin on one side has an anterior and a posterior denticle; corresponding sockets on the other a small anterior and median part, the shell side. is With the exception of enclosed by the mantle margin beset with small warts; below the mantle has an opening for the foot and posteriorly an excurrent opening; foot with byssal gland; sexes separate. E. A macdougalli Tate (Fig. 829). ;-~:^iai-. Fig. 829. Inner side of the shell couple of Australian species. , ''.; i of Ephippodonta macdougalli Tate. Length 9 mm. D. Subfamily Chlamydoconchinae Shell completely enclosed pointed, posteriorly blunt; by mantle, long and narrow, umbo ligamental cartilage weak; no hinge. animal is thick, anteriorly roundish, close to the posterior end; The mantle covering the shell and with a small anterior and posterior opening; anterior mantle margin broadened similar to that in Bornia; adductor muscles completely absent; 2 gill laminae on either side; labial palps triangular; sexes separate. Chlamydoconcha Characters of the subfamily. C. orcutti Dall, near California. Dall, 1884 1329 MONTACUTIDAE Family 2. by the Shell anteriorly longer than posteriorly, external or covered mantle margin; mantle with an anterior and a posterior opening, on either side with only one phroditic; lamina. Foot with byssal gland; gonad herma- gill development often with brood care. Living in most cases commensally with sipunculids or echinoderms. 1909 Litigiella Monterosato, Shell oval, anteriorly longer than posteriorly; external ligament very weak, internal one strong; hinge margin on either side with a small main tooth and 2 elongated lamellae. glabra L. Lamy, near near France, on Sipunculus, and L. Fischer), (P. buryi Brazil. Mysella Angas, 1877 Synonym Shell Rochefortia Velain, external, cases smooth; 1878. transversely oval umbo more somewhat or angulate, in most or less close to the posterior margin; external ligament weak; cartilage short, situated below the umbones, anterior and 875 posterior to it less distinct one valve has an oblique tooth, above which the more or expansions of the other valve are connecting. M. anomala Angas. Several species, Sometimes only the Malvinasia J. E. Cooper & anterior tooth Subgenus Rochefortina Dall, is and concentric; both valves with 2 Subgenus Sphenalia umbo nearly terminal; left S. developed, as also in J. E. Cooper & Preston, scarcely different from Mysella. 1924. Shell very small, oval; situated nearly in the center, with small ? well Preston, 1910 (arthuri near the Falkland Islands), which ? various seas. in is embryonic denticles. R. Wood, 1874. umbo shell; sculpture radial semele Dall, from Oahu. Shell somewhat angular; valve with 2 very small teeth; right valve with 2 small expansions of the hinge margin. S. donacina S. Wood, near England. ? margin Subgenus Pythinella straight; Dall, 1899. Shell elongated triangular; lower right valve with 2 teeth. P. cuneata (Verrill & Bush), near North Carolina; commensal with crustaceans. Montacuta Turton, 1822 Shell external, oval, anteriorly in smooth or with a few narrow most cases longer than radial ribs, transversely posteriorly; external ligament 1330 weak, the internal one anterior to on it in most cases on ridges posterior either side with a end bears a more or to the narrow lamella, which umbones, at the posterior less distinct tooth. Several species, in various seas. Section Montacuta very small substriata and thin, (Montagu) s. s. (synonym Coriareus Hedley, 1907). Shell with a few thread-shaped radial (Fig. 830). 1875. Ligamental ridges absent; — (Jeffreys). — left Section Decipula ribs. M. (M.) (Jeffreys) M. valve without tooth. Friele, (D.) ovata Section Orobitella Dall, 1900. Attachment of the ligament elevated; teeth without lamellae. Fig. M. (O.) floridana Dall. 830. Montacuta substriata (Montagu), (after Sars). Subgenus Aligena H.C. Lea, 1845 (synonyms Spaniodon Reuss, ? 1867; Laubriereia Cossmann, 1887; Kelliopsis Verrill & Bush, 1898) is not distinctly different from Montacuta; ligament with a calcareous part; the anterior teeth may become rudimentary A. striata Lea f; few living species described from the American coasts; Montacuta salamensis Jaeckel & Thiele, from East Africa, probably also belongs here. Asbjornsenia Friele, 1886 {striata Friele) identical is presumably related or with Montacuta ferruginosa (Montagu). According to Lamy, Issina Jousseaume, 1898 (issina Jousseaume, from the Red Sea), probably = Montacuta. is Benthoquetia Iredale, 1930 Synonyms Austroturquetia Cotton, 1930; Isoconcha (Pelseneer) Prashad, 1932. Shell external, transversely oval, umbo somewhat compressed in the center; close to the center, only slightly projecting; ligament only external; hinge margin on either side with one tooth. Mantle with a posterior opening, which is separated by a long suture from the anterior opening, which forms an incomplete incurrent tube by means of folds; 876 foot with strong byssus; the single within it. gill lamina is smooth; the eggs are stored 1331 B. Integra (Hedley), near Australia. Pelseneer, 1911, described the animal of Isoconcha sibogai, but not the shell, which this Australian was first described by Prashad in 1932, in whose opinion species belongs to the same genus as Hedley's species. This genus differs from other montacutids by the completely external ligament. ? Turqetia Velain, 1 876 Shell small, posteriorly truncated; ligament external, situated posterior to the tooth. T. umbones; hinge margin on side either with tubercle-shaped a Animal unknown. fragilis Velain, near the islands of St. Paul and Amsterdam. Jousseaumiella Bourne, 1907 Synonym Jousseaumia Bourne, 1906, non Sacco, Shell small, triangular, anteriorly 1894. somewhat longer than internal ligament moderately long; right valve with posteriorly; one tooth, which is valve; on the left with an elongated clasped by 2 lamellae of the left anterior and posterior lateral tooth. Mantle widely open, with smooth margins; foot with small byssus. J. heterocyathi (Bourne). species 2 in the Indian Ocean, on Heterocyathus and Heteropsammia. Devonia Winckworth, 1930 Synonym Synapticola Malard, Shell external, thin, oval or to posterior end; hinge ?; 1892. angulate, gaping; umbo close mantle margin with large papillae, with an anterior and a posterior opening; shell margin; the posterior part brood chamber; foot 1903, non Voigt, somewhat it forms a narrow covering over the of the mantle cavity forms a bell-shaped large, with a sucker-shaped depression; labial palps absent. D. perrieri (Malard), on Leptosynapta inhaerens, near France; another species, D. semperi (Ohshima), on Protankyra bidentata, near Japan. Entovalva Voltzkow, 1890 Shell oval, smooth; umbo close to the posterior end; mantle larger than the shell, completely enclosing it; its posterior bell-shaped part 1332 forms a large brood chamber, otherwise the animal similar to that in is Devonia. mirabilis E. Voltzkow, in the esophagus of Patinapta crosslandi Heding, near Zanzibar. Cycladoconcha Sparck, 1932, may be shell is lost except for ring-shaped parts teeth; foot and siphon considered as a subgenus; the of the valves, with small hinge large; gills small. C. amboinensis Sparck, in the esophagus of Patinapta laevis (Bedford). Scioberetia Bernard, 1895 Shell oval, radially ribbed; internal; umbo close to the posterior end; ligament hinge margin toothless. Adductor and foot musculature weak; foot small, with groove-shaped sole; mouth surrounded by narrow the mantle completely encloses the shell; its its margin is posterior part serves as a brood space; the excurrent opening S. australis Bernard, XI. 877 on spatangids, near Tierra margin small. more or less inequivalve; ligament with few teeth; mantle line unindented. fairly thick, The bivalves belonging here are largely extinct; evolved very peculiarly, so that they have bivalves; their is del Fuego. CHAMACEA STIRPS Shell with one valve cemented, variable; hinge lips; anteriorly broadened; two valves are very different little the rudists have similarity with normal and are not joined with one another by a ligament. 1. Family CHAMIDAE Shell irregularly formed, thick, exteriorly with divided, sometimes distinctly elongated lamellae or spines, often vividly colored; the cemented, in most cases left, valve larger and deeper than the other one, both distinctly spiral; ligament external, on short, thick ridges, anteriorly cleft; hinge margin thick, on the right with a lower, sometimes disappearing tooth and an arch-shaped main tooth, between which on the a somewhat arch-shaped tooth, whereas an upper tooth is left catches only weakly developed in the posterior part; a posterior lateral tooth is indicated on both sides; muscle scars large, elongated oval. Mantle margin with numerous tentacles; the incurrent opening ventral between that for the foot and the excurrent opening; gill laminae folded, the exterior one narrow; foot fairly small, without byssus; labial palps small; kidneys sack-shaped, connected with one another; pericardial limb fairly long. 1333 Chama Synonyms Globus Modeer, 1793; 1789 (Linne, 1758) Bruguiere, Klein, 1753; Jataronus Adanson; Psilopus + Psilopoderma Poli, 1757; Maceris 1795; Lacinia Mus. Calonn., 1797; Planospirites Lamarck, 1801; Macerophyllum (Meuschen) Herrmannsen 1 847. Characters of the family. A few species, in warm seas. Subgenus Echinochama P. 1887 (synonym Arcinella Fischer, Schumacher, 1817, non Oken, 1815). Shell fairly regular and equivalve, with radial rows of spines, cemented by the right valve in most cases only in the young; embryonic lunule distinctly delimited; shell equivalve, with concentric ribs. C. (£.) arcinella Linne, near the Indies, and californica Subgenus Chama West Dall. s. s. Shell permanently cemented by one, in irregular, distinctly most cases, the lunule. C.(C.) lazarus Linne (Fig. 831). for C. cristella large, left inequivalve, valve, without Pseudochama N. Odhner, 1917, Lamarck, cemented by the right valve, is not recognized by Lamy. Fig. 83 1 . Inner side of the right shell valve of Chama lazarus Linne. Length about 9 cm. XII. STIRPS CARDIACEA Shell of highly variable size, in most cases with radial sculpture, equivalve; ligament external; main teeth in most cases cone-shaped, on the right without central tooth; lateral teeth 878 seldom the hinge teeth are reduced. Mantle away from line in the main teeth, most cases unindented; 1334 siphons short as a rule; in tridacnids the anterior adductor muscle reduced; gill 1. Family Shell variable in size, in distinctly longer than broad, edge is is laminae folded. developed, which is CARDIIDAE most cases roundish or more oval, occasionally often higher than long, frequently an sometimes very high; seldom lacking more or less strong radial ribs, which are frequently beset with transverse scales or spines; the periostracum is most cases weak; the external in ligament short and strong; as a rule 2 main teeth on either side, the median of which are stronger than the outer ones, and anterior and posterior lateral teeth; the anterior one often arising from the depression of the umbones. Mantle margin with papillae or smooth; incurrent and excurrent siphons fairly short, with the exception of Adacna, with tentacles, which sometimes contain eyes; the lower siphon is not separated from the anterior opening in a few groups, in which the mantle suture has a large valve, which extends gills; gill below the posterior end of the laminae folded, with large inner marginal filaments; outer laminae narrow, separated from the inner ones by a more or less large internal, below which runs the vas efferens; the septum broad beside and posterior to the foot, occasionally with a few folds; foot strong, long, bent; byssus occasionally rudimentary; labial palps fairly long, triangular; the sexes are seldom separate, in most cases hermaphroditic. Microcardium n. gen. Shell small and thin, translucent, inflated, only slightly longer than numerous thread-shaped radial ribs, the intervening spaces of which show dense lamellae, and on which there are more to less numerous radial rows of pointed small projecting scales; at the ends of high, with the ribs the margin is sharply denticulate; umbo projecting, situated nearly in the center; anterior margin curved; posterior most cases somewhat flattened; rounded, margin in ligament weak, on either side 2 main teeth, lateral teeth placed fairly far away, the left posterior one represents a narrow expansion of the hinge margin. Animal unknown. M. torresi (Edg. Smith), distributed placed this species in Fragum, which named later a similar West Indian species Protocardia ? , is in the Indian Ocean. Smith hardly acceptable, whereas Dall first Cardium (Fulvia) peramabilis, which again cannot be accepted. Dall mentions a few similar Tertiary species. 1335 Nemocardium Meek, 1876 which are spiny, warty, Shell fairly small, with densely placed ribs, or lattice-shaped on the posterior part. N. semiasperum (Deshayes) |- Grant and Gale placed the Califomian species centifilosum (Carpenter) here, in which the posterior part, delimited by a weak edge, has a few concentric lamellae; the margin because of the Protocardia is denticulate considered Nemocardium as a section of Dall ribs. whereas Grant and Gale subordinated Beyrich, under it Laevicardium; both of these propositions appear unacceptable; the above- mentioned living species most closely is with Pratulum and related Lophocardium. Pratulum Iredale, 1924 Shell fairly thin, medium-sized, transversely oval, posteriorly a gaping; surface with numerous narrow radial posterior of which are somewhat tuberculate; delimited by a somewhat stronger rib; denticulate; away from lateral teeth fairly far ribs, margin the little anterior and the posterior part at is the ends of the ribs the main teeth. Animal unknown. P. thetidis (Hedley). A couple of species, near Australia and New Zealand. Lophocardium Shell thin, transversely oval, P. 1887 Fischer, somewhat gaping, very by an elevated lamella; animal shows distinct anatomical thin septum, which anteriorly posteriorly finely latticed, posterior part wrinkled, delimited lateral teeth reduced. Dall states that the differences, of which he mentions a extends to beside the foot. L. cumingi (Broderip), in Central America. Laevicardium Swainson, 1840 Synonym Liocardium Morch, Shell of variable, distinctly ribbed; margin more or umbo less 1853. sometimes considerable, size, strong, in most cases elevated; outline roundish without edge; hinge curved, with distinctly developed teeth; posterior margins not gaping; genitalia hermaphroditic. Subgenus Discors Deshayes, 1858 (synonyms Lyrocardium Meek, 1876; Amphicardium Martens, 1880; Divaricardium Dollfus & 1336 Dautzenberg, periostracum; roundish, Shell 1886). with distinct red or speckled with weak ribs and sharp oblique ridges; anterior part posterior part with distinct radial ribs; lower margin denticulate. L. (D.) subdiscors (Orbigny) f , few living species, near the Philippines and near San Thome. Subgenus Laevicardium s. s. Shell moderately strong, in most cases higher than long, sometimes somewhat triangular, exterior sculpture weak, with distinct periostracum; hinge margin arched; ventral margin A norvegicum (Spengler). interiorly denticulate. L. (L.) few species, in various seas. Subgenus Vasticardium umbo Iredale, 1927. Shell large, higher than long; elevated; surface with smooth, flat, dense ribs. L. (V.) nebulosum (Martyn), in the Pacific Ocean. Subgenus Mexicardia Steward, 1930. Shell large, higher than long, with very strong umbones; surface with broad, separated by deep furrows. L. rib-like flat, folds (M.) procerum (Sowerby), near Central America. Subgenus Dinocardium ventricose, Dall, 1900. Shell large, obliquely triangular, somewhat posteriorly umbo flattened; large; strong, flattened ribs, scaly in the anterior part. L. (D.) in the surface with magnum (Born), Gulf of Mexico. Subgenus Vepricardium Iredale, 1929. Shell medium-sized, round- with rounded ribs which are beset with short thorns L. (V.) ish, pulchricostatum (Iredale), near Australia. Subgenus Trachycardium Morch, 1853. Shell ventricose, higher than somewhat obliquely oval, with ribs bearing scales, the intervening long, spaces of which are finely transversely striated or granulose. L. (T.) isocardia (Linne). A few species, in warm seas. Papyridea Swainson, 1840 880 Shell compressed, longer than high; surface with numerous, short, more or closer to the anterior end; borne on ridges; hinge margin weakly curved. Few species, in warm Section Papyridea s. distinctly longer than high; ends of the Shell umbo less scaly or spiny ribs, gaping; ligament ribs. P. (P.) seas. s. Shell thin, fairly gaping at both ends, posterior margin sharply denticulate at the — spinosa (Meuschen). Section Fulvia Gray, 1853. very thin, roundish, posteriorly gaping, with fine radial threads; anterior part finely warty; posterior margin not denticulate. P. (F.) aperta (Bruguiere). 1337 Serripes (Beck) Gould, 1841 Synonyms Aphrodite Lea, 1834, non Hiibner, 1816; 1789, nee Lamarck, 1840, non Bruguiere, Shell large, longer than high, triangular, with only at the ends; posteriorly main straight, Acardo Swainson, 1801. weak radial sculpture reduced; lateral teeth weak; teeth mantle line compressed, ventrally cuspidate; genitalia foot hermaphroditic. S. groenlandicus (Gmelin). 2 Nordic species. Cardium Linne, 1758 Synonyms Cordium Gistel, 1848; Eucardium P. Fischer, 1887. Shell roundish or somewhat elongated, with rib-like folds which umbo often tuberculate or spiny; are projecting, close to the center; hinge margin only slightly curved, with main and lateral teeth. Several species, in various seas. Subgenus Cerastoderma than high; ribs 1795) Morch, 1853 (synonym Cerastes (Poli, 1768). Shell in most cases 1795, non Laurenti, Poli, often beset with tubercles, warts, somewhat longer Section or spines. Parvicardium Monterosato, 1884. Shell small, somewhat longish; folds anteriorly and posteriorly warty. C. Cerastoderma s. tubercles. (C.) C. s. parvum (P.) Philippi. — radial Section Shell larger, longer than high; radial folds with edule Linne. —Section weak Rudicardium Monterosato, folds high, somewhat warty; 1917. Shell roundish, medium-sized; radial intervening spaces with transverse wrinkles. C. (R.) tuberculatum Linne. — Section E. Acanthocardia Gray, Romer, 1869). Shell intervening spaces and large (synonym Acanthocardium 1851 fairly thin; rib-like folds warty or spiny; with dense transverse ridges. fairly broad, C. (A.) aculeatum Linne. Subgenus Cardium (synonym Tropidocardium E. Romer, 1869). somewhat longer than high, posteriorly broad and flat, with sharp keels or thorns or scales; s. s. Shell large, fairly thin, inflated, gaping; rib-like folds intervening spaces broad; lateral 832). 2 species, near (Fig. Subgenus Ringicardium posteriorly gaping; tuberculate P. rib-like or wrinkled; teeth Fischer, folds flat; Africa. C. C. (C) costatum Linne Africa. 1887. Shell strong, roundish, posterior intervening posterior ribs margins, separated by deep incisions. West thin. West and North with (R.) leaf-shaped spaces elevated ringens Chemnitz, near 1338 880 Fig. 832. Inner side of the right shell valve of Cardium costatum Linne. Length about 9 cm. Corculum (Bolten) Roding, 1798 Synonym Hemicardium (Cuvier) Schweigger, 1820. more or Shell higher than long, inclined, ribbed, with a edge descending from the umbones; hinge margin less sharp fairly short, curved. Incurrent opening of the mantle not separated from the opening for the hermaphroditic. genitalia foot; Subgenus Afrocardium Tomlin, 1930. Shell fairly small, inclined, with rounded edge and several narrow, scaly ribs. C. (A.) shepstonense (Tomlin). A few species, in the Indian Ocean. Subgenus Papillicardium Sacco, 1899. Shell somewhat like folds, inclined, with weak, intervening spaces of which the striated. C. (P.) papillosum Ocean. This group guppyi Thiele is is (Poli), in the are rib- regularly transversely West Indian Cardium intermediate between the typical species of the two. Dall, 1900. Shell fairly small, strong, with strong, tuberculate ribs, the intervening spaces transverse ridges; posterior part C. (T.) graniferum (Broderip & Subgenus Ctenocardia H. thorny roundish, Mediterranean Sea and Atlantic close to Trigoniocardia; the Subgenus Trigoniocardia few fairly small, rounded edge and several tuberculate ribs; posterior part somewhat Sowerby). & Few A. Adams, with dense ribs, of which have dense flattened, with weaker ribs. Central American species. 1857. Shell with several which bear only small scales. C. (C.) hystrix (Reeve), near the Philippines. Subgenus Fragum (Bolten) Roding, 1798 (synonym Loxocardium Cossmann, 1887). Shell strong; posterior part delimited by a blunt edge, 1339 with strong, tuberculate or scaly rib-like folds; intervening spaces smooth; margin denticulate. C. unedo (Linne). Few species, (F.) in warm Subgenus Hemicardia (Klein) Morch, 1853. Shell with a seas. keel-like edge, which ventrally forms an acute angle; ribs fairly broad and the sides flat, on of the body with tubercles; intervening spaces narrow, with dense transverse ridges. C. hemicardium (Linne), (//.) in the Indian Ocean. Subgenus Lunulicardia Gray, 1853 (synonym Opisocardium Bayle, 1879). Shell similar to Hemicardia, but with a deeply sunken C. (L.) retuswn (Linne). Subgenus Corculum A s. couple of species, in the lunule. Indian Ocean. (synonym Cardissa Megerle von Muhlfeld, s. 1811). Shell thin, greatly shortened and laterally broadened, with a very high keel, without lunule, although with a small smooth area on the posterior side; tuberculate A in with surface the upper couple of species, Fig. in flat part. C. the Indian rib-like (C.) folds which are somewhat cardissa (Linne) (Fig. 833). Ocean and near Central America. 833. Shell of Corculum cardissa (Linne). Didacna Eichwald, 1838 Shell longer than broad, in most cases with a posterior edge, more or less strongly ribbed; lateral teeth rudimentary; either side; mantle line not or or 2 main teeth on weakly indented. Mantle with 2 posterior 1 openings, which form short siphons beset with papillae. A few species in the Subgenus Didacna s. Caspian Sea. s. Shell with posterior edge, posteriorly not gaping; hinge with 2 main teeth on either side, without mantle sinus. D. (D.) trigonoides (Pallas). 1340 Subgenus Monodacna Eichwald, 1838. Shell transversely oval, with- out edge, posteriorly gaping; hinge with one main tooth on either side, with small mantle sinus. D. (M) caspia (Eichwald). Adacna Eichwald, 1838 Synonyms Hypania (Pander) Kupffer, 1831; Hypanis (Pander) Menetries, 1832 (non Boisduval, 1833); Hypnaxis Gray, 1847. Shell thin, laterally compressed, longish, anteriorly and posteriorly more or gaping, with teeth; without distinct hinge less distinct rib-like folds, mantle line deeply indented. Mantle with long siphons which are fused with one another, their ends bearing small warts; foot fairly short, compressed. A. laeviuscula Eichwald. 2. Shell thick, large, Few Family in species, in the Caspian Sea. TRIDACNIDAE some cases gigantic, with radial sculpture; anterior part of the hinge margin reduced, so that only one and the posterior margin is is peculiarly twisted, so that the mantle opening for the foot upwardly directed; the incurrent opening lower side, and the excurrent opening lies at lies the anterior part of the in the posterior to which is the anterior center; adductor muscle absent, whereas the posterior one center, main tooth ligament external, the anterior obliquely upwardly directed, in most cases interiorly denticulate. The animal is lateral tooth are present; in lies about the the attachment of the foot retractor; gill laminae fairly narrow, folded; gonads hermaphroditic. The Tridacnidae connect with Byssocardium Munier-Chalmas, the cardiids through the fossil genus 1882. Tridacna Bruguiere, 1789 Shell very large and thick, longish triangular, with radial ribs strong scaly folds, upwardly directed anterior margin gapes just anterior is interiorly denticulate; the hinge is to is margin on either side has one main tooth and one posterior lateral tooth on the main tooth and wavy; the the umbones; it through which the tower margin left, 2 on the right; below the the sunken attachment of the anterior foot muscle. mantle margin bears numerous warts; the excurrent opening is small foot has a strongly developed byssus; labial palps narrow; The small; the gill folds high; posterior foot retractor strong. T. gigas (Linne). Few species, in the Indo-Pacific region; they attach their byssus to stones or live in corals. 1341 Hippopus Lamarck, 1799 Synonym Cerceis Gistel, 1848. Shell similar to Tridacna, although without gaping opening; anterior end flattened and delimited by an edge. Foot posterior retractors larger, without byssus; small. H. maculatus Lamarck (Fig. 834), in the Indo-Pacific region, living in sand. Fig. 834. Inner side of the left shell valve of Hippopus maculatus Lamarck. Length about 11.5 cm. XIII. Shell in most cases STIRPS strong, VENERACEA smooth or sculptured, transversely oval or triangular, equivalve; right valve with central tooth and an anterior and posterior main tooth, catching between which are the teeth of the valve; an anterior lateral tooth of the left valve is absent; adductor muscle scars nearly symmetrical; a mantle sinus or less developed, seldom completely absent. left often rudimentary or The mantle in is more most cases widely open below, and posteriorly has sometimes shorter, sometimes longer, siphon fringed at the ends which are in most cases partly fused with one another; their partition wall often has a valve; folded; foot in gill laminae most cases without byssus. 1. Family VENERIDAE Shell regularly formed, not gaping, often with a lunule, which is more or less distinctly delimited; the left valve, in addition to the bilobed main tooth, has a posterior main tooth and in a few genera a more or less strong anterior accessory tooth, corresponding to which in the right valve 1342 is a socket with elevated margins. The mantle line in most cases it is seldom unindented, has an angular or rounded sinus, which is anteriorly or obliquely upwardly directed. A division of this family into subfamilies has been attempted, based mainly on the presence or absence of the anterior lateral tooth, which sometimes rudimentary; and through such a division some related forms would be separated from one another, therefore it does not however, seem to is be useful. It not certain whether different evolutionary lines is can be recognized. Gouldiopa Shell small, bulging, Iredale, somewhat 1924 slanting rounded-triangular, without sculpture; lunule only slightly deepened; in the right valve the anteriormost tooth is thin, the median somewhat triangular, the posteriormost large, longish, slanting, and cleft; in the left valve the thin, anterior main tooth and the stronger median one are joined above, the posteriormost very thin, and the anterior lateral tooth large and close to the anteriormost main tooth; mantle line fairly far from the margin, scarcely indented. G. australis (Angas), near Australia. Lioconcha Morch, 1853 Shell medium sized, strong, oval, with projecting umbones, smooth or with fine concentric sculpture; lunule only slightly deepened; hinge margin ally thick; right anterior weakly furrowed; left main tooth anterior small, the posterior one occasionmain tooth weak, the posterior one partly joined with the ligamental ridge; mantle line unindented; margin smooth. L. castrensis (Linne). ? Few species, in the Indo-Pacific Ocean. Granicorium Hedley, 1906 Shell roundish, posteriorly somewhat angulate. bulging; lunule deepened, although not delimited by a furrow; surface with concentric sculpture and with an attached cover of sand; hinge margin broad, on either side with 3 anterior one lateral G. is main median of which is triangular; the one furrowed, without anterior mantle sinus; inner margin smooth. teeth, the right short and the posterior tooth, without distinct indutum Hedley, near eastern Australia. 1343 Gouldia C. B. Adams, 1847 Shell fairly small, oval with somewhat elevated umbones; surface with concentric sculpture, at the ends sometimes finely radially striated; lunule shallow; hinge teeth broadly diverging; right posterior main tooth fur- rowed; left anterior lateral tooth separated from the anterior main tooth; mantle line weakly indented; margin smooth or somewhat rough; posterior dorsal margin furrowed. A G. cerina (C. B. Adams). few species, in various seas. Fluctiger Iredale, 1924 Shell small, strong, oval; umbo pointed, anteriorly inclined; lunule long and narrow; surface with a few wavy folds forming an angle in the center; hinge teeth similar to those in Circe. F. royanus Iredale. A couple of Australian species. Comus Shell umbo thick, thick, elevated; on the L.R. Cox, 1930 unequal-sided triangular, with broad concentric folds; lunule long and narrow; ligament short; hinge margin right with a posterior projecting main tooth joined with the ligamental ridge and a moderately developed median main tooth, whereas the anteriormost one is rudimentary; on the with a thin posterior one, left a very strong median one and a short anterior one, which touches the lateral tooth; mantle line unindented; margin interiorly finely denticulate. C. platyaulax (Tomlin), near South and East Africa. Gafrarium (Bolten) Roding, 1798 Shell roundish or transversely oval, strong, with concentric, some- long and narrow; hinge times also radial sculpture; margin broad, with tooth more or lunule 3 separate less long; main shallow, teeth on either side; anterior lateral mantle line not or weakly indented. Subgenus Circenita Jousseaume, 1888. Shell roundish, bulging, with concentric sculpture; main teeth fairly small and closely adjoining one another; anterior lateral tooth strong, short; mantle line weakly indented; margin smooth. G. (C) arabicum (Chemnitz). Few species, in the Red Sea. Subgenus Gafrarium s. s. (synonym Crista E. Romer, 1847). Shell transversely oval, moderately bulging, with radial, tuberculate ribs; hinge 1344 margin short; left median main tooth furrowed; mantle weakly line in- dented; margin often denticulate. G. (G.) pectinatum (Linne) (Fig. 835). 835. Shell of Gafrarium pectinatum (Linne). Fig. Length about 4 cm. Subgenus Circe Schumacher, 1817. Shell with flattened initial part; umbo angulate, lateral tooth fairly long and low; mantle line scarcely indented. only slightly projecting; hinge margin strong; anterior Section Circe s. s. Surface with concentric sculpture, often also with diverging ribs on the dorsal parts; median one species, in the Indian Ocean. diverging; (Chemnitz). Few posterior — main tooth long, the A few Section Parmulina Dall, 1902. wrinkled, the following with distinctly left margin smooth. G. (C.) scriptum (Linne). cleft; concentric margin weakly denticulate. G. species, in the Red Initial part hinge teeth large, sculpture; (P.) corrugatum Sea. Callocardia A. Adams, 1864 Shell very thin, hinge margin weak; anterior and posterior joined arch-shaped; formed of 2 narrow left posterior tooth long and free, main the right plates; anterior lateral tooth pointed, arising teeth one from the margin; mantle line unindented. C guttata A. Adams, in the northern Pacific Samarangia Shell Dall, Ocean. 1902 very strong, nearly colorless, roundly quadrangular, smooth; somewhat depressed; ligament sunken; hinge margin strong, on the left with a fairly long posterior main tooth, a very thick, somewhat divided median one, and, joined with it, a weak anterior main tooth, anterior to which lies a distinct wart-shaped lateral tooth; on the right the posterior tooth is strong, distinctly furrowed, the median one triangular, lunule the anterior one small, above a furrow with a minute pit corresponding to the anterior lateral tooth; the smooth. mantle line has no sinus; inner margin 1345 & quadrangularis (Adams S. Reeve), in the northern Pacific Ocean. This species appears to have been misidentified to date, as shown by the diagnosis of the genus and and is similar to that in is more its placement together with Venus exalbida of which are very different. The small lenticularis, both some Dosinia species, although lateral tooth seems it this group closely related with Callocardia and Pitaria. Pitaria E. Romer, 1857 (Pitar) Synonym Caryatis E. Romer, 1862, non Hiibner, 1816. Shell oval or rounded triangular, smooth or concentrically striated; lunule not deepened; hinge margin often with a groove-shaped depression below the right anterior main main tooth tooth; left posterior separated from the ligamental ridge or joined with it; partly anterior lateral tooth short. Subgenus Aphrodora Jukes-Browne, 1914 (synonym Leucothea JukesBrowne, 1913, non Rafinesque, 1815, nee Mertens, 1833). Shell margin colorless, concentrically striated; hinge narrowed; teeth weak, thin, short, curved, posteriorly posterior one short and marginal in position, left the right one joined arch-shaped; mantle sinus short and rounded. P. (A.) birtsi (Preston), in the Indian Ocean. Subgenus Tinctora Jukes-Browne, 1914 (synonyms Callizona JukesBrowne, 1913, non Doubleday, 1846; Callizonata Strand, 1928). Shell thick, roundish, shiny; one partly what rough. P. median main tooth very left thick, the posterior mantle sinus moderately deep, rounded; margin some- free; (T.) vulnerata (Broderip). Subgenus Pitaria s. Shell strong, rounded triangular or s. more oval. Section Pitarina Jukes-Browne, 1913. Right main teeth joined, the left posterior one free; ligamental ridges smooth; mantle sinus short, rounded. P. (P.) (Lamarck). citrina — Section Calpitaria Jukes-Browne, Right main teeth separate, the one partly free; left median one 1908. triangular, the posterior ligament ridges furrowed; mantle sinus short and rounded. P. (C.) sulcataria (Lamarck). main Shell colorless; tooth long and partly right — free, ligamental sharply angulate. P. (A.) texasiana (Dall). teeth separate, the left Section Agriopoma Dall, 1902. teeth joined arch-shaped; the left posterior median one — ridges smooth; mantle sinus Section Pitaria triangular, the posterior s. s. Right main one joined with the longitudinally furrowed ligamental ridge; mantle sinus deep and pointed. P. (P.) tumens (Gmelin). large, oval, — Section Megapitaria Grant smooth, hinge similar to that in Pitaria & s. s. Gale, 1931. Shell P. (M.) aurantiaca (Sowerby). Subgenus Amiantis Carpenter, 1863. Shell with concentric rings or lamellae, oval; lunule somewhat deepened; ligament long, superficial; — 1346 somewhat elongated; anterior lateral tooth left posterior main tooth long, fused with the ligamental ridge; right anterior main tooth short. Section 1902 (synonyms Dione Gray, Lamelliconcha Dall, 1847, non Hubner, 1816; Hysteroconcha (Lang, 1722) Dall, 1902). Shell with distinct posterior hinge margin posteriorly narrowed; longitudinally furrowed; sinus anteriorly rounded. large, Amiantis s. s. more or less edge which sometimes bears spines; ligamental ridges P. (synonym Eucallista concinna (Sowerby). (L.) Dall, mantle — Section 1902). Shell thick, with broad concentric rings; hinge strong; ligamental ridges wrinkled; mantle sinus most cases acutely angled. P. in (Conrad). (A.) callosa Subgenus Macrocallista Meek, 1876. Shell more or oval, smooth or with concentric furrows; lunule only most cases not anterior lateral tooth in far less elongated slightly deepened; from the main teeth; right in most cases without depression below the anterior main which close to the median one; on the tooth, on the left the two anterior main teeth are joined above, the posterior one continuous with the ligamental ridge; margin not denticulate. Section Notocallista Iredale, 1924. Shell oval, is only with growth lines; lunule indistinct; hinge similiar to that in Lamelliconcha; posterior right main tooth strong. P. (N.) kingi (Gray). — Section Paradione Dall, 1909 (synonyms Chione Gray, Megerle von Muhlfeld, 1811; Callista (Poli, Cossmann, 1886, non Swainson, 1840). Shell weak radial distinctly delineated; sometimes with shiny, socket for the strong anterior lateral tooth the striae; 1838, non 1791) Morch, 1853; Chionella posterior right main tooth slender; mantle sinus broad, anteriorly angulate. Considering that according to Dall and Jukes- Browne, Chionella, proposed for the Deshayes, is = Chione; Section Macrocallista 887 it s. fossil species Cytherea ovalina includes the group of Venus chione Linne. s. Shell considerably elongated, large; posterior main teeth long; mantle sinus fairly short. P. (M) nimbosa (Solander) = gigantea (Gmelin). Section Lepidocardia Dall, 1902. Shell fairly small, — shiny, posteriorly with concentric furrows, anteriorly rounded, posteriorly pointed; hinge margin short, with closely adjoining teeth. P. (L.) africana (Philippi) =floridella (Gray). — Section Transennella Dall, 1883. Shell small; mantle sinus rounded; margin longitudinally furrowed. P. (T.) conradina (Dall). Amiantis and Macrocallista are in most cases considered as genera, but their differences are only slight. Saxidomus Conrad, 1837 Shell posteriorly large and strong, elongated oval, with strong growth lines, somewhat gaping, without distinct lunule; ligament long; 1347 hinge margin fairly narrow, on the left with an oblique anterior lateral tooth and 3 slender closely adjoining main teeth, the posteriormost of which is separated from the ligamental ridge; on the right with 3 main teeth; mantle sinus deep; margin smooth. Siphons long. S. nuttalli Conrad. 3 species, in the northern Pacific Ocean. Sunetta Link, 1807 Synonyms Cuneus Megerle von Miihlfeld, 1811, non Da Costa, Meroe Schumacher, 1817. Shell more or less elongated oval, strong, smooth or concentrically 1778; sinus short, A few ligamental area deepened; hinge margin on lunule narrow; sculptured; either side with 3 main somewhat anterior lateral tooth fairly long; mantle teeth; margin denticulate. angular; and on the African west species, in the Indo-Pacific region coast. Section Sunetta s. Shell longish; left posterior s. main tooth short, the right one smooth. S. (S.) scripta (Linne). Sunettina L. Pfeiffer, 1869 (synonym Solanderina — Section Sunemeroe 1902) [solandri (Gray)] Dall, is more bulging. 1930 (synonym Sunettina Jousseaume, Iredale, 1891, non L. Pfeiffer, 1869). Shell roundish, compressed; posterior side longer than the anterior; one furrowed at the posterior left tip. S. main tooth long and thin, the right adelinae Angas. (5.) Meretrix Lamarck, 1799 Synonym Nympha Morch, Shell triangularly oval, concentrically sculptured; 1853, non Fitzinger, thick, in 1826. most cases smooth, sometimes lunule indistinct; ligament fairly short, on greatly projecting, wrinkled ridges; hinge margin strong, with 3 separate main teeth; ridge; strong, right posterior away from the left one narrow and somewhat furrowed; main teeth; M. meretrix (Linne). Few Shell lateral tooth species, in the Indo-Pacific region. Synonyms Trigona Megerle von Trigonella Conrad, 1837, non either side mantle sinus shallow; margin smooth. Tivela Link, short, on posterior tooth joined with the ligamental Da 1807 1811, non Jurine, 1807; Pachydesma Conrad, 1854. Miihlfeld, Costa, 1778; variable in size, smooth; lunule long; ligament on thick ridges, which are more or less strongly triangular, projecting, wrinkled or beset with tooth-shaped processes; hinge margin on either 1348 main side with 3 A few teeth s. s. Inner margin smooth. Dall, 1891. Inner Section Eutivela (Stearns), more or fairly long, less strong left anterior species, in various seas. Section Tivela — and a mantle sinus in most cases only moderately deep. lateral tooth; T. (T.) mactroides (Born). margin denticulate. T. (B.) perplexa near Brazil. Dosinia Scopoli, 1777 Synonyms Pectunculus Da Costa, 1778; Artemis 1825; Arctoe Risso, (Leach) Basterot, Cerana Gistel, 1848; Shell roundish, (Poli) Oken, 1815; Asa 1826; Exoleta T. Brown, 1827; Amphithaea Leach, 1852. more or less compressed, with concentric sculpture; lunule in most cases small and deepened; ligament in most cases sunken; hinge margin strong, on either side with 3 main teeth, on the a more or furrowed; less left distinct anterior lateral tooth; right left with posterior tooth posterior tooth long, oblique. Several species, in various seas. Subgenus Sinodia Jukes-Browne, 1912. Shell bulging; lunule not depressed; anterior lateral tooth well developed, separated from the main teeth; left median main tooth rounded. D. (S.) Subgenus Dosinia s. s. strong; mantle sinus moderately deep, trigona Reeve. s. s. Lunule distinctly depressed. Section Dosinia Ligamental surface depressed; anterior lateral tooth well developed; median main tooth divided; mantle sinus deep and narrow, ascending. D. (D.) africana Gray. —Section Austrodosinia Dall, 1902. Ligamental left surface indistinctly delimited; anterior lateral tooth strong and rough; median main tooth left strong, undivided; mantle sinus short, not ascending. — (A.) anus Philippi. Section Dosinorbis Dall, 1902 (synonym Phacosoma Jukes-Browne, 1912). Ligamental surface delimited by an D. elevated inner margin and lamellae-shaped ridges; anterior lateral tooth distinct; left median main tooth oblique, undivided; mantle sinus deep {£>.) bilunulata Gray. Section Orbiculus Megerle von and angulate. D. — Muhlfeld, 1811. Ligamental surface not delimited; anterior small; left median main tooth indistinctly divided; ascending, anteriorly rounded. D. (O.) exoleta (Linne). Dall, lateral tooth mantle sinus deep, — Section Dosinidia 1902. Lunule only very slightly depressed; ligamental surface not delimited; tooth small, wart-shaped; left median main and indistinctly divided; mantle sinus deep, angulate, anterior lateral tooth broad ascending. D. (D.) concentrica (Born). — Section Dosinella Dall, 1902. Lunule shallow; ligamental surface indistinctly demarcated; anterior lateral tooth small or reduced; left median main tooth broad and cleft; mantle sinus very deep, ascending, rounded. D. (D.) angulosa (Philippi). 1349 According to Jukes-Browne, Dosinisca Dall, 1902, is based on an abnormal specimen. Iredale has proposed the following "genera" for Australian without diagnoses; Pardosinia, species, Bonartemis, Iredale; 1929, for stabilis Iredale; 1929, for colorata Meridosinia, 1930, for nedigna Iredale; Fallartemis, 1930, for amina Iredale; and Semelartemis, 1930, for aetha Iredale. Cyclina Deshayes, 1849 Synonym Eocyclina 1908. Dall, with more or less distinct growth lines, roundish, bulging, Shell without deepened lunule; ligament strong; hinge margin broad, without lateral tooth; posterior main teeth short and oblique, the right one cleft; mantle sinus deep and ascending. Subgenus Cyclinella Dall, 1902. Shell smaller, weaker and smoother than Cyclina; inner margin smooth; mantle sinus angulate. C. (C.) tenuis near Central America. (Recluz), Subgenus Cyclina small indistinct s. radial s. Shell strong, with rough growth lines and ribs; hinge teeth strong, the left median one sometimes furrowed; inner margin denticulate. C. (C.) sinensis (Gmelin). Few species, near China. Venus Linne, 1758 Synonyms Dosina Gray, 1838; Omphaloclathrum (Klein) Morch, 1853. Shell in most cases strong, roundish or oval, as a rule with distinct concentric, sometimes also radial sculpture; lunule distinct; hinge margin strong, which on is either side with 3 diverging more or main teeth, the left posterior of less joined with the ligamental ridge; anterior lateral tooth in most cases small, wait-shaped, or completely reduced; mantle sinus fairly small; inner margin denticulate. Several species, in various seas. Subgenus Antigona Schumacher, 1817. Shell oval, with radial ribs and strong concentric lamellae; lunule and ligamental surface delimited; directed; main anterior lateral tooth well developed; acutely angled. V. 1930 (persimilis Subgenus distinctly teeth widely diverging, the anteriormost ones anteriorly (A.) lamellaris Iredale), Ventricola is E. mantle sinus small and (Schumacher). Tigammona Iredale, roundish, strongly very similar. Romer, 1857. Shell bulging, with concentric stronger and weaker lamellae, sometimes also with weak radial striae; anterior main teeth only slightly oblique; lateral 350 tooth distinct; mantle sinus small and acutely angled. Chemnitz. Proxichione Iredale, 1929 {materna V. Iredale), (V.) is rugosa scarcely different. Subgenus Dosinula Finlay, concentric lamellae; tooth, which is strong, divided left 1927. Shell oval, with regular sharp valve with long, fairly strong posterior main separated from the ligamental ridge by a deep median and strong, triangular, anterior main pit, with tooth, and with small, wart-shaped lateral tooth; right valve with fairly strong, furrowed posterior, furrowed median, and slender anterior main tooth. V. (D.) zelandica Gray. Subgenus Venus roundish, bulging, V. (V.) s. (synonym Clausina T. Brown, 1827). Shell lamellae and by which the lamellae are tuberculate; anterior tooth very small, wart-shaped, close to the anterior main tooth. irregular radial lateral s. with stronger and weaker concentric ribs, verrucosa Linne (Fig. 836). Fig. 836. Inner and outer side of the right shell valve of Venus verrucosa Linne. Length about 6 cm. Subgenus Periglypta Jukes-Browne, 1914 (synonym Cytherea (Bolten) Roding, 1798, non Fabricius, 1794). Shell strongly bulging, with radial 1351 ribs and concentric lamellae; ligamental surface somewhat asymmetrical; ligament sunken; anterior main anterior lateral tooth tooth; mantle sinus broad and close very small and rounded. to the (P.) puerpera Subgenus Circomphalus Morch, 1853. Shell compressed and flattened, V. Linne. with high, posteriorly canal-shaped elongated, concentric lamellae; hinge margin strongly curved and posteriorly narrowed; anterior lateral tooth very weak; mantle sinus acutely angled. Subgenus Mercenaha Schumacher, Perkins, 1869). Shell oval, bulging, (C.) plicata Gmelin. 1817 (synonym Crassivenus V. with more or less elevated, thin, concentric lamellae; teeth moderately diverging; median main teeth and right posterior one in most cases furrowed; mantle sinus acutely angled. V. (M.) mercenaria Linne. Subgenus Chione Megerle von Muhlfeld, 1811. Shell oval or somewhat triangular, with radial ribs and more or less high concentric lamellae; hinge margin short, with strong main teeth, without tooth; mantle sinus small and angular. Section Chione s. s. lateral Ligamental surface distinctly delimited; concentric lamellae well developed. V. (C.) Linne. Dall, 1902, proposed a section Anomalodiscus for Venus squamosa Linne, which Jukes-Browne did not want to separate cancellata from Chione s. s., although it may be point and the tuberculate radial ribs. distinguished by the sharp posterior — Section Austrovenus Finlay, 1927. Ligamental surface not delimited; concentric lamellae weak. V. (A.) stuchburyi Gray. Section Veremolpa Iredale, 1930. Shell small, without — delimited ligamental surface, with radial ribs and low concentric rings; mantle sinus short and roundish. V. (V.) ethica Iredale. Section Timoclea — T. Brown, 1827 (synonyms Pasiphae Leach, 1852, non Risso, 1826; Leukoma E. Romer, 1857 = Leucoma Stoliczka, 1871, non Stephens, 1829; Murcia E. Romer, 1857, non Koch, 1835). Shell fairly small, oval, without delimited ligamental surface, with radial ribs and sometimes only weak concentric rings; hinge teeth widely diverging; mantle sinus V. (T.) ovata Pennant. blunt or rounded. Subgenus Chioneryx radial ribs and fine Iredale, concentric 1924. Shell small, oval, with narrow lamellae; ligamental surface somewhat deepened; the two anterior main teeth of the right valve anteriorly directed, the median one greatly elongated, the posterior one cleft; on the left the anteriormost one is long, parallel to the margin; the median one thick, cleft, the posteriormost striatissima one weak; mantle sinus angular. V. (C.) Sowerby. Subgenus Clausinella Gray, 1851 (synonym Zucleica Leach, 1852). Shell with concentric sculpture; lunule and ligamental surface distinctly delimited; hinge teeth widely diverging, without lateral tooth; mantle 1352 Shell with regular concentric sinus very small. Section Clausinella s. ridges without elevated lamellae. (C.) fasciata V. s. Da Costa. — Section Lirophora Conrad, 1864 (synonyms Clausina E. Romer, 1857, non T. Brown, 1827; Anaitis Romer, 1857, non Duponchel, 1829). The E. concentric ridges posteriorly form upwardly directed lamellae. Conrad athleta species. Section 1827, non 891 Boie, with narrow, densely placed, rounded Shell 1900). concentric rings; mantle sinus angulate. Tawera Marwick, 1927. Shell with densely placed rings. near (L.) Chamelea Morch, 1853 (synonyms Ortygia T. Brown, 1826; Hermione Leach, 1852, non Blainville, 1828; Parvivenus Sacco, (Powell), V. American f, the living V. paphia Linne, and other mainly New V. {T.) Zealand. (C.) gallina Linne. V. fairly spissa — fine, — Section rounded, more or less Deshayes f, Section Plurigens the living bollonsi 1930. Finlay, Shell with partly somewhat irregular, fairly densely placed concentric rings; ligamental surface fairly narrow and deep; mantle sinus fairly large. (P.) phenax 1925. as (Finaly), near New Zealand. — Section Placamen V. Iredale, Ligamental surface broad, asymmetrical; rings blunt, as broad their intervals; mantle sinus small. (P.) V. placida Philippi, near Tasmania. Subgenus Bassina Jukes-Browne, 1914. Shell with not very densely placed, concentric lamellae; left narrow; lunule narrow. V. median tooth broad, divided; (B.) right teeth pachyphylla Jonas = paucilamellata Dunker. Salacia Jukes-Browne, 1914 (non Lamouroux, 1816, nee Brandt, 1835, nee Boie, 1841, nee Milne-Edwards Iredale, 1917, & Lucas, 1844) = Callanaitis scarcely separable according to Marwick. is Anomalocardia Schumacher, 1817 Synonyms Triquetra (Blainville) Anton, 1839; Cryptogramma Morch, 1853. Shell bulging, anteriorly rounded, posteriorly pointed, mainly with broad, rounded concentric rings; ligamental ridge wrinkled; main teeth strong and widely diverging; mantle sinus very small. Section Anomalocardia flexuosa (Linne). s. s. Few American Inner margin species. — Section denticulate. A. (A.) Cryptonema Jukes- Browne, 1914. Inner margin smooth. A. (C) impressa (Anton), near the Mollucas. Gomphina Morch, 1853 Shell striated; oval or triangular, fairly thick, smooth or concentrically hinge margin broad and short, with 3 main teeth on either side; ligament short; mantle sinus rounded; inner margin smooth. 1353 Few species, in the Pacific Ocean. Gomphinella Marwick, Section 1927. Shell fairly posteriorly shorter than anteriorly; lunule indistinct; right tooth anteriorly curved; Smith, near Dall, 1902). narrow; tooth, main New mantle sinus shallow. Zealand. Section Shell triangular, Gomphina posteriorly s. G. s. small, maorum (G.) oval, median main Edg. (synonym Macridiscus lunule flattened; long and hinge margin on the right with a narrow, furrowed posterior a broadly triangular, tooth; on the left furrowed median one, and a thin anterior with 3 narrow diverging teeth, the median of which is furrowed; mantle sinus moderately deep. (Chemnitz) = veneriformis (Lamarck). G. (G.) donacina Subgenus Psephidia Dall, 1902 (synonym Psephis Carpenter, 1864, non Guenee, 1854). Shell small, smooth, rounded triangular; left posterior tooth free; inner margin very finely denticulate; mantle sinus short and G. (P.) lordi (Baird), near California. triangular. Subgenus Jukesena 1915 (synonym Aeolus Jukes-Browne, Iredale, 1913, non Forster, 1856). Shell small, elongated triangular; hinge on the left with 3, on the margin smooth. G. right with 2 teeth; (J.) mantle line scarcely indented; inner foveolata (Cooper & Preston), near the Falkland Islands. Subgenus Liocyma Dall, 1870. Shell fairly small, triangular oval, concentrically striated; hinge margin on either side with 3 teeth; mantle sinus short; inner margin smooth. G. (L.) fluctuosa (Gould). in Few species, the northern Pacific and Atlantic Oceans. Gemma Shell small, oval Deshayes, 1853 or triangular, smooth or concentrically striated; lunule superficial; hinge margin short, on the right with 3 diverging teeth, the median of which is large and triangular; on the left with 2 or 3 teeth; left anterior dorsal margin and right posterior one with a furrow corresponding to the margin of the other side; ventral margin denticulate. With brood care. Subgenus Gemma s. s. (synonym Tottenia Perkins, 1869). Shell roundish, striated; hinge margin on either side with 3 teeth; marginal furrows distinct; mantle sinus more or less deep. G. (G.) gemma (Totten), near North America. Subgenus Parastarte Conrad, 1862 (synonym Callicistronia Dall, 1883). Shell strong, high triangular, smooth; hinge margin on the right with 3, on the left with 2 teeth; ligament very short; marginal furrows narrow; mantle sinus weak. G. (P.) triquetra (Conrad), near Florida. 1354 Protothaca Dall, 1902 Shell strong, oval, with radial and partly concentric sculpture; lunule distinctly delimited; teeth strong, two median ones and the the right posterior one furrowed; ligament large and strong; mantle sinus acutely inner margin denticulate. angled; Section Protothaca concentric sculpture; s. left Anterior and posterior parts with distinct s. valve somewhat flattened next to the ligament; mantle sinus moderately deep. P. (Lamarck). Marwick, Few thaca (Molina) = dombeyi (P.) species on the west coast of America. 1927. The concentric sculpture flattening beside the (Deshayes), near more is — Section Tuangia extensive, without ligament; mantle sinus short. P. (T.) crassicosta New Zealand. Catelysia E. Romer, 1857 (Katelysia) Shell more or less elongated oval; umbo closer to the anterior end, smooth or concentrically sculptured; lunule somewhat depressed; hinge margin with 3 strong, diverging, often rough teeth, of which the right median and posterior and the left median are furrowed; anterior left and posterior right margin furrowed; mantle sinus rounded; ventral margin smooth. A few species, in the Indo-Pacific region. Subgenus Eumarcia 1857, non Warlow, Iredale, 1833). 1924 (synonym Marcia H. Shell oval, bulging, sculptured; hinge teeth widely diverging, the side furrowed. two & smooth or A. Adams, indistinctly anterior ones of the left C. (£.) fumigata (Sowerby). Subgenus Hemitapes E. Romer, 1864. Shell oval or more or triangular, bulging, sculptured with concentric rings; both anterior teeth simple. less main C. (//.) rimularis (Lamarck). 1857, s. s. (synonyms Metis H. & A. Adams, non 1856; Myrsus H. & A. Adams, 1858; Myrsopsis Sacco, 1900). Shell obliquely oval, more or less bulging, with strong, sometimes somewhat Subgenus Catelysia tuberculate concentric rings; mantle sinus moderately deep. C. (C.) umbo close scalarina (Lamarck). Venerupis Lamarck, 1818 Shell angulate oval, with to the anterior margin; hinge side, more or margin less distinct sculpture; fairly narrow, with 3 teeth on either mantle sinus rounded; ventral margin smooth. 1355 Several species, in various seas. 893 Subgenus Venerupis s. (synonym Pulldstra Sowerby, s. Surface with fine sculpture, which (V.) V. perforans (Montagu) = pullastra (Montagu). Subgenus Amygdala E. Romer, 1 857 (synonym Ruditapes Chiamenti, with fine radial ribs and more or less distinct concentric Shell 1900). margin narrow; posterior teeth very rings; hinge V. 1826). stronger in the posterior part. is short; mantle sinus deep. decussata (Linne). (A.) Subgenus Polititapes Chiamenti, 1900. Shell longish, posteriorly not with angulate, concentric fine rings narrow and long; mantle sinus and fairly indistinct short, radial rounded. V. ribs; lunule (P.) aurea (Gmelin). Callithaca Dall, 1902 Shell oval, times with most cases with narrow concentric lamellae, some- in radial fine ligament large; striae; posterior hinge teeth depressed; short; lunule more or less mantle sinus angular; ventral margin smooth. Subgenus Rhomalea Jukes-Browne, 1914. Shell roundish, with weak radial striae and in the ventral part with stronger concentric rings; mantle sinus acutely angled. C. (R.) rufa (Lamarck), near Peru. Subgenus Humilaria Grant longish oval; umbo & Gale, 1931. Shell medium-sized, close to the anterior end; surface with concentric lamellae, without radial sculpture; mantle sinus moderately deep. C. (//.) kennerleyi (Reeve), on the American west coast. Subgenus Callithaca anterior end; placed radial surface striae; s. s. Shell large, longish oval; umbo close to with narrow concentric rings and fine, densely- mantle sinus very deep and acutely angled. C. (C.) tenerrima (Carpenter), near California. Paphia (Bolten) Roding, 1798 Shell more or lunule distinct; less elongated, smooth or concentrically sculptured; hinge margin narrow, with short, fairly closely placed and moderately diverging teeth; mantle sinus moderately deep, rounded; inner margin smooth. A few species, in the Section Protapes Dall, tric one Indian Ocean. 1902. Shell triangular, with narrow concen- rings; lunule large, long; cleft. Paphia s. P. s. (P.) median hinge teeth and the right posterior = malabarica (Dillwyn). Section gallus (Gmelin) — (synonyms Eutapes Chiamenti, 1900; Callistotapes Sacco, 1356 1900). Shell long, compressed, with flat concentric rings; lunule long and narrow; mantle sinus obliquely ascending. P. (P.) alapapilionis Roding — 837). Section Paratapes Stoliczka, 1871 (synonym Textrix E. Romer, 1857, non Sundeval, 1833). Shell long, smooth or with weak (Fig. concentric sculpture; lunule narrow; mantle sinus fairly short. P. textile (Gmelin) = Fig. textrix (P.) (Chemnitz). 837. Shell of Paphia alapapilionis Roding. Length 8.5 cm. 894 Tapes Megerle von Muhlfeld, 1811 Synonym Parembola anteriorly E. Romer, 1870. elongated oval, with umbones close to the anterior end, Shell somewhat pointed, posteriorly broadly flattened, with densely placed concentric rings; lunule long and narrow; and deeply cleft, left median tooth broad the remaining teeth simple; mantle sinus moderately deep, rounded, not ascending; margin smooth. T. litterata (Linne). Few species, in the Indo-Pacific region. dementia Gray, 1842 Synonym Blainvillia Hupe, 1854, non Desvoidy, 1830. Shell oval, bulging, thin; umbo more or less close to anterior end, projecting; lunule indistinct; ligament short; hinge margin weak, anterior to the teeth deepened pit-like, posterior of which on either side with 3 teeth, the right most cases cleft; mantle sinus variable. Animal with long siphons, which are completely fused; mantle margin smooth; foot is in compressed. Few species, in various seas. Subgenus Compsomyax Stewart, 1930. Shell very thin; umbo moderately parts diverging. C. (C.) America. fairly elongated oval, not elevated; right posterior tooth deeply cleft, its subdiaphana Carpenter, on the west coast of North 1357 Subgenus dementia umbo folds; s. Shell very thin, with irregular concentric s. high, close to the anterior end; right posterior tooth long, narrowly forked. C. (C.) papyracea (Gray), straight, in the Indo-Pacific region. Subgenus Terentia Jukes-Browne, 1914. Shell longish, with hinge teeth short, obliquely crossed striae; lar, all irregu- undivided, right posterior one thin; mantle sinus very large and deep. C. (T.) granulifera Sowerby. Notopaphia Oliver, 1923 Shell long and low; and concentric ribs umbo blunt, closer to the anterior end; lunule ligamental surface narrow; surface with fine radial distinctly delimited; which rings, in the posterior part expand into lamellae; teeth short, on the right the 2 posterior ones cleft; on the left the median is distinct, the anterior one indistinctly furrowed, the poste- one joined with the ligamental ridge; mantle sinus acutely angled; rior margin denticulate. elegans (Deshayes), near N. lrus Shell in most cases variously sculptured; New Zealand. Oken, 1815 more or fairly small, longish, often umbo less irregular, closer to the anterior end; lunule not delimited; hinge margin narrow and very short; teeth often irregular, in most cases 2 on either side are furrowed; lower margin smooth. A few species, in various seas, in Subgenus Paphirus with Finlay, concentric threads furrowed, as well rounded. right Subgenus Notirus Finlay, 1865). Shell fairly striae; posterior one; (P.) largillierti (Philippi), near /. Ironus Bastian, teeth most cases living Shell and weak radial the as 1927. New large, in holes. longish oval, median hinge teeth mantle sinus broadly Zealand. 1928 (synonyms Irona Finlay, 1927, non longish, somewhat downwardly prolonged. with concentric lamellae; /. hinge (N.) reflexus (Gray), near New Zealand. 895 Subgenus lrus s. s. Shell with narrow radial ribs and more or less somewhat elevated concentric lamellae; mantle sinus in most cases short, angular. /. (/.) irus (Linne). 2. Shell in most cases Family PETRICOLIDAE fairly small and colorless, roundish or elongated; ligament external, fairly short; hinge margin on the right with 2, on the 1358 left with sinus 3, sometimes irregular main more or less deep. without teeth, Siphons long; lateral teeth; mantle laminae folded; foot with or gill without byssal furrow. Mysia (Leach) Lamarck, 1818 & Synonym Lucinopsis Forbes Hanley, 1848. roundish, colorless, concentrically striated; Shell thin, umbo fairly pointed, anteriorly inclined; hinge margin on the right with 2 thin teeth, on the left mantle with 3 teeth, the median of which is fairly broad and forked; rounded. Siphons long and separate. line large, M. undata (Pennant), near Europe. Lajonkairea Deshayes, 1854 Shell short, somewhat quadrangular, anteriorly shortly rounded, posteriorly high; surface with fine, rough radial ribs; ligament sunken; hinge teeth similar to those in Mysia; mantle sinus very broad. Siphons fused. L. in the lajonkairei (Payraudeau). Red A couple of European species and one Sea. Cooperella Carpenter, 1864 Synonyms Oedalia Carpenter, 1864, non Meigen, 1820; Oedalina Carpenter, 1865. Shell small and very thin, roundish, inflated, nearly smooth; hinge margin on the C. left with 3, on the right with 2 teeth; mantle sinus deep. subdiaphana Carpenter, near California. Petricola Lamarck, Shell more or less 1801 elongated, often irregular, anteriorly short and rounded, posteriorly narrowed, with variably strong, sometimes oblique radial ribs; variable. anterior hinge teeth are sometimes reduced; mantle sinus Mantle with a small opening for the foot and 2 long, largely separate siphons; foot small, with byssal groove. Few species, in various seas. The animals bore into Subgenus Velargilla brown mud, soft limestone, or corals. Iredale, 1931. Shell moderately long, reddish with rays, thin, with dense, oblique, irregular small ribs; to the anterior end. P. (V.) rubiginosa (Adams umbo not close & Angas), near Port Jackson. 1359 Subgenus Naranio Gray, 1853. Shell with oblique fairly short oval, mantle sinus very broad. P. (N.) lapicida or zig-zag-shaped threads; (Chemnitz). Subgenus Petricola 1802; s. (synonyms Rupellaria Fleuriau de Bellevue, s. Choristodon Jonas, 1844). anteriorly short Shell and inflated, posteriorly thinned and elongated; sculpture radial; mantle sinus broad, rounded. P. (P.) lithophaga Retzius. Subgenus Claudiconcha 896 inequivalve, P. Fischer, 1887. Shell irregularly roundish, with radial ribs and in part broadened concentric rings; posterior margin of the right shell widened and enclosing that of the left shell; mantle sinus fairly short and angular. P. (C.) monstrosa (Chemnitz). Subgenus Petricolaria Stoliczka, 1871 (synonym Gastranella Verrill, 1872). Shell in most cases greatly elongated, similar to that in Pholas with radial ribs, in the anterior part, with stronger, rough radial ribs; mantle sinus very deep. P. (P.) pholadiformis Lamarck (Fig. 838). Fig. 838. Petricola (Petricolaria) pholadiformis Lamarck. Length 5.5 cm. XIV. STIRPS Shell equivalve, MACTRACEA triangular or oval more elongated, closed or or gaping; ligament with large internal cartilage posterior to the main teeth; hinge margin on the on the left with an often cleft or angle-shaped main tooth, right with 2 teeth clasping it, on the left a posterior lateral tooth, and corresponding to also with an anterior them on the right and having furrows with elevated margins; mantle sinus variable. Siphons partly or completely fused, in most cases with a cuticula and with tentacles end ; mantle more or less widely open; gill at the laminae smooth; oral lobes long and narrow; foot large, without byssus. 1. Family Shell equivalve, in MESODESMATIDAE most cases longish triangular; posteriorly shorter than anteriorly, seldom transversely oval, strong, smooth or concentrically striated, with distinct periostracum; external ligament small, 1360 one internal in a more or less has an anterior and posterior inwardly projecting lateral tooth in the left ing pits in the right valve and mainly below left pit; the hinge margin valve and correspond- them with teeth, on the with one main tooth anterior to the ligamental cartilage and sometimes posterior to it with a smaller or larger lamella, on the right with 2 main teeth, the anterior of which lower anterior lateral tooth; muscle scars most cases joined with the in is fairly large; mantle line in most cases with a small angular or roundish indentation. Siphons completely on the ends with separate, margin smooth; foot papillae; mantle large, triangular, without byssus; gill laminae folded, unequally broad; labial palps triangular. ? Shell Nesis Monterosato, 1875 smooth and shiny, transversely small, colorless, oval; umbo close to the posterior end; ligamental cartilage weak, posterior to it a short, angularly projecting ridge; hinge margin on the with a simple, on the right left with with a forked main tooth, without lateral teeth; adductor muscle scars large, oval; mantle line close to the margin, unindented. N. prima Monterosato, in the Mediterranean Sea. Davila Gray, 1853 Shell fairly small, rounded triangular, compressed; ligamental carti- lage moderately large, in the 897 left valve its anterior and posterior margins are elevated tooth-shaped and the lateral teeth are short center; in the right valve the lateral tooth is is and close to the very weak, the posterior strong, furrowed; mantle line unindented. D. plana (Hanley). Islands, main tooth A couple of species, near the Philippines, Sunda and eastern Australia. Anapella Dall, 1895 Synonym Anapa Gray, 1853, non 1847. Shell triangular oval, inflated, concentrically sculptured, posteriorly longer than anteriorly and somewhat pointed; ligamental cartilage strong; left valve with a strong, furrowed main tooth, and with long lateral teeth; right valve with a forked main tooth and distinct lower lateral teeth; mantle line unindented, posteriorly straight. A, triquetra (Hanley) (Fig. 839). and Tasmania. Few species, near South Australia 1361 Fig. 839. Hinge margins of Anapella thquetra (Hanley), enlarged. Ervilia Turton, 1822 Shell small, compressed, elongate oval, posteriorly longer than anteriorly, moderately thick, smooth or concentrically sculptured; what projecting; external ligament more or less umbo some- rudimentary; cartilage triangular, scarcely projecting interiorly; left valve with a weak main and a similar adjacent anterior lateral tooth, as well as a short posterior lateral valve with tooth; right tooth and strong one main tooth and a short posterior lateral tooth; mantle sinus fairly deep, oval. A nitens (Laskey). E. Iredale, few species, in and posteriorly radially striated ? Shell fairly large and concentrically striated; E. for the anteriorly australis Angas. Caecella Gray, 1853 thin, umbo somewhat inflated, elongated oval, finely more or downwardly close to the center, ligament rudimentary; cartilage external various seas. 1930, proposed a "genus" Spondervilia pit less projecting; projecting; left valve with one main tooth and short lateral teeth; right valve with a divided main tooth, the anterior cusp of which tooth, and a somewhat longer posterior is fused with the lateral lateral tooth; mantle sinus fairly small. C. horsfieldi Gray. Few species, in the Pacific Ocean. Argyrodonax Dal I, 1911 Shell small, somewhat triangular, posteriorly pointed, shorter than anteriorly, exteriorly concentrically sculptured; ligamental cartilage narrow, but strong; main teeth weak; lateral teeth on the right fitting below the margin of the left shell, the anterior one short and strong, the posterior one elongated, high and thin; mantle sinus deep, fused with the mantle line. A. haycocki Dall, near the Bermudas. 1362 Mesodesma Deshayes, 1830 Shell more or most cases compressed, in triangular, anteriorly longer than hinge margin strong, with variably long posteriorly; less strong main teeth; lateral teeth' and mantle sinus small. Several species, in various seas. Section Atactodea Dall, 1895 (synonym Paphia Lamarck, 1801, non 898 Roding, 1798). Shell fairly than posteriorly, bulging; slightly projecting short triangular, anteriorly scarcely longer hinge strong, although ligamental downward, on the left its pit only two margins, especially the anterior one, are distinctly elevated; the anterior lateral tooth longer than main tooth is scarcely M. (A.) glabratum (Gmelin). Section Paphies Lesson, 1830 (synonym Machaena (Leach) Gray, 1843). Shell elongated oval, anteriorly somewhat longer than posteriorly, the posterior; on the right the posterior part of the developed; the inner lateral compressed; cartilage pit interiorly distinctly projecting; — teeth strong. left valve with a simple main tooth and fairly short lateral teeth; right valve with strong inner lateral teeth; posterior part of the main tooth rudimentary; mantle sinus M. angular. small, —Section (P.) novaezelandiae Donacilla (Lamarck) Philippi, 1836. Shell (Chemnitz). compressed, anteriorly distinctly elongated; ligamental pit scarcely projecting below, anterior to it on the a left weak main tooth, posterior to it a strong lamella and a very short posterior lateral tooth, whereas the anterior one is elongated; right valve with a forked main tooth, with double anterior lateral to and a short thick posterior teeth roundish. M. (£>.) triangular, corneum anteriorly strong; left valve with the teeth; right (Poli). — lateral tooth; mantle sinus Section Taria Gray, 1853. Shell oval more or less elongated; ligamental cartilage one main tooth and fairly short, smooth lateral main tooth merging into the anterior lateral tooth; mantle M. (T.) quoyi Deshayes. Iredale, 1930, proposed the "genus" Amesodesma for the eastern Australian species perfuga. Section Mesodesma s. s. (synonym Ceronia Gray, 1853). Differing from Taria "mainly by the transverse grooves on the lateral teeth; main teeth fairly weak; mantle sinus roundish. M. (M.) donacium (Lamarck) sinus sometimes deep. (Fig. 840). 2. Family MACTR1DAE Lateral teeth present as a rule and mantle sinus of variable size. 1363 Fig. 840. Internal side of the right shell valve of Mesodesma donacium (Lamarck). Length about 8 cm. Rangianella Conrad, 1868 umbo Shell fairly small and strong, triangular, posteriorly angular; projecting, close to the center; cartilage not separated from the external ligament, fairly small, not projecting inwardly; main teeth weak. Lateral teeth moderately long; mantle sinus small. Subgenus Rangianella s. In the right valve the taller anterior s. tooth and a small angle arch over the on the cartilage; left main tooth anterior to the with a cleft main tooth and an angle anterior to the upper part of the cartilage; 899 weak main sinus scarcely deepened. R. lateral (/?.) teeth not distinctly grooved; mantle mendica (Gould). On the coasts of North and Central Amercia. Subgenus Notospisula the posterior one short; left Iredale, 1930. Main teeth of right valve weak, valve with a distinctly forked main tooth and with a short tooth at the corner anterior to the cartilage; lateral teeth distinctly grooved; mantle sinus fairly shallow. R. (N.) parva (Petit). A couple of Australian species. Rangia Des Moulins, 1832 Synonyms ? (Gray) Sowerby, Shell Clathrodon (nom. nud.) Conrad, 1831, non Oken, Gnathodon very thick, with high umbones close to the anterior end; cartilage strong, not separated tooth of 1830; 1816. left from the ligament; the hook-shaped main valve clasps the posterior main tooth of right valve and embraced anteriorly by the other tooth; lateral is teeth distinctly grooved, the posterior one very long, parallel to the margin, the anterior one less 1364 on the long, enclosing hook-shaped the initially high lateral tooth of left the right valve; mantle sinus small, but distinct. Siphons short, fused at base. Gulf of Mexico. R. cuneata (Gray), in the Mulinia Gray, 1837 umbones Shell strong, greatly bulging, oval with high to the middle, with strong periostracum; ligament in a common and not exteriorly pit situated close and cartilage enclosed visible; left valve with a forked main tooth and a small posterior lamella; right valve with 2 thin main forming a right angle and a small denticle above the cartilage pit; sinus teeth mantle deepened, tongue-shaped. distinctly M. edulis (King). A few American species and one from East Africa. Spisula Gray, 1837 medium Shell of to considerable size, more or less bulging, rounded most cases closed; umbo somewhat elevated and close to concentrically striated; external ligament not separated from triangular, in the center, by a calcareous lamella; lateral teeth often grooved; mantle more or less large. Subgenus Spisula s. s. (synonym Spisulina P. Fischer, 1887). Shell the cartilage sinus bulging, fairly small, umbo close to the center; which is triangular, left closed; upper part distinctly covered above by the main teeth of the right valve; grooved; mantle sinus fairly small, tongue-shaped. A few mainly European anterior Hemimactra s. s. lateral lateral teeth S. (S.) solida (Linne). species. Subgenus Hemimactra Swainson, 1840. Shell closed; striated; valve with an angle-shaped main tooth, teeth large, oval triangular, very close to the main teeth. Section Right anterior main tooth joined with the lower lateral tooth; lateral teeth grooved; mantle sinus short, rounded. S. (//.) solidissima (Chemnitz). Few species, near North America. — Section Mactromeris Conrad, 1868. Lateral teeth smooth, the lower ones of the right valve weak, without junction with the main tooth; mantle sinus polynyma (Stimpson) (Fig. 841), near North proposed the section Symmorphomactra for America. large. S. (M.) — 1894, Dall, Gould from the S. falcata North American west coast; according to Finlay, 1928, belonging here 900 are his "genera" Scalpomactra (scalpellum Deshayes) (elongata Quoy & Gaimard) from New Hemimactra versicolor Tate from South Zealand. Australia, and Longimactra The for relationship which 1930, proposed the genus Diaphoromactra, seems doubtful. Austromactra Iredale, 1930. Shell triangular, of — Iredale, Section with distinct concentric 1365 lateral rings; main teeth; Australia. — teeth smooth, moderately long, without connection to the mantle sinus short, roundish. Section with concentric rings; in the tooth lateral S. main tooth; Few and forms a lamella just species, in the Pacific Ocean. 841. Shell margins of Spisula (Mactromeris) polynyma (Stimpson) (after Subgenus Leptospisula umbo triangular, grooved; mantle sinus deep. teeth lateral (O.) triangularis (Lamarck). Fig. caloundra Iredale, near valve the posterior end of the anterior left separated by a depression is the anterior to S. (A.) Oxyperas Morch, 1853. Shell elongated Lamy). 1895. Dall, Shell bulging, large, gaping; closer to the anterior end; lateral teeth short, smooth; mantle sinus deep, tongue-shaped. S. (L.) striatella (Lamarck), near West Africa and on the east coast of South America. Subgenus Schizodesma (Gray, 1837) Swainson, 1840 (Scissodesma). Shell triangular, another, between cleft, below the cleft shaped is left lies the external this the cartilage in thickened and projects main tooth high; tongue-shaped. S. umbones posteriorly angulate; them (S.) very deep at the far away from one ligament in a half-moon-shaped pits; the posterior margin of end as roundish tooth; the angle- lateral teeth short, granulose; mantle sinus spengleri (Linne), near South Africa. Mactra Linne, 1767 Shell triangular or oval, often somewhat gaping; from the ligament by a calcareous lamella; mantle sinus variable in size, lateral cartilage separated teeth not grooved; rounded. Siphons completely fused, partly enveloped by a cuticula. Numerous species, in various seas. Subgenus Mactra s. s. (synonym Trigonella Da Costa, 1778, non Walch, 1762, nee Schroter, 1776). Shell bulging, triangular, posteriorly scarcely gaping; umbo close to the center, more or less high; mantle Nannomactra Iredale, 1930. Shell small and thin, dorsally not more strongly sculptured; hinge margin weak; sinus short. Section fairly long, cartilage pit small; thin. M. main teeth diverging at a right angle; lateral (N.) jacksonensis Edg. Smith, near eastern Australia. — teeth Section 1366 Mactra s. s. Shell larger and stronger; umbo elevated, dorsal parts not grooved; main teeth of the right valve not connected; large. M. (M.) stultorum Linne (Fig. 842). — lateral teeth fairly Section Maorimactra Finlay, 1928. Shell small and thin, anteriorly shorter, dorsally sharply ribbed; cartilage small; lateral Iredale, 901 mantle sinus broad and shallow. M. teeth long; (M.) ordinaria Edg. Smith, from New Zealand. — Section Calorimactra 1929. Shell fairly short, anteriorly rounded, posteriorly angulate, thin; umbo high, with stronger striae; main teeth; mantle sinus short. M. (C.) queenslandica Edg. Smith, near — Deshayes. — Queensland. Section Telemactra Iredale, inflated, with dorsal folded striae; teeth lateral 1929. short, Shell close to the triangular, mantle sinus very short. M. (T.) thin, obesa Section Coelomactra Dall, 1894. Shell fairly large and thin, longish triangular, bulging; hinge margin fairly broad, the anteriormost main teeth of both valves situated on a lamella, which covers the posterior, strongly depressed part with the thin anterior lateral teeth. (C.) M. violacea Chemnitz. Fig. 842. Shell of Mactra stultorum (Linne). Subgenus Mactroderma Dall, 1894. Umbo close to the anterior end; hinge margin broad with large, triangular cartilage; mantle sinus large. Section Cyclomactra Dall, 1894. Shell main teeth M. (C.) tristis Section Mactroderma anterior right main tooth roundish; anterior situated in the prolongation of the anterior lateral teeth. New Deshayes, near s. s. Zealand and Australia. Shell large and strong, longish triangular; extending to the short anterior — lateral tooth; posterior lateral teeth short and strong; mantle sinus broadly rounded. M. (M.) velata American west Philippi, on the coast. Subgenus Mactrotoma Dall, 1894. Shell compressed, longish, posteriorly often distinctly gaping; cartilage teeth very short, continuing posteriorly pit large; anterior lateral and dorsally by a lamella. Section 1367 Micromactra and strong; umbo furrowed. M. Dall, 1894. Shell small califomica Conrad. — (A/.) Section Simomactra Dall, 1894. Shell only slightly gaping; accessory lamellae separated from the lateral teeth, mantle sinus M. fairly small. Shell distinctly dolabriformis Conrad. (S.) — Section Mactrotoma s. mantle sinus large and anterior lateral teeth joined with the lamellae; M. (M.) broad. s. gaping, posterior part delimited by a depressed band; Chemnitz. Pseudoxyperas Sacco, fragilis proposed for the Tertiary species still living 1900, on the West African was coast, M. proaspera Sacco, which is considered by Lamy as M. (Mactrotoma) aspera Sowerby forma egena Deshayes. Subgenus Mactrella Gray, 1853 (synonym Papyrina Morch, 1853). Shell triangular, posteriorly with a more or longish, less high lamella; surface with mantle sinus lines or strong folds; Shell indented anterior to the umbones, colorless, thin, fairly large. weak concentric Section Mactrella s. s. with fine concentric threads, without delimited lunule, posteriorly gaping; left valve with a pit above the anterior cusp of the main tooth and below its anterior end with a pointed lamella, which is separated from the anterior lateral tooth by an indentation; pits are also present above and anterior to the anterior main tooth of the right valve. M. Spengler. alata (A/.) Iredale, main anterior to the M. tooth. lateral In tropical America. — Section Electromactra 1930. Shell smooth and shiny; lunule not distinctly delimited; — teeth (E.) on either side, a depression divided by the parkesiana Hedley, near eastern Australia. Section Harvella Gray, 1853. Shell roundish, strongly bulging, with strong concentric folds; lunule distinctly deepened; hinge margin similar to that in Mactrella; lateral teeth short; elegans Sowerby, near Panama. — mantle sinus M. large. Section Mactrinula Gray, (//.) 1853. Shell compressed, longish, with strong concentric folds and distinct lunule; hinge margin broad, below the anterior main tooth on either side with a short accessory lamella, which tooth; posterior lateral tooth high. not continuous is M. (A/.) plicataria with the lateral Linne. Near southern Asia. Labiosa (Schmidt) Moller, 1 832 Synonyms Anatina Schumacher, 1817, non Lamarck, 1816; Cypricia Gray, 1847; Leucoparia C. Mayer, Shell thin, compressed; 1867. posteriorly gaping, umbo projecting, anteriorly bulging, situated posteriorly behind the center; cartilage separated from the ligament by a calcareous lamella; hinge margin broad and short; main teeth similar to those in Mactra; lateral teeth more or 1368 Siphons naked, completely rudimentary. less retractile; mantle partly closed below. A few species, s. s. seas. Shell longish oval, fairly large, concentrically with a posterior radial ridge, broadly gaping; lunule delimited striated, by a warm in Subgenus Labiosa flat furrow; lateral teeth very short and close to the main teeth, on either side with an anterior anteriorly rounded. L. (L.) one and a posterior one; mantle sinus broad, anatina (Spengler). A couple of American species. Subgenus Raeta Gray, 1853 (synonym Lovellia C. Mayer, 1867). somewhat gaping, with concentric the margin extending posteriorly from the Shell inflated, posteriorly angulate and folds; a ridge parallel ligamental s. pit; to mantle sinus deep, anteriorly angulate. Section Raeta Shell variable in size; small posterior lateral teeth present. L. {R.) s. canaliculata (Say). — Section Raetina Dall, 1894. Shell small, without posterior lateral teeth. L. (R.) indica (Dall). Subgenus Raetella Dall, 1894. Shell very small and thin, shiny, roundish, with short beak, without lateral teeth. L. (R.) tenuis (Dall), from China. Standella Gray, 1853 Shell oval, anteriorly and posteriorly gaping, often with radial sculpture; umbo situated anterior to the center; cartilage the main by ligament not separated from the a calcareous lamella; anterior lateral teeth short and close to tooth; lateral teeth smooth, double in the right valve; mantle sinus deep and anteriorly rounded. Subgenus Standella Shell fairly thin, s. s. (synonym Merope H. posteriorly elongated; left & A. Adams, 1856). main tooth angle-shaped; anterior lower lateral tooth of the right valve joined with the anterior main Shell — S. tooth. Few species, in the Indo-Pacific area. Section Standella without distinct radial sculpture. S. (S.) s. s. pellucida (Chemnitz). Section Meropesta Iredale, 1929. Shell with numerous radial threads. (A/.) meridiana Iredale. Subgenus Eastonia Gray, 1853. Shell strong, bulging, roundish oval, main tooth scarcely diverging; right with distinct radial sculpture; anterior anterior left main tooth very short; the lower lateral tooth high, adjoining the main tooth. S. (E.) rugosa (Helbling),in the Mediterranean Sea and the neighboring Atlantic Ocean. 1369 Heterocardia Deshayes, 1854 Shell triangular oval; striated; cartilage lamella; left umbo close to the center; surface concentrically separated large, from the ligament by a calcareous valve with a high angle-shaped main tooth the short high right anterior main tooth joined with the lower or upper lateral teeth; lateral tooth; mantle sinus large. H. gibbosula Deshayes. A couple of species near the Philippines. Schizothaerus Conrad, 1853 Synonyms Cryptodon Conrad, 1837, non Turton, 1822, nee Tresus Gray, 1833; 1853, non Walkenaer, very large and strong, oval, bulging, concentrically striated, Shell posteriorly widely gaping; strong, separated weak; Latreille, 1833. left umbo situated anterior to the center; cartilage from the ligament by a calcareous lamella; hinge teeth main tooth angle-shaped; right anterior main tooth joined with the short lower lateral tooth; mantle sinus very large. nuttalli (Conrad), 5. in the northern Pacific Ocean. Lutraria Lamarck, 1799 Synonyms Cacophonia + Eustylon Gistel, 1848. Shell elongated, more or less compressed, broadly gaping ends, concentrically striated, slightly elevated, with distinct periostracum; the at umbo only situated anterior to the center; cartilage pit obliquely posteriorly directed; left main tooth high; with the short anterior lateral tooth; right anterior main tooth joined posterior lateral weak or teeth absent; mantle sinus very deep, anteriorly rounded. A few species, in various seas. Subgenus Lutraria s. s. Shell elongated oval; ligament separated from the cartilage by a calcareous lamella; right anterior lateral tooth situated in the process of the main tooth. Section Lutraria posteriorly moderately elongated; right posterior posterior lateral teeth Lutromactra Iredale, smaller, but C. Mayer, parallel is 1867, dorsal very weak. L. (I.) lutraria s. s. Shell fairly high; (Linne) (Fig. 843). 1929 [impedita Iredale = elongata (Gray)] otherwise scarcely different. is main tooth different — Section by the greatly elongated and ventral margins. L. (G.) is Goniomactra shell with nearly impar Deshayes. — Section Lutrophora Dall, 1894. Shell greatly compressed, elongated oval, with strong concentric sculpture; right posterior main tooth posteriorly appressed; posterior lateral teeth distinctly developed, but without the upper ones of the right side. L. (L.) planata (Chemnitz). 1370 843. Inner side of the Fig. left shell valve of Lutraria lutraria (Linne). Length about 12.5 cm. Subgenus Psammophila (Leach) T. Brown, 1827. Shell elongated, dorsally 904 somewhat concave; umbo close to the anterior end; ligament not separated from the cartilage by a lamella; left main tooth compressed; main tooth high, the anterior one situated close beside the lateral tooth, separated by a cleft. L. (P.) oblonga (Chemnitz). right posterior anterior Darina Gray, 1853 at Shell fairly small, thin, elongated oval, compressed, somewhat gaping umbo scarcely elevated, both ends, smooth, with distinct periostracum; situated posterior to the center; cartilage only slightly oblique, not separated from the ligament by a calcareous lamella; left main tooth with anterior limb and small posterior limb; right anterior larger main tooth joined with the small lateral tooth; posterior lateral teeth short; mantle sinus moderately deep, anteriorly rounded, joined with the mantle line. D. solenoides (King), near Tierra del Fuego. Vanganella Gray, 1851 Synonyms Resania Gray, 1853; Myomactra + Laminaria C. Mayer, 1867. Shell fairly large, thin, compressed, elongated oval, anteriorly somewhat pointed, concentrically striated, with yellowish periostracum; umbo not projecting, situated somewhat posterior to the center; cartilage large, obliquely posteriorly directed, not separated from the ligament by a calcareous lamella; the cartilage bearer is which descends from the ligament anterior muscle fused with a strong ridge, to the posterior adductor scar; a flatter ridge lies posterior to the anterior scar; left main tooth strong, with equal limbs; lateral teeth teeth fairly thin, diverging at a right angle, the anterior adductor muscle weak; right main one fused with the 1371 small lateral tooth; mantle sinus broad, extending to the posterior ridge, joined with the mantle V. line. New taylori Gray, near Zealand. Zenatia Gray, 1853 Synonym Metabola Shell periostracum; the C. Mayer, compressed, umbo bearer at more or not projecting, triangular cartilage 1867. gaping thin, is the ends, with brownish less close to the anterior end; posteriorly attached the to shell; ligament not separated from the cartilage by a calcareous lamella; main tooth with equal limbs, its anterior lateral tooth, the posterior one very weak; right strong; mantle Z. lateral teeth left anterior limb is parallel to the short main teeth fairly rudimentary; mantle sinus deep, joined with the line. & acinaces (Quoy (victoriae Pritchard New Gaymard) near & Gatliff) near 3. Family Zealand, and one species South Australia. ANATINELLIDAE Shell roundish oval, bulging, fairly thin, colorless, anteriorly rounded, posteriorly angulate striated and only and with very slightly radial fine center; ligament small, not separated the cartilage bearer projects far fairly strong left main tooth is gaping; lines; umbo surface concentrically elevated, close to from the large club-shaped downward and somewhat backward; weakly the cartilage; cleft, parallel to its anterior the margin runs a rudimentary anterior lateral tooth; the two right main teeth form an acute angle; probably a small lateral tooth is completely fused with the anterior tooth; posterior lateral teeth absent; the anterior margin of the posterior adductor muscle scar is thickened; the two scars and the mantle line situated very close to the margin, parallel to the this line posteriorly runs margin without indentation. Animal unknown. Anatinella Sowerby, 1834 Characters of the family. A. Candida (Chemnitz), ? 4. in the Indo-Pacific region. Family CARDILIIDAE Shell greatly bulging, higher than long, with very strong, anteriorly spirally inrolled umbones, colorless; external ligament short; cartilage on 1372 a short and broad, anteriorly deepened plate, which below the cartilage bears high and narrow teeth, and on the right with a triangular main tooth and between fits it and the cartilage a half-moon-shaped tooth; between them the channel-shaped of the right valve adductor muscle scar tooth; a left weak ridge on the anterior margin perhaps a rudimentary is lateral tooth; the anterior long and narrow, close to the anterior margin; is the posterior adductor muscle is attached to an erect lamella; a mantle sinus absent. Cardilia Deshayes, 1835 Synonyms Hemicyclonosta ? Hemicyclostera Bronn, (Bonelli) Pictet, (Deshayes) Michelin, 1838; Hemicyclodonta Deshayes, 1828; 1850; Leptina 1855. Characters of the family. Fig. 844. Hinge margins of Cardilia semisulcata (Lamarck) (after C. semisulcata (Lamarck) Lamy). (Fig. 844). Few species in the Pacific Ocean (Japan to Australia). XV. STIRPS TELLINACEA Shell in most cases somewhat asymmetrical, compressed, oval or on either side with 2 main teeth and often also with triangular, as a rule lateral teeth; mantle sinus deep, not seldom completely or largely continuous with the mantle more or less open; smooth or folded, foot line. in Siphons long, separate; mantle ventrally most cases without byssus; in the posterior part cross-shaped muscle. gill laminae of the mantle as a rule with a 1373 1. Family equivalve, triangular or elongated, Shell smooth or sculptured; ligament short, more or bulging, compressed, less attached in furrow; a on short ridges; hinge margin as a rule with 2 main teeth on cartilage either side; lateral teeth is DONACIDAE may be reduced; the right anterior dorsal margin often distinctly furrowed; mantle line in most cases strongly indented: Mantle completely open below. inner margin often denticulate. Hemidonax Morch, 1870 Synonym Donacicardium strong, Shell Vest, 1875. anteriorly triangular, somewhat longer and rounded, by an edge; surface radially ribbed; umbo strong; hinge margin on the left with 2 main teeth and an anterior and a posterior lateral tooth, on the right with 2 diverging main teeth and posteriorly flattened and delimited 2 anterior and 2 posterior lateral teeth; mantle line not indented; inner margin strongly denticulate. Animal unknown. donaciformis (Spengler), near Australia and the Philippines. H. Because of the unindented mantle line, this species was earlier included with the cardiids, but recently with the donacids; Fischer has placed it which is with the fossil genus Tancredia Lycett Donax Synonyms Cuneus Da Shell triangular or umbo fairly lateral teeth side; small; family Tancrediidae, less 1758 1778; Capisteria Meuschen, Costa, elongated, ligamental more or Linne, posteriorly shorter than cartilage fairly long, separate, 1787. anteriorly; sometimes somewhat sunken; distinctly developed, mantle sinus deep and rounded; margin Siphons in a similar to the donacids. in 2 main teeth on either most cases denticulate. unequal; mantle margin beset with papillae; laminae variable, sometimes smooth and with identical filaments, sometimes folded with large inner border filaments; outermost lamella gill broadened; foot without byssus. Fig. 845. Inner side of the left shell valve of Dona.x rugosus Linne. 1374 warm Several species in temperate and seas, living in sand close to the shore. Section Chion Scopoli, 1777. Shell fairly strong, triangular, posteriorly sharply truncated; denticulatus Linne. different surface with punctate radial developed; distinctly — ventral Section Deltachion from Chion. D. (D.) furrows; teeth lateral margin sharply denticulate. D. (C.) Iredale, Iredale virilis — 1930. Shell Donax Section scarcely s. Shell s. strong, posteriorly very short, anteriorly long, with simple radial furrows; anterior lateral tooth long; rugosus Linne (Fig. 845). margin sharply denticulate. D. ventral — Section Grammatodonax Dall, (£>.) 1900. Shell short triangular; surface with deep oblique furrows; right valve with a cleft main one with 2 simple main teeth and an anterior tooth; the left and posterior lateral tooth; madagascariensis Lamarck. margin finely denticulate. D. (G.) ventral — Hecuba Schumacher, 1817. Section large, posteriorly with a sharp keel Shell ending in an acute angle, anterior to with concentric threads and lamellae; hinge teeth similar to those in it Serrula; anterior dorsal margin of the right valve with a distinct furrow; ventral — margin with very fine transverse wrinkles. D. Section Serrula (Chemnitz) Morch, 1853. Shell (//.) smooth, without posterior keel, 2 main teeth on either with weak D. (S.) lateral teeth; ventral trunculus Linne. — scortum Linne. compressed, long, side; on the left margin sometimes only weakly denticulate. Section Platydonax Dall, 1900. Shell long, compressed, without distinct keel; hinge teeth similar to those in Serrula, — 907 but without lateral teeth. D. (P.) finchii Sowerby. Section Machaerodonax E. Romer, 1870. Shell smooth and shiny, thin, long and low, posteriorly with a sharp keel; hinge margin on the right with a weak tooth posterior to furrow; — ventral the 2 normal teeth; Section Plebidonax Iredale, triangular, with teeth distinct; anterior dorsal 1930. Shell large and strong, unequally rounded edge; surface finely radially sculptured; right anterior dorsal smooth. D. (P.) deltoides Lamarck. — 1887). P. Fischer, posteriorly not Section Latona Schumacher, 1817 Shell distinctly truncated; compressed, rounded surface posteriorly sometimes rough sculpture; left valve with 2 a weak lateral margin furrowed; ventral margin (synonym Liodonax triangular, margin with a margin finely denticulate. D. (M.) scalpellum Gray. with main weak, teeth and posterior lateral tooth; the right one with one strong and one rudimentary anterior main tooth, as well as one anterior and posterior lateral — tooth; ventral margin not denticulate. D. (L.) cuneatus Linne. Section Tentidonax Iredale, 1930, appears to be intermediate between Latona and Capsella. D. Lamarck). — Section (T.) veruinus Hedley (= nitidus Reeve non Capsella Gray, Morch, 1853). Shell long and low, 1851 thin, (synonym Peraeonoderma smooth, without posterior edge; 1375 on the left with a short anterior lateral tooth just anterior to the 2 main teeth and a longer marginal posterior lateral tooth; on the right the posterior main tooth is cleft, anterior and above the anterior one lies a short lateral tooth and the anterior dorsal margin politus (Poli) is furrowed. D. (C.) = violaceus (Meuschen). Iphigenia Schumacher, 1817 Synonyms Capsa Lamarck, 1818, non 1799; 1821; Procos Gistel, Shell fairly ? Donacina Ferussac, 1848. thin, elliptical to with yellowish or olive- triangular, brown periostracum, without sculpture; umbo close to the center; ligament main teeth, the right with one strong, main tooth and with long and anterior one weak and cleft main tooth mantle sinus deep. Siphons lateral teeth; posterior and narrow anterior external, short; left valve with 2 long, free, exteriorly with longitudinal threads; and with terminal papillae; gill laminae palps long. free; labial A few species on the coast and in rivers of both coasts of Central and South America. Section Iphigenia violet flecks, Gmelin]. — mainly s. s. in tropical West Africa and Shell medium-sized, interiorly with white or brackish water. /. Section Profischeria Dall, 1903 (/.) laevigata [(Chemnitz) (synonym Fischeria Bernardi, 1860, non Robineau-Desvoidy, 1830). Shell small, interiorly violet, mainly in rivers. /. (P.) delesserti Bernardi. Egeria Roissy, 1805 Synonym Galatea 1822; Bruguiere, 1797 1793; Potamophila Fabricius, J. = Galathea Lamarck, 1804, non Sowerby, 1821; Megadesma Bowdich, Galateola (Fleming) Herrmannsen, 1847. Shell thick, triangular to longish, with strong periostracum; margin broad, with 2 or and on the right with which are often 3 often irregularly low and short anterior and posterior indistinct in old shells; hinge furrowed diverging main teeth lateral teeth, mantle sinus moderately deep, rounded. E. West radiata (Lamarck). A few species, in brackish water of tropical Africa. 908 2. Family PSAMMOBIIDAE Shell equivalve, oval or elongated, external, on thick ridges; hinge smooth or sculptured; ligament margin as a rule with 2 main teeth on 1376 muscle scars close either side, without lateral teeth; to the dorsum; mantle sinus deep, often continuous with the ventral mantle line; lower margin smooth. Mantle margin widely open, with papillae; siphons very long and foot tongue-shaped, without byssus; separate; gill laminae folded with larger inner border filaments; outermost lamella broadened; oral lobes large, triangular. Heterodonax Morch, 1853 Shell compressed, oval, anteriorly somewhat longer than posteriorly, and posterior right hinge exteriorly only with growth lines; anterior left tooth cleft, left posterior one weak; mantle sinus broad, roundish, separated from the mantle line. H. bimaculatus (Linne). Few species, on American coasts. Asaphis Modeer, 1793 Synonyms Corbula (Bolten) Roding, 1798; Capsa Lamarck, 1801, non 1799; Capsula Schumacher, 1817; Pleiorhytis Conrad, 1863. Shell large and strong, oval, bulging, with slender radiating umbo somewhat anterior left and posterior situated thick; anterior weak; mantle sinus Few Section Asaphis — ? A. species, in warm s. s. Martens, contraria (Deshayes). According — is to line. radial. A. (A.) deflorata (Linne). 1880. This group Ribs converging in angles. is in most cases placed Psammobia. Bolten and ones seas. Ribs uniformly Section Heteroglypta (//.) right tooth furrowed, the 2 other rounded, separated from the mantle large, ribs; to the center; ligament fairly long Winckworth, 1930, Corbula Roding — sp. typ. in anomala synonymous with Asaphis. Elizia Gray, 1854 Shell thin, greatly compressed, with strong periostracum, oval; umbo not projecting, close to the anterior end; hinge margin very narrow, on the left with 3 teeth, the on the right median of which is very broad and furrowed, with 2 widely diverging teeth; mantle sinus completely separated from the mantle line. E. Islands. orbiculata (Wood), near Indochina and the Greater Sunda — 1377 Sanguinolaria Lamarck, 1799 Synonyms Aulus Oken, 1815; Lobaria Schumacher, 1817, non Miiller, 1776;/wc/iaGistel, 1848. Shell oval more elongated, compressed, smooth; umbo only or on situated close to the center hinge margin weak, slightly projecting, either side with 2 unequal teeth; mantle sinus deep, ventrally not or only from the mantle slightly separated A few species, Section somewhat Nuttallia flatter Dall, than the (N.) valve umbo Shell somewhat fairly large, oval; anterior to the center; ligamental mantle sinus posteriorly very broad, anteriorly narrowed. ridges broad; S. right with strong, smooth periostracum; 1898. left, scarcely projecting, situated 909 line. in various seas. Conrad. nuttallii Section Psammotellina P. Few near Japan and California. species, Fischer, only slightly elongated, 1887. Shell greatly compressed; ligamental ridges with broad, more or less excavated roughenings; right posterior hinge tooth rudimentary; mantle sinus long and narrow. S. (P.) ambigua (Deshayes). — Section Solenotellina Blainville, 1824 (Soletelllina) (synonym Hiatula Modeer, 1793, non Martini, 1774). Shell more equivalve, large, fairly or less teeth on either side; diphos (Gmelin). Psammocola fairly strong hinge margin with 2 mantle sinus very deep, anteriorly narrowed. —Section Blainville, long and projecting; 5". (5.) Psammotaea Lamarck, 1818 (synonyms 1824; Capsella Deshayes, elongated oval, concentrically striated; Shell 1851). with elongated, periostracum; ligamental ridges short and broad; 1854, non Gray, ligamental ridges posterior hinge tooth rudimentary. S. (P.) left serotina Lamarck. Psammosphaerita Jousseaume, 1894 (psammosphaerita Jousseaume) s. 2 cleft Shell s. red, or white, with with from Psammotaea by the nongaping differs Sanguinolaria — Section Herrmannsen, 1852. Shell long, beaked; the two shell. — Section equivalve, oval, rose- mantle sinus deep, anteriorly widened. (Gmelin). hinge as in Sanguinolaria in thin, narrow ligamental ridges; hinge margin on either side teeth; sanguinolenta moderately sized, s. s.; Psammotella left S. (S.) (Blainvelle) valve flatter than the right; mantle sinus anteriorly narrowed, unequal valves. S. (P.) operculata (Gmelin). Psammobia Lamarck, 1818 Synonym Haplomochlia Gistel, 1848. Shell more or less long, smooth or anteriorly striated, somewhat gaping, rounded, posteriorly in most cases somewhat flattened or angulate; hinge margin on either side with 2 teeth, of which the left and 1378 the anterior right ones are cleft; fused with the mantle umbo not projecting; mantle sinus largely Siphons very long and line. thin. Several species, in various seas, living close to the shore. Subgenus Gobraeus Leach, 1852. Shell somewhat bulging, posteriorly more or less truncated, smooth or concentrically striated; umbo close to more or less deep and often the center; hinge teeth variable; mantle sinus partly detached (Fig. 846). — ? from the mantle line. P. Section Psammobella Gray, 1851. weak; mantle sinus connected with the mantle (Gmelin) vespertina (G.) Shell P. line; small; (P.) hinge tellinella Lamarck. Fig. 846. Inner side of the right shell valve of Psammobia (Gobraeus) vespertina (Gmelin). Subgenus Psammobia pointed, s. s. Shell long, posteriorly more or less with concentric or oblique sculpture; mantle sinus largely connected with the mantle line. concentrically sculptured. P. Grammatomya Section Psammobia (P.) feroensis s. s. (Gmelin). Surface —Section Dall, 1898. Shell with oblique, posteriorly strengthened and scaly ridges; hinge margin on either side with 2 teeth; mantle sinus short, rounded, anteriorly detached from the mantle line. P. (G.) squamosa Lamarck. The genus name Gari Schumacher, 1817, hardly be used, since gari spice used by Romans, a is fact was a sharp presumably not known to Schumacher. Amphichaena 910 for Tellina gari Linne, can the genitive of the garum, which Philippi, 1847 Shell elongated; dorsal and ventral margins nearly parallel; anterior end rounded; posterior end truncated; umbo situated in the center; surface smooth; ligamental ridges short and thin; hinge margin on the right with 2 partly free; A. on the left with 3 teeth; mantle sinus rounded, ventrally anterior margin interiorly crenated. kindermanni Philippi, near Mazatlan (Mexico). 1379 Tagelus Gray, 1847 Synonyms Siliquaria Schumacher, 1817, non Bruguiere, 1789; Tagalus P.Fischer, 1887. Shell elongated; dorsal and ventral margins nearly parallel, the ends rounded or somewhat truncated; hinge margin on either side with 2 teeth. Anterior mantle opening long, closed only at the cross-shaped muscle; siphons long and separate; foot large. Few on American species, coasts. Subgenus Mesopleura Conrad, 1867 (synonym Subtagelus Ghosh, umbo 1920). Shell thin; side with a weak rib situated nearly in the center; ends rounded; inner descending from umbo; mantle sinus moderately deep, rounded, not separated from the mantle Subgenus Clunaculum anterior end; Dall, 1899. posterior end truncated; line. T. Umbo in (M.) divisus (Spengler). the rounded closer to the center with an oblique furrow corresponding to an internal thickening; mantle sinus not reaching the umbones; posterior adductor muscle scar triangular. T. (C.) mollis (Sowerby). Subgenus Tagelus furrow; exterior roundish. T. (T.) s. s. Umbo at or posterior to the center, without mantle sinus deep; posterior adductor muscle scar gibbus (Spengler) (Fig. 847). 847. Inner side of the right shell valve of Tagelus gibbus (Spengler). Fig. length 6.5 cm. Solenocurtellus Ghosh, Shell elongated; gaping; surface with reaching the center. common S. umbo 1920 (Solecurtellus) close to the center; both ends rounded and strong, smooth periostracum; mantle sinus not Mantle margins fused only posteriorly; a short space anterior to the siphons. dombeyi (Lamarck), on the west coast of South America. Zozia Winckworth, 1930 Synonym Azor (Leach) T. Brown, 1844, non Sowerby, 1824. 1380 Shell fairly small and thin, moderately long, anteriorly and posteriorly umbo gaping; somewhat situated anterior to the both ends center; rounded; surface with somewhat lamellose periostracum, with concentric growth mantle sinus broad, rounded. Mantle margin anteriorly with lines; tentacles, posteriorly closed, anterior to the siphons with a short on either side on the mantle, part with ridge to which the common bases gill adjoin. Z chamasolen (Da Costa) = antiquata (Donovan), in European seas. Solenocurtus Blainville, 1825 (Solecurtus) 911 Synonyms Psammosolen Risso, 1826; Macha Oken, 1835; Cyrtosolen Herrmannsen, 1848; Adasius Leach, 1852. Shell moderately long; umbo anterior to the situated ends rounded and gaping; surface with oblique either side with 2 teeth; mantle sinus large, extending center; both hinge margin on lines; beyond the center. Mantle anteriorly open, without tentacles, posterior half closed; anterior to the siphons with a large common portion; foot very large; labial palps narrow, triangular. strigillatus (Linne). S. main lateral teeth; teeth; more or in various seas. SEMELIDAE most cases roundish or in ridges, with an interior, to the few species, Family 3. Shell A oval; ligament not on projecting less strong cartilage situated posterior hinge margin as a rule with 1 or 2 main teeth and mantle sinus posteriorly narrowed. Animal with long, completely separated siphons; mantle widely open below; foot large, without byssus; labial palps large; outer gill lamina narrow, upwardly without reflected lamella; in most cases the directed, gill laminae are smooth. Semele Schumacher, 1817 Synonym Amphidesma Lamarck, Shell gaping, roundish or often strong; sometimes posterior more or less to elliptical, umbo situated and posteriorly somewhat sometimes somewhat anterior, the center, only slightly elevated; strong concentric ligament small; 1818. anteriorly cartilage in and weaker radial surface with sculpture; external an oblique pit which does not project inwardly; anterior to this on either side with 2 small main teeth, on the right with distinct, on the left with weaker anterior and posterior lateral 1381 teeth; muscle scars large; mantle sinus elliptical, and completely separated from the mantle warm Several species, in Section Semele weak. s. S. weak sculpture; proficua (Pulteney) (Fig. (5.) anteriorly umbo 1900. Dall, Shell small, 848). — — umbo close Section Semelina with dense concentric sculpture; M/cw/a-like, cleft, posterior one rudimentary; left nuculoides Conrad. lateral teeth indistinct. S. (S.) _ A __ Fig. on the Section Elegantula [(Ruppell Reeve]. main tooth close to the teeth; lateral teeth Gregorio, 1884. Shell with fairly broad concentric lamellae; to the anterior end. S. (E.) striata cartilage short; anterior left ascending laminae folded. Gill seas. Shell with margin on either side with 2 main center; hinge left s. line. — ap 848. Inner side of the right shell valve of Semele Jlavescens Gould, aa, ap. anterior and posterior adductor muscle; Punigapia I, ligamental cartilage. 1930 Iredale, Shell small and thin, oval, white or purplish; umbo scarcely elevated, closer to the posterior end; ligamental cartilage weak, very oblique, not projecting inwardly; right valve with 2 main teeth and distinct lateral teeth; left valve with 2 dissimilar main teeth; mantle sinus not very deep, anteriorly flattened, free to about one-half. P. subelliptica (Sowerby), near eastern Australia. Semelangulus Shell small, 1924 white or pink, anteriorly elongated and rounded, posteriorly obliquely truncated; weak; cartilage Iredale, thin, surface concentrically striated; ligament interiorly not projecting, oblique; right valve with 1382 2 main teeth and 2 fairly long lateral teeth; left valve with one main tooth; mantle sinus nearly reaching the anterior adductor muscle S. tenuiliratus (Sowerby), near eastern Australia scar. and the Fiji Islands. Cumingia Sowerby, 1833 Synonyms Harpax Meyer, Shell umbo Gistel, 1848, non Parkinson, 1811; Mikrola O. 1887. somewhat triangular, anteriorly rounded, posteriorly angulate; only slightly projecting; ligamental cartilage large, somewhat posteriorly inclined and interiorly projecting, anterior to it on either side with a weak main tooth; lateral teeth of the right valve large, those of the left valve weak or with the mantle C. mutica absent; mantle sinus very deep and broad, joined line. Few American Sowerby. species, living in holes of rocks. Eumontrouziera Hedley, 1915 Synonym Montrouzieria 1863, non Montrouziera Bigot Souverbie, 1860. Shell longish, posteriorly shorter, angulate, anteriorly bulging, straight below; surface with radial and concentric threads; cartilage narrow triangular, main obliquely posteriorly directed and interiorly projecting; teeth anterior to triangular; on the it left on the right, the anterior of which is 2 thick and a triangular tooth, on both sides one posterior muscle scar narrow; mantle sinus deep, joined with lateral tooth; anterior the mantle line. E. clathrata (Souverbie), near Thyella H. Shell somewhat New Caledonia. Adams, 1865 triangular, posteriorly somewhat shorter and flattened, with concentric threads or lamellae and fine radial lines; ligamental bands obliquely interiorally projecting; Eumontrouziera; lateral teeth absent; from the mantle T. main teeth similar to those in mantle sinus broad, partly separated line. pulchra H. Adams. Few Theora H. species, in the Indo-Australia region. & A. Adams, 1856 Shell thin and translucent, compressed, elongated oval, smooth and shiny, posteriorly or also anteriorly gaping; ligamental cartilage oblique, 1383 interiorly projecting, on the left and thin lateral teeth of the right valve; mantle sinus deep. main teeth Few lata (Hinds). T. species, mainly near Japan to Australia. Endopleura A. Adams, anteriorly-descending Souleyetia with one, on' the right with 2 very small 1 864 (lubrica Gould), interiorly has an oblique rib. Recluz, seems 1869, reduction of the hinge teeth. to differ from Theora only by moulinsi Recluz, near Borneo. S. Abra (Leach) Lamarck, 1818 Synonym Syndosmya Recluz, 1843 somewhat longer than = Syndesmia somewhat Shell thin, colorless, oval or umbo posteriorly; L. Agassiz, 1846. triangular, often anteriorly only slightly projecting; external ligament weak; cartilage interiorly only slightly projecting, anterior to the left with 1, on the right 2 and posterior thin anterior weak main lateral tooth; narrowed, joined with the mantle A few species, Subgenus Abra Shell it on teeth; in the right valve with an mantle sinus posteriorly greatly line. in various seas. s. s. (synonyms Orixa + ? Dorvillea Leach, 1852). smooth or weakly concentrically sculptured, somewhat triangular or oval. A. (A.) tenuis (Montagu); Monterosato, 1884, proposed a group species (ovata Philippi), and Iredale, 1924, proposed a "genus" Abranda for the Australian A. rex Iredale = elliptica Lulricularia for the oval (Sowerby). Subgenus Iacra H. 1861). & A. Adams, 1856 (synonym Strigillina Dunker, Shell with angle-shaped sculpture; hinge margin on either side with a small main tooth and with lateral teeth, which are stronger on the right. A. (/.) seychellarum (A. Adams). Scrobicularia Schumacher, 1817 Synonyms Arenaria Megerle von Muhlfeld, 1811, non 1760; Listera Turton, Shell Brisson, 1822. compressed, oval, posteriorly somewhat angulate; external ligament small; cartilage triangular, only slightly interiorly projecting; on the left with mantle sinus 1, on the right with 2 small main teeth, without large, joined with the mantle line. Gill lateral teeth; laminae smooth. Subgenus Leptomya A. Adams, 1864. Shell somewhat bulging and posteriorly pointed. S. (L.) cochlearis (Hinds). Australian region and near New Zealand. Few species, in the Indo- 1384 Subgenus Scrobicularia s. s. Shell flattened, oval. S. (S.) plana Costa). 2 European species. S. ceylonica Edg. Smith does not (Da seem to belong here. Family 4. TELLINIDAE most cases oval, sometimes elongated and posteriorly rostrate, somewhat asymmetrical, externally smooth or variably sculptured; ligament external, in the right valve in most cases with lateral teeth in addition to the main teeth; mantle sinus large, often more or less joined with the mantle line, occasionally differing on the two sides. Siphons Shell in often separate; gill laminae smooth, the outer upwardly directed, sometimes very small; labial palps large; foot sometimes with a sole and a small byssal groove at the posterior end. Arcopagia (Leach) T. Brown, 1827 Synonym Cydippe Leach, 1852, non Eschscholtz, 1829. most cases with concentric sculpture; umbo very slightly projecting; hinge margin with 2 main teeth on either side, one of which is furrowed, and with lateral teeth, of which the posterior one Shell of the left oval, in may be side joined with the mantle A few species, in absent; mantle sinus freely ascending or partly line. warm Subgenus Arcopagia 914 s. seas. s. Shell moderately bulging, roundly oval, mantle sinus free. Section Arcopella sched. Shell fairly small and weak; anterior end only concentrically sculptured; Monterosato, in weak slightly longer than the posterior; lateral teeth fairly long, left valve. A. fairly large (A.) balaustina (Linne). and strong, anteriorly — Section Arcopagia s. s. in the Shell distinctly longer than posteriorly; left posterior lateral tooth rudimentary. A. (A.) crassa (Pennant). Subgenus Elliptotellina oval, anteriorly Cossmann, 1886. Shell small, bulging, longish and posteriorly rounded; the concentric sculpture ends often crossed by radial lines; left lateral teeth absent; at the mantle sinus obliquely ascending. A. (E.) tellinella (Lamarck) f; Dall described free, a couple of living species from American coasts. Maoritellina Finlay, 1927, may be a related group, whose typical New Zealand species charlottae (Edg. Smith), according to Finlay, has a short, free, steeply ascending mantle sinus. Subgenus Pinguitellina short triangular, Iredale, 1927. Shell small, strongly bulging, with concentric threads; left lateral teeth present; 1385 mantle sinus partly continuous with the mantle A. line. robusta (P.) (Hanley). Subgenus Arcopaginula Jousseaume, 1918. colorless, posteriorly with a flattening delimited left valve more strongly bulging; medium-sized, Shell by an edge, asymmetrical; anterior lateral teeth fairly short, posterior ones long, those of the left valve weak; mantle sinus partly joined with the mantle line. A. (A.) inflata (Chemnitz). Strigilla Turton, roundish, bulging; Shell somewhat angular, scarcely elevated, anterior to the center, with oblique sculpture surface; entire umbo 1822 on a situated part or the lunule narrow, asymmetrical; ligament small and weak; hinge margin on the right with 2 main teeth and 2 moderately long teeth, on the left lateral with one main tooth and 2 weak lateral teeth; mantle sinus not separated from the mantle line. A few species, in warm seas. Section Rombergia Dall, 1900. which form angles anteriorly and The entire surface with oblique lines, posteriorly; mantle sinus equal sides, not reaching the anterior adductor Morch. — Section Strigilla s. s. — scar. S. on both rombergi (/?.) Surface sculptured as in Rombergia; mantle sinus not completely symmetrical. sections near America. muscle S. (S.) carnaria (Linne). Both Section Aeretica Dall, 1900. Surface with more or less strong concentric sculpture and on the larger posterior half with oblique lines; mantle sinus greatly differing on the two sides, on the left almost or fully reaching the anterior adductor muscle scar, considerably shorter on the right. S. (A.) Philippines, Java, senegalensis (Hanley). Sandwich Islands, Few species, near the and Senegambia. Pseudarcopagia Bertin, 1878 Shell roundish oval, medium-sized, moderately bulging, posteriorly somewhat asymmetrical, with concentric and weaker ligament fairly long; anterior weaker on the mantle left lateral teeth shorter radial sculpture; than the posterior ones, than on the right; mantle sinus largely joined with the line. Section Pseudarcopagia s. s. Surface distinctly latticed. P. (P.) decussato (Lamarck) = victoriae (Gatliff & Gabriel). A couple of Australian species. — Section Zearcopagia and more finely sculptured. P. Zealand. (Z.) Finlay, 1927. Shell disculus (Deshayes), smaller near New 1386 Cossmann, 1886 Cyclotellina Shell large and strong, roundish, inequivalve; ligament large; left valve without distinct lateral teeth; mantle sinus partly joined with the mantle line, anteriorly impressed angulate and joined with the anterior muscle scar Subgenus Cyclotellina radial sculpture; (Deshayes) the West by an line. f. and weak Shell with distinct concentric s. s. anterior lateral right tooth short. C. (C.) lunulata Dall included here the Recent species fausta (Pultney) from Indies and remies (Linne) and discus (Hanley) from the Indo- Australian region. Subgenus Scutarcopagia Pilsbry, 1918. Shell nearly circular, with small warts which are joined with one another more or less net-shaped; right anterior lateral tooth fairly long. C. (S.) scobinata (Linne), in the Pacific Ocean. Apolymetis Salisbury, 1929 Synonyms non ? Capsa Bruguiere, 1797; Metis H. 1843, nee Gistel, Philippi, & A. Adams, 1856, 1848; Polymetis Salisbury, 1929, non Walsingham, 1903. Shell thin, colorless, oval, with a narrow depressed lunule, in the posterior part asymmetrical and folded; surface with concentric threads; ligament strong; hinge margin on either side with 2 unequal main teeth, the larger of which is cleft; completely or largely Few species, in mantle sinus more or less steeply ascending, free. warm Subgenus Hemimetis seas. Right valve with a thin lateral tooth n. posterior to the ligament and a lunule; mantle sinus largely weak one below free, the anterior part of the obliquely ascending. A. (//.) plicata lateral teeth; mantle (Valenciennes). Subgenus Apolymetis sinus free, Iredale, more or s. s. Right valve without less steeply ascending. A. (A.) meyeri (Dunker). 1930, proposed a genus Leporimetis for the posteriorly steeply descending Tellina spectabilis Hanley, the mantle sinus of which is largely joined with the mantle line; it appears between Apolymetis and Macoma, but closer to the to be intermediate latter. Gastrana Schumacher, 1817 Synonyms Diodonta Deshayes, 1846; Fragilia Deshayes, 1848. Shell bulging, fairly thin, oval, posteriorly elongated, with concentric 1387 threads and weak weak; hinge margin on the right radial lines; ligament with 2 greatly diverging main teeth, on the with 2 dissimilar main left without lateral teeth; mantle sinus moderately deep, rounded, teeth; scarcely ascending, free. G. fragilis (Linne). Few species, in various seas. Macoma Synonym Limicola Leach, Shell shorter, in most cases flattened Leach, 1819 1852, non Koch, 1816. somewhat fairly thin, without lateral teeth; mantle sinus partly Numerous Subgenus triangular, and folded; surface with growth lines; posteriorly hinge margin free. species, in various seas. Macoma distinct periostracum; s. Shell anteriorly moderately elongated, with s. mantle sinus often differing in the two valves. M. = calcarea (Gmelin). Mainly (M.) tenera Leach in the colder northern seas. Subgenus Salmacoma 1929. Iredale, inequivalve, Shell anteriorly only slightly elongated, thin; hinge teeth small, on the right with only one; mantle sinus differing on the two sides. eastern M. (5.) vappa (Iredale), near Australia. Subgenus Macalia H. Adams, 1860 (synonym Tellinungula Romer, 1872). Shell anteriorly only strikingly large teeth. M. (A/.) slightly longer; warm bruguieri (Hanley). In Subgenus Rexithaerus Conrad, 1869. Shell seas. large, inequivalve, margin distinctly elevated and gaping posterior E. hinge margin with smooth; somewhat to the strong, sunken ligament. Subgenus Psammacoma 1900. Dall, Shell anteriorly longer and rounded, posteriorly truncated, smooth; the two valves only slightly different. Psammacoma Section s. Shell s. anteriorly significantly elongated, thin; ligament completely external; mantle sinus moderately deep. M. Candida (Lamarck). (P.) 1918. Shell fairly strong, pallial sinus Dall, different; in 1921. Shell Section Pseudometis Jousseaume, thin, ligament somewhat sunken; anteriorly the anterior part with ligament short; mantle sinus largely adductor muscle scar. M. section — triangular; moderately deep. M. (P.) truncata (Jonas). Temnoconcha slightly more (T.) free, oblique impressed lines; reaching almost to the anterior brasiliana Dall. Dall, Cydippina for M. brevifrons Say, but discarded it. — Section Psammotreta Dall, —Section and posteriorly only 1900, proposed a later seems to have 1900. Shell moderately long, with an internal cartilage, partly separated from the ligament. M. (P.) aurora (Hanley). 1388 Subgenus Tellinimactra Jousseaume, 1918. Shell thin, bulging, hinge teeth weak; greatly elongated; anteriorly not smooth ligament short, sunken; mantle sinus deep, largely joined with the mantle line, anteriorly almost reaching the narrow anterior adductor muscle scar. M. (T.) edentula (Spengler). Subgenus Cymatoica Dall, 1889. small and very thin, with Shell wrinkled folds; posterior end oblique. M. (C.) undulata concentric (Hanley). Tellidora (Morch) H. & A. Adams, 1856 Shell colorless, thin, compressed, inequivalve, triangular, concentrically sculptured; lunule and ligamental surface narrow, with elevated, denticulate margins; ligament short; right valve with 2 main teeth and 2 long lateral teeth; left valve with one main tooth; margin; mantle sinus T. lateral teeth not separated from the free. & bumeti (Broderip Few Sowerby). species, in warm seas. Merisca Dall, 1900 Shell colorless, fairly small, distinctly more or less triangular, in inequivalve, posteriorly truncated or with concentric lamellae and often fine radial lines; umbo most cases short beak, with close to the center, not projecting; right valve with distinct elongated lateral teeth; mantle sinus large, completely joined with the mantle line. Subgenus Merisca weak radial sculpture. s. s. Shell M. (M.) more or crystallina less distinctly beaked, (Wood). A with few American species and one from Singapore. 917 Subgenus Clathrotellina n. Shell nearly equivalve, posteriorly somewhat pointed, with numerous fine radial threads, whose point of intersection with the concentric threads bear small (C.) pretiosa (Deshayes), near the Philippines. elevated scales. M. The Californian M. reclusa (Dall) seems to be intermediate between the two subgenera. Quadrans (Klein) Shell rounded; medium-sized, umbo in fairly most cases weak strong, most cases close narrow depressed lunule anterior radial Berlin, to 1878 rounded triangular, anteriorly to the center, it; scarcely elevated, a surface with concentric and in sculpture; ligament external, fairly long; hinge margin on either side with 2 main teeth, the stronger of which is furrowed, and an anterior and posterior lateral tooth, which in the left 1389 valve are not separated from the margin; mantle sinus large, nearly reaching the narrow anterior adductor muscle scar. Few species, mainly in the Indo-Pacific region. Section Striotellina longish triangular, with dense concentric n. Shell threads, which posteriorly become coarser and more irregular and at the edges of the depressed ligamental surface form irregular cusps; radial mantle sinus nearly reaching the anterior sculpture scarcely indicated; adductor muscle scar, in its posterior half separated from the mantle line a very narrow interval. Q. (S.) serratus (Renieri), in the Mediterranean by Sea and the neighboring Atlantic Ocean. Umbo 1929. the posterior end; closer to — Section Obtellina surface with fine, Iredale, oblique, anteriorly ascending lines, in the posterior part with irregular wrinkles, which form cusps mantle line. the margin; mantle sinus largely joined with the at New Q. (O.) bourgei (Sowerby), near Caledonia. obtusalis Deshayes, also placed by Iredale in Obtellina, — Section Quadrans s. s. is Tellina very different. Ligamental surface depressed, with cuspidate margins; surface with somewhat oblique threads which are in most cases wrinkled in the posterior part; radial lines indistinct; mantle sinus almost completely joined with the mantle — line. (Q.) gargadia Q. (Linne). Section Pistris n. nom. (synonyms Pristis (Jousseaume, Lamy, 1918, non Latham, 1794, nee Muller surface depressed, & Henle, somewhat wavy threads and surface with fine radial impressed lines; Q. (P.) pristis (Lamarck). free. 1837)). Shell relatively high; ligamental with cuspidate margins; — concentric, mantle sinus partly Section Quidnipagus Iredale, 1929. Shell somewhat beaked; lunule and area very narrow, somewhat asymmetrical; surface with wavy or cuspidate discontinuous wrinkles and posteriorly fine radial furrows; mantle sinus free in about one-half. Q. (Q.) palatum (Martyn) = rugosus (Born). Homalina Stoliczka, 1871 Shell compressed, triangular, anteriorly rounded, posteriorly pointed and somewhat asymmetrical, externally smooth and colorless; umbo not elevated, closer to the anterior end; hinge margin on either side with 2 main lateral teeth and on the right with a short anterior and a weak posterior tooth at the end of the ligament; mantle sinus deep, completely joined with the mantle adductor muscle line, Subgenus Homalina lateral tooth almost or fully reaching the narrow anterior scar. s. s. Shell thin, shiny; hinge line weak; anterior very short, occasionally joined with the anterior main tooth; posterior lateral tooth posterior to the end of the ligament; mantle sinus 1390 918 asymmetrical, on the right reaching the anterior adductor muscle scar, H. (//.) triangularis (Chemnitz), in the Indian Ocean. Subgenus Macomona Finlay, 1927. Shell fairly strong; anterior lateral tooth distinctly separated from the main teeth; mantle sinus on both sides reaching the ventral end of anterior adductor muscle scar. H. (M.) liliana New (Iredale), near Zealand. Phylloda Schumacher, 1817 Shell thin, greatly compressed, longish, anteriorly rounded, posteriorly umbo obliquely truncate and somewhat asymmetrical; close to the center; long and thin; mantle sinus short, ascending, largely Subgenus Phyllodina threads, the ends of not projecting, ligament surface finely concentrically sculptured; free. Dall, 1900. Shell small; surface with concentric which form tooth-shaped lamellae on the sides of the very narrow lunule and ligamental surface; lateral teeth of the right valve distinctly developed, fairly long. P. (P.) squamifera (Deshayes), near America. Subgenus Phylloda s. s. sculpture, the posterior part, tubercles and denticulate Shell which large, fairly is with fine and dense delimited by an edge, with small on the dorsal margin; lunule and ligamental surface extremely narrow; lateral teeth indistinct; a short anterior one of the right valve joined with the anterior main tooth; anterior corner of the mantle sinus joined with the anterior adductor muscle scar through a weak depression. P. (P.) foliacea (Linne), in the Indo-Pacific region. Eurytellina P. Fischer, 1887 Shell compressed, fairly long, posteriorly somewhat pointed and only slightly asymmetrical, weakly concentrically sculptured; projecting, close to the center; ligament fairly long anterior lateral the anterior main to.oth and umbo thin, not not sunken; of the right valve very short and close to tooth, the posterior one below the end of the ligament; mantle sinus joined with the mantle line, almost reaching the anterior adductor muscle scar, posterior to which runs a radial thickening. E. punicea (Born), in warm seas. may be a subgenus of Scrobiculina Dall, 1900, shell is weakly sculptured; ligament with anterior lateral tooth short, the posterior deep, joined with the mantle line. Eurytellina; the thin short, internal cartilage; right one weak; mantle sinus moderately 1391 S. A viridotincta (Carpenter). couple of Califomian species. Angulus Megerle von Muhlfeld, 1811 Shell more or compressed, in most cases less elongated, fairly small, posteriorly angulate and only slightly asymmetrical; ligament short; hinge margin in most cases on the right with a short anterior lateral tooth; mantle sinus not separated from the mantle line. Several species, in Subgenus Moerella Adams, 1856, non 1812). warmer P. seas. & A. 1816; Donacilla Gray, 1851, non Lamarck, Hiibner, and rounded, posteriorly obliquely anteriorly elongated Shell 1887 (synonyms Moera H. Fischer, truncated; surface finely concentrically striated; right valve with a short one below the end of ligament. anterior lateral tooth and a posterior A. (A/.) donacinus (Linne). Subgenus Fabulina Gray, 1851. Shell small and moderately elongated, most cases thin and transparent; a in Section Scissula Dall, 1900. Shell right posterior lateral tooth absent. similar to Moerella, but with fine oblique striae on the surface and without posterior lateral tooth. A. (S.) decorus (Say). — center; posterior Section Fabulina s. s. end pointed; only the Shell thin; umbo close to the right valve sculptured with fine oblique lines; anterior lateral tooth short. A. (F.) fabula (Gronovius), in the Mediterranean Sea and eastern Atlantic Ocean. Monterosato, 1884. Shell thin, greatly compressed; posterior end; Section Oudardia umbo closer to the surface with gradually ascending oblique lines, which leave the posterior part free, posterior to — the in the interior with anterior adductor muscle somewhat away from the main scar; teeth. A. (O.) a radial thickening anterior lateral tooth compressus (Brocchi), in the Mediterranean Sea, and one species (buttoni Dall) from California. — Section Exotica Jousseaume, 1918. Shell very similarly formed and sculptured to that in Oudardia, but without anterior lateral tooth and without internal ridge-shaped thickening. A. (E.) rhomboides (Quoy Gaimard), in the Indo-Pacific region. Shell fairly short oval, posteriorly — & Section Jactellina Iredale, 1929. somewhat flattened; surface with fine oblique lines, which leave only the posterior part free; the posterior of the 2 left main in teeth of the right valve is sometimes rudimentary, also on the most cases only one well developed tooth; lateral teeth absent. A. (J.) obliquarius (Deshayes), from Polynesia. Subgenus Tellinangulus n. Shell small, anteriorly rounded, posteriorly with short beak and distinctly asymmetrical, with concentric, not very densely placed threads, the intervening spaces of which are finely radially striated; left anterior and right posterior main tooth cleft; right 1392 anterior main tooth very aethiopicus (Jackel & short, joined with the anterior Subgenus Angulus s. compressed, concentrically Angulus absent. Section s. s. Shell s. medium-sized, longish, greatly Shell long and fairly low; umbo Section from the main Lamarck, short or close to the teeth. A. Shell only slightly anterior to the center; anterior lateral close to the anterior tooth — — umbo 1818. lanceolatus (Linne). elongated oval; tooth. A.{T.) right anterior lateral tooth striated; center; anterior lateral tooth distinctly separated (A.) main Thiele), near East Africa. Section main Tellinides A. tooth. timorensis (Lamarck). (T.) Homala Schumacher, 1817 (Omala). Shell anteriorly short and posteriorly greatly elongated; right anterior lateral tooth very short and close to the anterior shaped thickening main tooth; anterior to present. A. is it in the left valve a bulge- hyalinus (Gmelin). (//.) —Section Peronidia Dall, 1900 (synonym Peronea (Poli) Morch, 1853, non Peronea 1824, nee Peronia Blainville, Curtis, umbo pointed to blunt; teeth. A. lateral situated (P.) albicans in 1824). Shell longish, posteriorly hinge margin without the center; (Gmelin) = nitidus (Poli). Tellina Linne, 1758 Synonyms Shell Tellinella fairly large, Morch, 1853; Eutellina asymmetrical, anteriorly rounded; as a rule on the right with 2 main teeth; main teeth; right valve with Section Tellina s. concentric sculpture. P. — Fischer, long 1887. s. warm with one, on the away from seas. T. (T.) virgata Linne (Fig. 849). Surface smooth and shiny. low, distinctly beaked, T. — Section Liotellina (L.) radiata Linne. 1918. Shell thin, long and with fine concentric sculpture. T. pharaonis Hanley. Fig. the line. Shell fairly strong; surface with distinct, mainly Section Pharaonella (Jousseaume) Lamy, fairly left lateral teeth mantle sinus deep, more or less joined with the mantle Several species, in 920 1887. (part.) P. Fischer, compressed, elongated, posteriorly beaked and 849. Inner side of the right shell valve of Tellina staurella Lamarck. (P.) 1393 Subgenus Scissulina valve; 1924. Dall, hinge as in Macoma. (S.) T. Oblique sculpture only on one dispar Conrad, near the Hawaiian Islands. ADAPEDONTA Suborder Shell without distinct hinge plate, with or without without lateral teeth; teeth, always STIRPS SOLENACEA 1. Shell in main ligament variable. most cases laterally compressed and more or less considerably elongated, gaping at the ends; ligament external, attached on a ridge; hinge margin variable, without only not very deep. mantle sinus in most cases lateral teeth; Mantle closed below, sometimes with a small opening, anteriorly open, posteriorly with 2 short, separate or united siphons; swollen gill laminae smooth or folded; foot strong, more or less long, the end. at 1. Family GLAUCOMYIDAE Shell elongated oval, gaping at the ends, with distinct periostracum; umbo situated anterior to the center, only slightly projecting; short, external or somewhat sunken; hinge margin without mantle sinus deep. Siphons long, retractile, ligament lateral teeth; almost completely united, covered by a membrane; mantle closed below, anteriorly open; foot anteriorly directed; The animals palps broad. labial live in fresh or brackish water. Glaucomya Bronn, 1838 Synonym Glauconome Gray, Shell more or olive-green 1828, non Goldfuss, umbo periostracum; closer to the anterior end; external, projecting, moderately long, attached fairly 1826. elongated, bulging, with strong, in most cases less on one side; narrow, on either side with 3 main teeth, one of which and the posteriormost is obliquely directed; ligament hinge margin is furrowed mantle sinus narrow and deep. Siphons very long, almost completely united, fringed at the end; gill laminae folded; foot G. chinensis (Gray). fairly thick, A tongue-shaped. few species, in east and south Asian rivers. 1394 Tanysiphon Benson, 1855 Shell small and thin, elongated oval, with a brownish periostracum; umbo situated anterior to the center; ligament very short, with an internal borne on very short ridges; hinge margin on the right with cartilage 921 on the left siphonal envelope at the T. 2, with one tooth; mantle sinus large, rounded. At the end of the is a series of tentacles and a series of shorter threads end of the lower siphon. rivalis Benson, in India. The systematic position of these broad sometimes considered close to 1 genera the venerids, is uncertain; they are sometimes close to the solenids. 2. Shell in Family SOLENIDAE most cases elongated; foot large and strong, without byssus; siphons in most cases short; living almost only in the sea. A. Subfamily Novaculininae Shell with strong periostracum, fairly bulging; umbo away from the anterior end, but situated anterior to the center; ligament short; hinge margin on the right with teeth; posterior 2, on the with 3 sometimes rudimentary left adductor muscle scar roundish. The fused ventral surface of the mantle more or less broad, with numerous muscle bands; siphons completely separate; foot short, with disk-shaped end; gill laminae smooth; labial palps broad; intestine with a few long limbs. Novaculina Benson, 1830 Synonym Shell ? Loncosilla fairly Rafinesque, 1820. small and thin, moderately long; umbo somewhat projecting; hinge teeth weak; mantle sinus without connection with the mantle line, anteriorly angulate. Siphons without tentacles; anterior mantle opening smooth; ventral mantle surface very broad. N. gangetica Benson, in the Ganges. 'Correction from Part 4, 1935: 1154. The original German "breiten" was corrected to "beiden," meaning "both.' 1395 Sinonovacula Prashad, 1924 more elongated; umbo scarcely Shell larger and stronger, an impression extending obliquely from ventral margin; mantle sinus short mantle line. it projecting; toward the posterior to the and rounded, joined below with the Siphons with small tentacles; anterior mantle opening with 2—3 rows of short tentacles; ventral mantle surface narrow. constricta (Lamarck), in the sea near China and Japan. S. B. Subfamily Soleninae Shell in most cases very long and laterally umbo more compressed; hinge margin variable; mantle sinus less close to the anterior end; Ventral mantle surface very narrow; foot long and narrow; occasionally smooth, more gill or flat. laminae often folded; intestine with 2 limbs. Siliqua Megerle von Muhlfeld, 1811 Synonyms Leguminaria Schumacher, 1817; Solecurtoides Desmoulins, Machaera Gould, 1841, non Cuvier, 1832. 1832; Shell compressed, moderately long, thin, anteriorly and posteriorly rounded and gaping; umbo not elevated, situated anterior hinge margin on the right with 2, which an accessory ridge extends joined with the mantle line. on the to the ventral margin; mantle sinus Siphons united, with tentacles mantle margin with leafy fringes; foot obliquely truncated laminae smooth; labial palps radiata (Linne). S. A to the center; with 3 main teeth, from left at the end; at the end; gill long and pointed. few species, in various seas. Pharus (Leach) T. Brown, 1844 Synonyms Polia Orbigny, 1843, non Ochsenhausen, 1816; Ceratisolen Forbes & Shell umbo with Hanley, 1848; Artusius Leach, 1852. long, anteriorly rounded, posteriorly somewhat truncated; not projecting, fairly close to the center; hinge margin on the right on the 1 the posterior of which are very oblique, from which an accessory ridge extends anteriorly and a short one 2, 1 right with 3 teeth Apparently an error 3 teeth on the right. — , in the original text, indicating Editors. 2 teeth on the right and also 1396 ventrally; between them lies the muscle; the posterior scar elongated scar of the anterior adductor is triangular, close to the posterior end of the mantle sinus shallow, joined with the lower mantle shell; line. Anterior mantle opening with tentacles only dorsally and ventrally; siphons separated from one another, long and thin; gill laminae smooth; foot long; oral lobes broad. P. legumen (Linne), near Europe and West Africa. Phaxas Leach, 1852 Synonym Shell Subcultellus Ghosh, 1920. similarly formed to that in Pharus, but shorter; umbo and hinge teeth close to the anterior end, in the interior a short anterior accessory ridge anterior to the long scar of the anterior adductor muscle; Posterior part of the mantle opening with posterior scar very small. tentacles; siphons short, separated from one another; laminae folded; gill anteriorly thickened. foot P. pellucidus (Pennant), near Europe. The group of "Solen" cultellus Linne is to be considered as the subgenus Ensiculus H. Adams, 1860, with similar muscle is often speckled, and The siphons margin. Few are somewhat concave is scars; the shell posterior to the umbones. very short and largely united, with tentacles at the species, mainly near the Philippines. Cultellus Schumacher, 1817 Shell not greatly elongated, anteriorly and posteriorly rounded, sometimes large and strong; umbo closer to the anterior end, posterior to the anteriormost quarter; ligament more or somewhat upper margin of the roundish anterior adductor muscle scar thickened; posterior less long; scar pear-shaped; the anterior border of the mantle sinus extends from the center of this muscle scar almost in a straight line mantle line, tentacles; gill laminae folded; labial palps short C. downward to the with which the sinus joins. Siphons short and separate, with lacteus (Spengler). A few and broad; foot strong. species, in the Indo-Pacific region. Coen, 1933, erected a subgenus Cultrensis for C. adriaticus Coen, with straight dorsal margin, small and very thin, on either side with 2 lines from the umbo to the posterior corners. Pharella Gray, 1854 Shell elongated, posteriorly rounded thin, anteriorly and and gaping, with strong, somewhat folded not greatly compressed, 1397 periostracum; umbo situated somewhat posterior to on the the anterior third; with 3 thin and sometimes hinge margin on the right with 2, strikingly high teeth; adductor muscle scars long and narrow; from the left center of the posterior one the boundary of the mantle sinus extends obliquely downward short, with free to the posterior end of the mantle line. ends which bear tentacles; gill Siphons laminae narrow, somewhat folded; labial palps broad; foot long. P. javanica (Lamarck). Few species, on the coasts of the Indo-Pacific regions. Neosolen Ghosh, 1929 Shell small, thin and transparent, about anteriorly truncated, posteriorly VA times longer than high, somewhat rounded, on the right with a long and narrow tooth; anterior muscle scar elongated triangular; posterior one small, roundish. Siphons long, with several rows of tentacles, completely united with one another; gill laminae folded; labial palps weakly compressed, with a ring-shaped thickening. short and broad; foot N. aquaedulcioris Ghosh, in Chilka Lake. Solen Linne, 1758 Synonyms Hypogaea + Hypogaeoderma Poli, 1791, and 1795; Solenarius Dumeril, 1811; Vagina Megerle von MUhlfeld, 1811, Listera Leach, 1852; Fistula (Martini) Morch, 1853. Shell very long, nearly cylindrical, anteriorly truncated, ends; umbo open at both very close to the anterior margin; hinge margin on either side with one tooth; posterior adductor muscle scar and boundary of the mantle sinus far from the posterior margin. Siphons short, completely united with one another, with tentacles on the ends, without ventral mantle opening; gill laminae folded; labial palps long and narrow; foot cylindrical, swollen at the end. A few species, in various seas. Subgenus Solena (Browne) Morch, 1853 (synonym Hypogella Gray, 1854). Shell with strong, folded periostracum, without anterior furrow; umbo and hinge teeth somewhat away from the anterior margin; anterior muscle scar oval. S. (5.) obliquus Spengler. Fig. 850. Shell of Solen siliqua (Linne). 1398 Subgenus Solen umbo and s. s. Surface smooth, often with an anterior furrow; hinge teeth nearly terminal; ligament long. S. (S.) marginatus Pulteney (Fig. 850). Ensis Schumacher, 1817 Synonym Ensatella Swainson, 1840. Shell greatly elongated, weak, curved; long; appressed tooth, on the nearly terminal; ligament left with 2 erect and one posterior ridge-shaped muscle scars greatly elongated; boundary of the mantle tooth; adductor sinus umbo hinge margin on the right with one erect and one posterior not very far from the posterior margin. Siphons short, with tentacles at the margin; mantle with a small ventral opening, separated from the anterior one; gill which is laminae folded; foot long and narrow. magnus Schumacher. Few E. species, in the Atlantic and Pacific Oceans. II. more or Shell irregular, STIRPS SAXICAVACEA less longish, in most cases gaping attached on ridges; main tooth in most cases 924 teeth absent; weak or reduced; lateral mantle line sometimes not continuous; sinus variable. Mantle with small opening for the foot and with largely united siphons gill at the ends, often with concentric striae and a periostracum; ligament external, which in most cases large, are covered completely or by a membrane; laminae smooth or folded, unequally broad, posteriorly fused; foot small. 1. Characters of the Family SAXICAVIDAE stirps. Saxicava Fleuriau de Bellevue, 1802 Synonyms 1808; Didonta Lamarck, Hiatella (Daudin) Bosc, + Glycimeris Schumacher, 1799; Pholeobia Leach, 1802; state Fond, Blainville, 1825. Shell fairly small, longish, often irregularly young S. Da Costa, 1778, nee Rhombus Blainville, 1818; Byssomya Cuvier, 1817; 1819; Agina Turton, 1822; Rhomboides 1825; Biapholius (Leach) Blainville, the Clotho Faujas 1817, non formed and with 2 posterior scale-bearing edges; striated; umbo in situated 1399 on strong ridges; hinge margin which disappear with age; mantle line anterior to the center; ligament attached with 1 or 2 weak main lower one longer; byssus. The sometimes less teeth with more or less deep sinus. Siphons largely united, the interrupted, in laminae smooth; foot gill the in young with preformed caverns of stones; sometimes they bore more or deep into limestone by an acid secreted from glands Few state animals live sometimes on the surface of the substratum, species, in in the mantle. seas. all Subgenus Saxicava s. Shell s. more or fairly thick, irregular, less longish, often gaping; mantle sinus deep. S. (5.) arctica (Linne). Subgenus Saxicavella 1844, non Oken, Fischer, 1887 P. 1815, nee Schumacher, somewhat gaping, oval, posteriorly (synonym Arcinella 1817). Shell umbo angulate; ligament short; mantle sinus broad, not deep. S. Philippi, small and thin, only slightly elevated; (Montagu). (S.) plicata Panomya Gray, 1853 Synonym Chaenopaea C. Mayer, 1885. Shell fairly large and strong, irregular, gaping at both ends, posteriorly truncated, irregularly concentrically striated, with yellowish periostracum; ligament short; hinge margin on either side with one tooth; mantle line fairly far P. from the margin, not continuous. Living spengleri (Valenciennes). Few Panopea Menard de Synonym Glycimeris Lamarck, Shell irregularly la greatly striated; umbo sand or mud. Groye, 1807 1799, non da Costa, sometimes very large and posteriorly truncated, in species, in the Arctic Ocean. thick, bulging, depressed; longish, 1778. in most cases gaping mainly posteriorly, ligament on very strong ridges; hinge margin on either side with a high, cone-shaped tooth; mantle line not interrupted, with more or less deep sinus. Mantle closed except for a small aperture for the foot; siphons very long, completely united and covered by a strong membrane; P. glycymeris (Born). gill Few considerable depth in sand or laminae folded. species, in various seas, living at mud. Cyrtodaria Daudin, 1799 Shell elongated oval, thick, widely gaping, with strong, dark periostracum projecting at the margin; posterior to the center; umbo scarcely projecting, situated ligament on very thick ridges; hinge margin 1400 muscle scar close toothless; posterior adductor below which the mantle to the posterior margin, line is broadened, but scarcely indented. Mantle closed, leaving a small opening at the anterior end; siphons large, not with a thick membrane; retractile, triangular; laminae folded; labial palps large, gill foot weak. siliqua (Spengler), in the Arctic Ocean. C. IE. Shell in most cases STIRPS MYACEA fairly small, not nacreous; cartilage borne asymmetrically below the dorsal margin of the other valve; hinge sinus ligament with internal on a process of one valve, which extends sometimes small or absent, sometimes teeth variable; mantle large. Siphons largely united; mantle closed below, anteriorly with small opening. more or Shell fairly small, ALOIDIDAE Family 1. less asymmetrical, closed in most cases posteriorly angulate or rostrate, often with distinct concentric sculpture; the cartilage bearer of one valve more or is less projecting; the right valve anterior to the cartilage has in most cases a strong tooth, corresponding to which cartilage bearer has a as a pit in the left valve, less distinct tooth; weakly indented. Siphons as a rule not or by a common is more or sheath, which in short, which posterior to the mantle line posteriorly surrounded most cases bears tentacles at the at the does the incurrent siphon; mantle margin with papillae; also base margin, gill laminae smooth; foot with byssus. Aloidis Megerle von Muhlfeld, 1811 ? Synonyms Corbula (Bruguiere) Lamarck, 1799, non Roding, 1798; Harlea + Raleta + Tomala Gray, 1844 (nom. nuda). Shell asymmetrical; left valve with projecting cartilage bearer; mantle sinus absent or weak. Several species, mainly in Subgenus Lentidium warmer Cristofori & seas, a Jan, few in fresh water. 1832 (synonym Corbulomya Nyst, 1846). Shell small and thin, longish, flatly bulging, smooth; right valve only slightly larger than the slightly elevated; cartilage cleft; the of the posterior margin left; umbo close to the center, only somewhat obliquely right valve is visible near the umbo truncated; the through an internal posterior margin of the left cartilage bearer forms a somewhat 1401 convex triangular plate and the anterior margin of the tooth pit forms a the mantle line extends obliquely backward, without triangular tooth; Siphons without ring of tentacles. A. distinct indentation. (Costa), (L.) mediterranea the Mediterranean Sea. in Subgenus Anticorbula 1898 (synonym Himella H. Adams, Dall, Shell thin; left valve larger than the right; right 1 854). 1 860, non Dallas, main tooth rudimentary; external ligament present; cartilage on either side affixed on a nearly horizontal process; mantle sinus weak. A. (A.) fluviatilis (H. Adams), Subgenus Aloidis left, with Amazon in the s. concentric distinct River. Shell inequivalve; right valve larger than the s. sculpture. Section Anisocorbula 1930. Shell compressed, longish, posteriorly with 2 corners; slightly elevated, situated somewhat only slightly larger than the posterior edge; valve left macgillivrayi (Edg. right only valve both with concentric rings and a left, without distinct anterior tooth. A. (A.) Smith), Cuneocorbula Cossmann, anterior to the center; Iredale, umbo in Indo-Australian region. the 1886. Shell — Section elongated oval; the two valves only slightly different, bulging, with an edge to the posterior corner. A. (C.) biangulata (Deshayes) "|\ the living A. contracta (Say) on the North American east coast.—Section Bothrocorbula Gabb, 1872. Shell posteriorly pointed; oval, strong, rings; lunular area also species more or living distinctly inequivalve; fairly short, the in right both valves with strong concentric less depressed. A. (B.) West Indies. — viminea (Guppy) Section Aloidis s. t» Shell valve larger and more strongly sculptured, with more or less distinct posterior beak and an edge, often very thick, with strong, triangular hinge tooth; in the posterior margin of the cartilage bearer sometimes produced tooth-shaped. A. Iredale, s. is (A.) sulcata (Lamarck). 1930, for the Australian N. vicaria Iredale, Varicorbula Grant & left valve the elevated hump-like and is scarcely different; Gale, 1931 [gibba (Olivi)] (Fig. 851) is distinguished only by a weaker edge of the right valve. (\ \ Fig. 851. Inner side of the right shell valve is Notocorbula of Aloidis (Varicorbula) gibba (Olivi). 1402 Subgenus Panamicorbula Pilsbry, 1932. Shell not beaked; right valve only slightly larger, with deeply sunken cartilage bearer, an erect anterior main tooth, and long of which lateral teeth, the posterior is strong; left valve with broad, somewhat erect cartilage bearer and a deep pit anterior A. (P.) inflata (C. B. Adams). Subgenus Erodona (Daudin) Bosc, 1802 (synonyms Potamomya Sowerby, 1839; Azara Orbigny, 1839). Shell longish triangular, weakly to it. sculptured, nearly equi valve; left valve with a strong, obliquely projecting cartilage bearer, the margins of which are elevated ridge-like; right valve with a corresponding indentation of the hinge margin with elevated margins, the pits of which correspond to the other valve. A. (E.) labiata (Maton), in South American rivers. Grippina Dall, 1912 Shell small, triangular, nearly equivalve; right valve with 2 projecting teeth, umbo moderately between which the with furrows corresponding to the dorsal margin of elevated; cartilage rests, left and valve; the latter has no hinge margin; mantle sinus distinctly developed, roundish. G. California Dall, near California. 2. Shell left less large. tentacles; less gaping; attached to a projecting process, which posteriorly fused with the margin and extends right valve; hinge 927 MYIDAE somewhat inequivalve, posteriorly more or ligamental cartilage on the is Family margin without below the margin of the distinct teeth; mantle sinus more or Siphons long, united, with a conchin membrane and a ring of gill laminae folded. ? Paramya Conrad, 1860 Synonym Myalina Conrad, Shell small, 1845, non Koninck, 1842. somewhat quadrangular; umbo situated anterior to the center; both valves with a vertical cartilage bearer without hinge teeth; mantle line posteriorly obliquely descending, without sinus. P. subovata (Conrad), near Florida and South Carolina. Sphenia Turton, 1822 Shell fairly small and thin; umbo closer to the anterior end; right valve only slightly larger than the somewhat pointed left; cartilage bearer 1403 obliquely projecting, with a ridge on a its posterior part; right valve with denticle anterior to the cartilage; mantle sinus moderately weak roundish deep, roundish. Siphons fairly long and thick; foot with byssus. A binghami Turton. S. few species, in various seas. Cryptomya Conrad, 1848 Shell fairly small and thin, oval, nearly equivalve, radial threads; cartilage bearer of the left sometimes with fine valve with elevated anterior margin and posteriorly with a ridge; mantle sinus very shallow. Few species, in various seas. Subgenus Cryptomya s. s. Without cartilage bearer of the left valve. distinct indentation anterior to the C. (C.) California (Conrad). Subgenus Tugonella Jousseaume, 1891 (synonym Venatomya 1930). Left valve Iredale, with an incision anterior to the cartilage bearer, whereby an anterior tooth is separated. C. (T.) tugonella (Jousseaume). Tugonia Gray, 1842 Shell fairly and small thin, greatly bulging, posteriorly greatly shortened and widely gaping, anteriorly rounded and closed, exterioly with radial threads, in inclined; one species only toward the tooth-shaped process, elevated on the posteriorly with a pit umbo in the posterior part; cartilage bearer projecting which corresponds right, posteriorly posteriorly with a left, but obliquely receding, to the tooth of the left valve; mantle line close to the margin, posteriorly not indented. T. anatina (Gmelin). 2 species, near West and East Africa. Mya Linne, 1758 Shell nearly equivalve, oval or posteriorly broadly truncated, gaping at both ends; umbo only slightly elevated; external ligament thin; on the left to a horizontal process, which lies below the margin of the right valve and posteriorly has a slanting ridge, whereas its anterior margin is upwardly curved; the right valve anterior cartilage strong, attached to the cartilage has a weak tubercular thickening; mantle sinus large; siphons very long, with a conchin membrane and at its end with a ring of tentacles; foot small, tongue-shaped, without byssus. Few species, in the northern Section M. (A.) and Arctic Arenomya Winckworth, 1930. arenaria Linne. — Section Mya seas. Shell posteriorly not shortened. s. s. Shell posteriorly broadly truncated and widely gaping. M. (A/.) truncata Linne (Fig. 852). 404 / Fig. 852. Inner side of the shell valve left of / Mya truncata Linne. Platyodon Conrad, 1837 Shell fairly large and strong, elongated oval, bulging, posteriorly truncated and widely gaping, with distinct concentric and sculpture; cartilage bearer horizontal, anteriorly weak radial and posteriorly indented; the right valve has a tuberculate thickening posterior to the cartilage; mantle sinus large. The siphons somewhat P. at the ends have 4 horny, sometimes processes. calcified cancellatus (Conrad), near California. STIRPS IV. Shell more or GASTROCHAENACEA elongated, less anterior part of the lower side; slightly projecting ridge; fairly small, hinge margin toothless; mantle sinus deep. Siphons variably long; mantle closed, leaving opening for the The animals foot. widely gaping in the ligament external, attached to a only a, in most cases small, either live freely in sand and build a club-shaped tube surrounding the shell and siphons or they bore into limestone or molluscan shells. 1. Family Characters of the GASTROCHAENIDAE stirps. Spengleria Tryon, 1862 Shell umbo anteriorly somewhat rounded, posteriorly broadly truncated; not situated very far forward; extending from them toward the 1405 comer ventral posterior a furrow and the part lying above is Siphons fairly separate; short, cylinder-shaped, without anterior gill more anterior muscle laminae folded; foot thick or less distinctly concentrically sculptured; large. is it scar fairly with protractor muscles, ventrally tip, with a byssus gland; the mantle contains no acid-secreting glands. S. mytiloides (Lamarck). Few species, in warm seas, living in sand. Gastrochaena Spengler, 1783 Synonyms Chaena Umbo Retzius, 1788; Rocellaria Blainville, 1828. very close to the pointed anterior end, posteriorly rounded, with uniform concentric sculpture; anterior muscle scar small. Siphons long, united with the into ventral one another; siphon; foot gill laminae smooth, sometimes extending with a more or less large anterior tip, without protractor muscles; the mantle contains an acid-secreting gland. G. cuneiformis Spengler. limestone. into Dufo), is A few species, not substantially different. proposed for animals which bore into less project Fig. 853. in warm seas (Fig. 853), boring Dufoichaena (Jousseaume) Lamy, 1925 (G. dentifera Cucurbitula Gould, shells, 1861, was from which they more or and form an envelope of roundish capsules arranged Gastrochaena ovata Sowerby, seen from the right, in a row. somewhat enlarged. Fistulana Bruguiere, 1792 Shell thin, narrow and elongated; small, angular, ribbed, umbo delimited by an nearly terminal, anterior part edge; posterior part greatly elongated, concentrically striated, widely gaping below; anterior muscle scar small; mantle sinus deep. lies, is club-shaped, closed at The calcareous tube, in which the animal the anterior end, in the interior with a thickening posterior to the shell, exteriorly sometimes with attached sand grains; the posterior part contains the very long united siphons; the mantle has an opening anteriorly for the very small foot; labial small. F. mumia (Spengler). 3 species, in the Indo-Pacific region. palps 1406 V. STIRPS Shell colorless, equivalve, exteriorly in part, ADESMACEA sometimes elongated, sometimes spherical, most cases ribbed and denticulate especially gaping at in the anterior both ends, sometimes anteriorly widely open, without ligament and hinge margin, so that the two valves are joined together only by muscles; anterior part of the dorsal margin broadened and reflected outward; attached to the anterior adductor muscle, which is it does not work together with the posterior one but is however antagonistic to thus it, producing rasping movements of the valves; projecting from the umbones into the interior the of the shell body musculature is a band- or spoon-shaped process, to which attaches; in addition to the shell, the animals produce various accessory calcareous plates or tubes, which sometimes remain unconnected to the shell, less long, largely united; sometimes fuse with it. Siphons more or mantle closed except for an anterior opening for the sometimes rudimentary foot. The animals bore into 1. wood and Family Shell variable in size, in spherical, anteriorly rock. PHOLADIDAE most cases more or less elongated, seldom and posteriorly gaping, sometimes anteriorly wide open; surface with denticulate ribs or rings, which in most cases on the posterior part become weaker or are completely absent; the expansions of the anterior dorsal margins are sometimes nearly parallel, but in most cases outwardly reflected; overlying the dorsal parts are plates produced by the reflected mantle, the anterior of which are known as the protoplax, the median one as the mesoplax, and the posterior one as the metaplax; only the central one has the same structure as the shell. Occasionally there are accessory shell pieces at the posterior end and in a the wide anterior opening is few genera closed by plates which are firmly joined with the shell; mantle sinus more or less deep. Siphons moderately long, without calcareous plates (pallets) scarcely folded, at the ends; gill sometimes the outer one fairly large, triangular; foot short, is laminae rudimentary; in most cases labial palps without byssus, sometimes rudimentary. A. Subfamily Pholadinae 930 Shell anteriorly more or less gaping and not closed in older by a secondary expansion, in most cases without accessory plates posterior end. shells at the 1407 Barnea (Leach) Risso, 1826 Synonym Holopholas Shell elongated; P. Fischer, 1887. umbo situated anterior to the center; surface sculptured throughout the length with tuberculate radial ribs; expansions of the anterior dorsal margin simple or posteriorly without transverse cleft, away from septa; mantle sinus fairly shallow, but the posterior end. Several species, in various seas. Subgenus Barnea Barnea s. s. s. s. Dorsally only a protoplax is present. Section Shell anteriorly rounded and only slightly gaping. B. (B.) Candida (Linne). — Section Anchomasa Leach, 1852. Shell anteriorly pointed and widely gaping. B. (A.) parva (Pennant). Subgenus Cyrtopleura Tryon, 1862. Shell anteriorly rounded, gaping below, the dorsal expansions demarcating a cross-shaped area, which is covered by a horny lamella. B. (C.) crucigera (Sowerby). & Subgenus Scobinopholas Grant Bayle, 1880, non Lepeletier, 1825). Gale, Shell 1931 large (synonym Scobina and strong, strongly sculptured, anteriorly rounded, with a triangular protoplax and a small mesoplax. B. (S.) costata (Linne). Zirfaea (Leach) Gray, 1842 Synonym Shell Thurlosia (Leach) Scudder, fairly small, anteriorly 1882. pointed and very widely gaping, posteriorly truncated, a groove descending from the umbo dividing each valve into an anterior part sculptured with pointed teeth and a posterior part with smooth rings; the dorsal expansion is reflected and is largely appressed, simple; 2 triangular accessory plates are rudimentary; mantle sinus large. Fig. 854. Inner side of the right shell valve of Zirphaea crispata (Linne). a, the outwardly reflected part. 1408 Z. crispata (Linne) (Fig. 854). Few species, in various seas. Pholas Linne, 1758 Shell elongated; posterior part reflected dorsal more weakly or not denticulate; the margin consisting of 2 lamellae, one of which appressed, whereas the other free; is is largely the two are connected with one another by a few transverse septa, in most cases the protoplax, mesoplax, and metaplax are developed; mantle sinus Few large, rounded. species, in various seas. Subgenus Monothyra Tryon, 1862. Shell anteriorly rounded and only slightly gaping; posterior part smooth; dorsally a protoplax and a very narrow metaplax are present. P. 931 (M) orientalis Gmelin. Subgenus Thovana Gray, 1847 (synonym Gitocentrum Tryon, 1862). Shell anteriorly rounded and only slightly gaping; protoplax paired, with nuclei on the inner and narrow. P. (T.) campechiensis Gmelin. Subgenus Pholas anteriorly pointed mesoplax small and transverse; metaplax long side; s. s. (synonym Dactylina Gray, 1847). Shell and widely gaping; protoplax paired, with nuclei on the outer side posterior to the center; mesoplax and metaplax present. P. (P.) dactylus Linne. Talona Gray, 1842 Shell thin and moderately long, bulging, a major part sculptured with tuberculate concentric rings; the elevated dorsal margins are simple, parallel to present, one another, not appressed; 2 symmetrical accessory plates are which overlie the umbones, and a few half calcified ones at the posterior ends; mantle sinus moderately deep, tongue-shaped. T. explanata (Spengler), near West Africa. Xylophaga Turton, 1822 Synonyms Dall, ? Xylotrya (Leach) Menke, 1830, nom. nud.; Xylotomea 1898. Shell fairly small, spherical, similar to Teredo with a large angular anterior indentation, posteriorly only slightly gaping; the anterior part is sculptured with finely denticulate ridges parallel to the margins; the posterior part, separated umbones, is by a flat furrow descending from the elevated sculptured with very dense, smooth, concentric striae; below the outer furrow extends an internal rib which projects wart-like at the end; the anterior dorsal margin is outwardly curved and bears 2 small 1409 obtusely angled plates; inner process small. Siphons fairly thin, united nearly to the end; their retractor below short; is their attachments extends a fairly strong muscle from one valve to the other; the posterior adductor muscle large, is the anterior one very weak; open; foot disk-shaped, short; outer X. dorsalis (Turton). various seas. Because the mantle anteriorly widely lamina absent. Few species, some of which are name Xylophagus was proposed name Xylotomea suggested the gill doubtful, in earlier, Dall for Xylophaga. B. Subfamily Martesiinae Shell in the young widely open, state anteriorly dorsally send out a more or less wavy or denticulate concentric separated by a descending furrow from the posterior part, is which often bears horny or calcareous plates Nettastomella Carpenter, Rafinesque, at the end. 1865 (= Nettastoma Conrad, 1810) and Navea Gray, which probably belong shells, by an broadened, in most cases appressed process; the anterior part, sculptured with threads, later closed expansion, the margins of which are firmly joined and sculptureless 1864, non 1851, were proposed for juvenile to this subfamily. Pholadidea (Goodall) Turton, 1819 Synonym Cadmusia Leach, Shell longish, 1852. anteriorly bulging; upper part with wave-shaped concentric threads, lower part indistinctly sculptured; posterior half only slightly bulging, grown and concentrically of variable shells size, striated; single or paired; protoplax only in fully mesoplax and metaplax rudimentary; at the posterior end each valve has a horny process and may be fused with the opposite form a tube. Siphons completely united and with a fringed disk sometimes a calcareous groove, which one at to the end; mantle nearly completely closed. Foot with age; gill becoming rudimentary laminae not folded, very unequal; labial palps long and narrow. A few species, in various seas. Section Pholadidea s. s. Shell with a radial furrow; protoplax paired, very small; posterior processes cup-shaped, not folded, without calcareous tube. P. (P.) loscombiana Goodall. posteriorly with which shows a — Section Talonella Gray, 1851. Shell 2 curved swellings and processes, the inner side of tripartite callus. P. (T.) tridens (Gray). — Section Hatasia Gray, 1851. Shell posteriorly with 2 horny processes and a calcareous tube. P. (H.) melanura (Sowerby). — Section Penitella Valenciennes, 1410 1846. Shell posteriorly with 2 diverging horny plates, anteriorly with a broad appressed reflection; protoplax formed of 2 plates largely joined with one another; mesoplax small, triangular P. (P.) penita (Conrad). — Section Calyptopholas Lamy, 1928. Shell fairly with a very short, large protoplax enveloping the anterior part; at the posterior end with a calcareous, rounded process of each valve and around the siphons with a calcareous tube which lines the wall of the cavity produced animal in by the Lamy, near Annam. a coral (Pontes). P. (C.) cheveyi Parapholas Conrad, 1848 Shell on longish, either side furrows, the anterior section is divided into 3 sections by 2 radial sculptured above with wavy lamellae, below with weak striae, whereas the middle one bears a thick periostracum, the posterior one horny lamellae; the paired protoplax sometimes attains considerable size, posterior to it lies a long paired metaplax, occasionally there also a ventral, paired, narrow hypoplax; whereas the posterior end lacks processes joined with the shell, the surrounding cavity is lined by a calcareous tube; posterior adductor muscle scar elongated; mantle sinus very flat, P. but away from the posterior end. californica (Conrad). A few species, in warm seas. Martesia (Leach) Blainville, 1825 Shell in on either most cases fairly small and dorsally with a paired, side; thin, with a descending furrow more or less large protoplax, a narrow metaplax, and seldom a mesoplax; ventrally with a narrow paired hypoplax; sometimes the valves are posteriorly elongated into thin calcareous lamellae. Siphon as in Pholadidea; their retractors are divided into 2 bundles A on either few species, in side. warm seas; one, M. rivicola (Sowerby), in rivers near the mouth. Section Martesia s. s. (synonym Martesiella Verrill & Bush, 1898). Protoplax moderately large; a mesoplax absent. M. (M.) striata (Linne). — Section Diplothyra Tryon, 1863. — A mesoplax present. M. (D.) caribaea Section Aspidopholas P. Fischer, 1887 (synonym Scutigera Cossmann, 1886, non Lamarck, 1801). Protoplax very large; a calcareous tube lining the surrounding cavity. M. (A.) scutata (Deshayes) f; the living M. yoshimurai (Kuroda & Teremachi), near Japan. (Orbigny). For Pholas semicostata H. C. Lea, the shell of which produced as a 933 short, is posteriorly cone-shaped tube, Dall, 1898, proposed a genus Scyphomya, whereas Tryon and Lynge considered the species identical 1411 with Martesia striata; the dorsal plates are said to be similar to those in Pholadidea. Jouannetia Des Moulins, 1828 by a furrow Shell nearly spherical, inequivalve; right valve divided into a large anterior and a small posterior one part sculptured with more or less wavy former consisting of part, the concentric threads and in the adult animal a broad, dorsal posteriorly reflected and appressed, indistinctly sculptured part; adjoining the posterior margin of the narrow posterior part is the larger left valve has no tongue- a tongue-shaped process; shaped process posteriorly; the posterior part second radial furrow; the dorsal reflection covers a part of the right valve. The mantle is by a further divided greatly is expanded and also anteriorly closed, leaving is a small opening; foot reduced in the adult animal; gill laminae distinctly folded. Few species, in warm Subgenus Jouannetia seas. s. s. Posterior processes of the right valve smooth margined; a lamella extending between the short and the posterior dorsal part in posterior adductor muscle. J. (J.) semicaudata J. internal process both valves, attached to which Des Moulins is the t; the living cumingi Sowerby. Subgenus Triomphalia Sowerby, 1 849 (synonym Pholadopsis Conrad, 1849). Posterior process of the right valve with cuspidate margin; in the interior without lamellae for the posterior adductor muscles. globulosa (Quoy & J. (T.) Gaimard). 2. Family TEREDINIDAE Shell very small in comparison with the animal and covering only its anteriormost part, equivalve, without accessory pieces; it consists of a strongly curved triangular part and an anterior and posterior piece; the anterior plate is triangular, separated from the central part by a large angulate indentation and externally sculptured with finely denticulate concentric ridges; the central part shows 3 fields, the anterior of which is beset with denticulate ridges, whereas the centralmost somewhat deepened, and the posteriormost piece the posteriormost field is is is narrow and concentrically striated; ear-shaped, on the inner side in most cases delimited by a strong infolding; it serves for attachment of the strong posterior adductor muscle, where as the weak anterior adductor muscle attaches to a reflection of the anterior dorsal margin; the inner side a narrow free process and a median rib ending in a knob. shows The animal is 1412 greatly elongated, with partially united siphons, which are characterized by the presence of a pair of peculiar, in most cases spoon- or feather-shaped calcareous structures (pallets); the visceral sac, which is otherwise situated ventral to the adductor muscles, is here posteriorly turned and elongated, so that the stomach and intestine are the most ventral; pericardium and kidney are situated above them and posterior to the posterior adductor muscle; the ventricle is is not traversed by the intestine; the outer lamina gill rudimentary, the inner one very long and narrow; the foot weak; oval lobes very narrow. The animals 934 wood in known are as ship worms, boring into the destroying marine construction and embankments; the cavities produced by them through rasping movements of the valves are lined with shell calcareous tubes. Teredo Linne, 1758 Synonym Xylophagus Meuschen, Pallets stalked, simple, not 1781. plumose, rounded at the end, truncate or forked (Fig. 855a). fig. 855. Inner side of the left shell a, pallet valve of Teredo petersi Roch. Height 1 cm. of the same species. Several species, in various seas. Subgenus Teredo s. s. Shell valves about as long as high (Fig. 855). Section Psiloteredo Bartsch, 1922. shell The posterior ear-shaped piece-of the not separated from the central part by infolding; pallets spoon- shaped, with a Stimpson. — weak depression at the end of outer Section Zopoteredo Bartsch, the shell separated from the central part only side. T. (P.) dilatata The 1923. by a posterior piece of distinct line; distal part of the pallets very short and broad, distally with a horny part infolded the center. T. (Z.) clappi Bartsch. — Section Teredora Bartsch, in 192L (synonym Malleolus Gray, 1847, non Rafinesque, 1815, nee Ehrenberg, — 1413 by an 1838). Posterior shell piece separated from the central part as also in all which proximally and malleolus Turton. — laterally surrounds a fingernail-shaped part. T. (T.) Section Nototeredo Bartsch, 1923. Shell as in Teredora; similar to those in Psiloteredo. pallets infolding, following groups; pallets exteriorly with an elevated margin, T. edax Hedley. (TV.) — Section Neoteredo Bartsch, 1920. Pallets spoon-shaped, depressed cup-like end. T. {N.) reynei Bartsch. — at the Section Teredops Bartsch, 1921. Pallets leaf- shaped, with a calcareous knob at the end. T. (T.) diegensis Bartsch. Section Coeloteredo Bartsch, 1923. Pallets with a thin, exteriorly bulging, interiorly nearly flat, distally Bartsch. — somewhat concave lamina. Section Spathoteredo Moll, broad, nearly quadratic lamina. Gould, Gould. 1928. T. (S.) batilliformis Section Teredo (T.) navalis Linne. s. s. — with a double cup Pallets mindanensis with long-stalked, Clapp. 1870. Pallets leaf-shaped forked at the end. — T. (C.) Pallets — T. Section Lyrodus chlorotica (I.) deepened bowl-shaped at the end. T. Section Teredothyra Bartsch, 1921. Pallets fairly long, at the end. T. (T.) Ungoteredo Bartsch, 1927. Pallets with a dominicensis Bartsch. fairly short plate, has 2 deep, cup-shaped depressions separated by a slit. T. — which Section at the end (U.) matocotana Bartsch. Subgenus Hyperotus Guettard, 1770 (Uperotus) (synonym Guetera Gray, 1 847). Shell considerably higher than long, with small anterior and posterior parts, the posterior one freely projecting; long, exteriorly concave lamina, irregular, radiating, which is somewhat prominent Gmelin. The animals bore into floating pallets with fairly sculptured in the distal half with ridges at the end. T. fruits (//.) clava of Carapa moluccensis; their calcareous tubes are strongly coiled and fairly short and strong. Eoteredo Bartsch, 1923, is said to be characterized by the internal process arising not from the umbones but from the infolding separating the posterior ear-shaped part from the median part of the shell, but this is evidently only due to strong erosion of the umbonal area and may also happen otherwise; the pallets are unknown. E. philippinensis Bartsch. A genus Kuphus Guettard, 1770 (= Cyphus P. Fischer, 1887; synonyms Furcella Lamarck, 1801; Septaria Lamarck, 1818, non Ferussac, 1807; Clossonnaria Ferussac, 1822; Clausaria Menke, 1828) was proposed for T. arenaria (Linne); the tubes attain considerable size, and are cleft at the posterior end or separated by a partition; they do not live in wood but free in sand, for which reason Lamy places them in subfamily Kuphinae; the shells are not sufficiently known; the pallets are long stalked with a triangular plate, the distal cavity of which into two halves by a median rib. is divided 1414 Bactronophorus Tapparone Canefri, 1877 Synonym Calobates Gould, 1862, non Kaup, 1829, nee Temminck, 1839. Anteriormost part of the shell very large in comparison with the posterior ear-shaped part; rooted in the triangular plate, distally somewhat B. distal broadened lamella, cavity of which which is is a band-like, nearly as long as the stalk siphons nearly completely united. 856a); (Fig. long stalked, with a short, broad, pallets thoracites (Gould), near eastern Asia. 1 i tl u Fig. 856a. Pallet of Bactronophorus thoracites (Gould). Zachsia Bulatoff Shell very weak, is its & Rjabtschikoff, 1933 anterior part forming no projecting angle, but convex, somewhat incurved at the margin, with a few ribs which bear is very small and Only the small anterior unequal oblique teeth; the posterior ear-shaped part weak; the internal process of the part thin, needle-shaped. shell is free, the posterior broad and simple as in Teredo. The covered by a mantle fold. Pallets larvae develop into elongated forms within the maternal mantle cavity. Z. zenkewitschi Bulatoff & Rjabtschikoff. 2 species in the roots of Phylospadix ruprechti, near eastern Asia (Vladivostok). Bankia Gray, 1842 Shell similar to that in Teredo; pallets more or less long, several small funnel-shaped calcareous structures fitting into (Fig. 856b). formed of one another — 1415 Fig. 856b. Pallet of Bankia (Bankiella) gouldi Bartsch (after Bartsch). A few species, in various seas. Subgenus Nausitora Wright, 1864. The funnel-shaped parts are more or less densely placed, united on the external surface and covered by a calcareous layer. B. (N.) dunlopi (Wright). Subgenus Bankia s. s. The funnel-shaped parts are covered by a thin membrane. Section Bankiella Bartsch, membrane is smooth at the free margin. B. Section Neobankia Bartsch, — Section Bankia free, 1921. This mexicana Bartsch. 1921. Free margin of the denticulate. B. (N.) zeteki Bartsch. membrane (/?.) distally s. s. membrane finely Free margin of the fringed; the lateral tips have long processes. B. (B.) bipalmulata (Lamarck). Suborder Shell often most cases with thin, ANOMALODESMATA inequivalve and internally nacreous; ligament in which often contains a calcareous structure (lithodesma); hinge teeth weak or absent; mantle sinus and siphons more or less developed; gonads as a rule hermaphroditic (Fig. 857). internal cartilage, 1416 Fig. 857. a, Pandora elongata Carpenter. anus; aa, ap, anterior and posterior adductor muscle; p, labial palps; pe, pericardium; 1. Inner gill STIRPS t, testis; v, f, foot; k, gill; o, ovary; ventricle (after Pelseneer). PANDORACEA lamina well developed, folded, the outer one more or less reduced, in most cases forming a narrow, upwardly-directed lamella. Without calcareous tube outside the 1. Family shell. LYONSIIDAE most cases thin and somewhat inequivalve, Shell in exteriorly with more or interiorly nacreous, less strong periostracum, longish; toothless; the internal ligament is attached in a hinge margin narrow groove near the margin and contains a lithodesma; mantle sinus shallow; siphons short and separate, without separate retractors; foot with byssus; outer gill lamina fairly broad. Lyonsia Turton, 1822 Synonyms Magdala (Leach) T. Brown, 1 827; Hiatella T. Brown, 1 827, non Daudin, 1802; Tetragonostea Deshayes, 1830; Myatella T. Brown, 1832; Osteodesma Deshayes, 1835, non Blainville, 1825; Pandorina Scacchi, 1836, non Bory de St. Vincent, 1824. Characters of the family. A few species, in various seas. Subgenus Lyonsia Lyonsia 937 s. s. s. s. Shell thin; umbo close to the center. Section Surface with fine radial threads and often with attached sand grains. L. (L.) norvegica (Chemnitz). — Section Allogramma Dall, 1903. — 1417 Shell with radial and sometimes slanting, occasionally somewhat spiny folds. L. (A.) formosa Jeffreys. Subgenus Entodesma Dall, 1845. Shell more or or in sponges, or colonial ascidians. holes, in live Philippi, less irregular; close to the anterior end, with strong periostracum; the animals umbo Section Philippina 1901. Shell fairly small, thin, anteriorly short and ventrally gaping, posteriorly compressed. ascidians. — (P.) L. Section Entodesma ligament long, with s. beana Orbigny. Living s. lithodesma. L. large sponges or in Shell fairly large and strong, inflated; (E.) chilensis (Philippi). Section Agriodesma Dall, 1909. Shell large and thick, with very strong periostracum, ventrally broadly gaping; lithodesma very large. L. (A.) saxicola Baird. Living in cavities of stones. Mytilimeria Conrad, 1837 most cases Shell equivalve, thin, in more or irregularly oval, bulging, with a smooth periostracum, interiorly nacreous; umbo less close to the anterior end; ligament fairly long, on either side attached in a furrow close to the margin, with a lithodesma; muscle scars small; mantle sinus shallow. Mantle margins thick; siphons with wide opening; foot and labial palps very small. M. nuttalli The genus Few Conrad. is species, in the Pacific and Atlantic Oceans. sometimes placed beside Lyonsiella, sometimes beside Lyons ia. 2. Shell Family PANDOR1DAE compressed, longish, posteriorly beaked; dorsal margin often concave posterior to the umbones; outer layer consisting of small, irregular prisms; inner side nacreous; right one flat; left valve as a rule bulging, the more or less umbones and umbones on the inner ligament with a narrow cartilage, which is obliquely posteriorly directed from the scarcely projecting is affixed in furrows; accessory ridges run from the side of the shell; mantle line discontinuous, without indentation. Siphons very short; mantle with an anterior opening for the fairly large foot, which has a small byssus groove; outer gill lamina very narrow. Pandora (Hwass) Chemnitz, 1795 Synonyms Calopodium (Bolten) Roding, 1798; Trutina 1827; Pandorella Conrad, 1863. Characters of the family. T. Brown, 1418 A few species, in various seas. Section Pandora 2 internal ridges; inaequivalis (Linne). s. s. left Cartilage without lithodesma; right valve with weak valve with a — ridge or without same. P. (P.) Section Kennerleya Carpenter, 1864 {Kennerlia). Cartilage with lithodesma; internal ridges similar to those in s.; s. — valve with a few radial right lines. P. (K.) filosa Pandora (Carpenter). Section Frenamya Iredale, 1830 (synonym Coleodon Carpenter, 1865, non Audinet-Serville, 1832, nee Lund, 1838). Cartilage without lithodesma; right valve with 3 ridges; left valve with a posterior and an angle-shaped anterior ridge. P. (F.) patula (Tate). — Section Clidiophora Carpenter, 1864. Cartilage with lithodesma; right valve with 3 ridges, the posterior 938 of which is very long, the anteriormost in low; anterior to the cartilage, the anterior of muscle — scar, left valve with 2 ridges which ends behind the adductor and a long posterior one. P. (C.) claviculata (Carpenter). Section Heteroclidus Dall, ridges, the left posterior 1903. Cartilage with lithodesma; one absent arid the right posterior both anterior ridges end anterior to the anterior muscle one of the is short; scar. P. (//.) punctata Conrad. 3. Family M YOCHAMIDAE Shell inequivalve; dorsal margin of the that more bulging valve enclosing of the opposite valve; hinge margin toothless; ligament with 2 lithodesma; mantle sinus small. Mantle with an opening for the foot and a small one anterior to the lower siphon; siphons moderately long, separate; foot small or rudimentary; labial palps large, triangular. Myodora Gray, 1840 umbo Shell not cemented, compressed, fairly thin; projecting, sometimes closer to the posteriorly truncated, center, exteriorly with concentric rings shaped prisms, parallel to the margin, arranged valve bulging, the left one flat; angulate, scarcely sometimes to the anterior end, in and with rodlet- regular rows; right dorsal margin of the right valve with a furrow corresponding to the margin of the left valve; ligament triangular, below the umbones, with sickle-shaped lithodesma; inner side shiny nacreous; anterior adductor muscle scar narrow, the posterior one situated roundish. M. brevis (Sowerby). Oceans. A few species, in the Pacific and Indian 1419 Myochama Stutchbury, 1830 Shell highly inequivalve; right valve left flat, cemented onto other bivalves; valve greatly bulging, irregularly ribbed; cartilage affixed in a pit on either side, with a lithodesma; the dorsal margins beside the cartilage may be thickened somewhat tooth-shaped; anterior adductor muscle scar longish, the posterior one roundish; mantle sinus angular. M. anomioides Stutchbury. Few Australian 4. species. CHAMOSTREIDAE Family Shell highly inequivalve; right valve greatly deepened and by the anterior half; valve left with rough growth lines; side affixed in a pit, umbo ligament; the but the tooth and pit pit, large, the anterior anteriorly inrolled; to one very long, line without indentation. cemented inner side nacreous-like; outer side ligament on either with large, curved lithodesma; cone-shaped tooth anterior corresponding flat; may be left right valve with a valve with a absent; muscle scars parallel to the anterior margin; mantle Siphons very short; mantle completely closed or with a small opening for the foot and one on the ventral side; foot very small; gill laminae strongly folded; oral lobes narrow. Chamostrea (Roissy) Synonym Cleidothaerus Blainville, Stutchbury, 1825 1829. Characters of the family. C. albida Lamarck. 2 Australian species. 939 5. Family Shell very thin, equivalve, PHOLADOMYIDAE more or less distinctly radially sculptured; ligament external, affixed on ridges; a weak cartilage below the umbones is often borne on a and indentation weak tooth-shaped tubercle of one valve; mantle line most cases long, completely between the anterior mantle opening and the siphons a very small opening is present; foot small; gills thick and finely folded. indistinct. Siphons in united; Parilimya Melvill & Standen, 1899 Shell oval, thin, posteriorly only slightly longer than anteriorly, with indistinct radial folds; on the left with a weak tooth and on the right with a triangular pit below the umbones. 1420 P. haddoni (Melvill & Standen), in the Torres Strait, in shallow water. Pholadomya G.B. Sowerby, 1823 Shell more or less longish; umbones close to the anterior end, fairly inflated, with tuberculate radial folds; posterior margin of the attachment of the cartilage P. Candida Sowerby. Few species, end gaping; the anterior may be somewhat in the Atlantic elevated. and Pacific Oceans, in deep water. Panacea Synonyms Aporema 1905 Dall, Dall, 1903, non Scudder, 1890; Notomya Cotton, 1931. Shell triangular, inflated, anteriorly very short, posteriorly rounded, somewhat depressed below the umbones; surface with a few threadshaped radial folds; external ligament borne on fairly strong ridges; inner side very shiny. P. arata (Verrill) (Fig. 858). one near Tasmania, Fig. in Few most cases 858. Shell of 6. species, in the Atlantic Ocean, in the Panacea arata Family deep and sea. (Verrill) (after Verrill). THRACIIDAE Shell thin, not nacreous, composed of small, irregular prisms, somewhat inequivalve, without hinge teeth; internal ligament in most cases only slightly sunken; mantle sinus moderately deep. Siphons long, separate; mantle on the ventral side with a small opening; foot small, without byssus; labial palps broadly triangular. 1421 Thracia (Leach) Blainville, 1824 Synonym Odoncinetus O. G. Costa 1 829 = Cinetodonta Herrmannsen, 1847. more or less longish, anteriorly rounded, posteriorly broadly in most cases anteriorly and posteriorly somewhat gaping; Shell truncated, umbo close to the center; surface concentrically striated or with irregular granulations; external ligament short, internal one borne on an oblique expansion of the dorsal margin which slightly projecting, is downwardly in most cases only with an occasionally weak and fragile lithodesma; mantle sinus broad and more or less deep. Several species, in various seas. 940 Subgenus Cyathodonta Conrad, 1849. Shell with concentric hinge line not interrupted; umbo folds; not perforated; cartilage bearer short, rounded, projecting below; lithodesma thin, semicircle-shaped, vertically T attached anterior to the cartilage. Subgenus Thracia umbo s. (C.) undulata (Conrad). Shell concentrically striated and granulose; most cases perforated due in cartilage bearer Section s. more or Thracia s. s. less elongated Lithodesma to rubbing against one another; and ventrally only short, transverse, slightly projecting. a furrow lying in anterior to the cartilage; mantle margin not elongated posteriorly. T. (T.) — pubescens (Pulteney). Section Homoeodesma P. Fischer, 1887. Lithodesma more or less rudimentary; mantle margin elongated posteriorly and enclosing the base of the two siphons. Subgenus Phragmorisma Tate, 1 folds; right valve flatly bulging, the left the center; T. (//.) conradi Couthouy. 894. Shell fairly large, with concentric one nearly flat; umbo on strong processes below the umbones. cartilage close to T. (P.) watsoni E. Smith. Subgenus Ixartia Leach, 1852 (synonyms Rupicola Fleuriau de 1802, non Brisson, 1760; ? Pelopia H. Adams, 1868). Shell irregular; cartilage bearer short, roundish, projecting freely downward, Bellevue, with lithodesma. T. (/.) ? distorta (Montagu). Tyleria H. Shell thin, oval, posteriorly which fairly T. is A. Adams, 1854 somewhat truncated and gaping, rounded; ligament partly external; directed, extending anteriorly & pit from anteriorly of the cartilage obliquely posteriorly it parallel to the margin is a ridge joined to the margin by a few transverse plates; mantle sinus small. Animal unknown. fragilis Spondylus shell. H. & A. Adams, near Mazatlan. Found in hole of a 1422 Asthenothaerus Carpenter, 1865 Shell somewhat inequivalve, oval or rounded triangular, anteriorly longer than posteriorly; hinge margin without teeth or processes; cartilage with large lithodesma; mantle sinus deep. Few American species. Subgenus Asthenothaerus s. Shell s. finely granulose, posteriorly somewhat gaping; external ligament rudimentary; lithodesma X-shaped, lying below the posterior part of umbones. A. (A.) villosior Carpenter. Subgenus Bushia Dall, 1886. Shell not granulose, not gaping; ligament external; umbo interiorly thickened; lithodesma very large, transversely arch-shaped A. (B.) elegans Dall. ? Shell small, Parvithracia Finlay, 1927 finely concentrically striated, triangular, margin very narrow; right valve with and a triangular tooth anterior to white; hinge an anterior long and narrow lamella the umbo; left valve with a broad elevated tooth; cartilage fairly long and narrow; mantle sinus deep. P. suteri Finlay = Montacuta triquetra Suter (non Verrill & Bush), near Stewart Island. Thraciopsis Tate Synonym & May, 1900 1867, non Johnson, 1861. Alicia Angas, Shell longish, exteriorly microscopically granulose, anteriorly rounded, posteriorly short truncated; 941 hinge margin on the right with a callous thickening corresponding to a depression on the cartilage left, and a marginal ridge; below the umbones, with a triangular lithodesma; mantle sinus deep. T. angustata (Angas). Iredale, A few Australian species. 1924, proposed a genus Eximiothracia for "Alicia" speciosa Angas, with the statement that 7. Family it has an external ligament. LATERNULIDAE most cases exteriorly granulose and interiorly shiny cartilage borne on processes, from which an accessory ridge extends obliquely backward; umbo cleft; Shell oval, in nacreous; hinge margin toothless; mantle sinus distinct. 1423 A. Subfamily Periplomatinae Shell more or less inequivalve; mantle sinus moderately deep; siphons naked; mantle with a small anterior opening for the foot and one below the ventral siphon. Periploma Schumacher, 1817 Shell distinctly inequivalve, exteriorly granulose, interiorly shiny nacreous; right valve deeper and largely enlosing the end short, truncated, on processes, which directed; between somewhat left; and somewhat gaping; ligament completely distinctly project into the interior their upper margin and the shell posterior internal, and are anteriorly margin a half-moon- lies shaped lithodesma and from their base runs a ridge-like thickening along the posterior margin of the shell to the adductor muscle scar; the mantle line runs close to the P. inaequivalve margin and forms a triangular indentation posteriorly. Schumacher = margaritaceum (Lamarck). Few mainly North American species. Dall, 1904, proposed a section Halistrepta for P. sulcatum Dall, characterized by irregular wavy concentric folds similar to those in Cyathodonta. Iredale, 1930, erected a genus which only a right valve Pendaloma for P. micans Hedley, for from Sydney has been described; the shell is very thin, short beaked, finely granulose and with a few concentric folds; umbo cleft; downwardly inner side somewhat shiny silver; cartilage bearer small, directed. Cochlodesma Couthouy, 1839 Shell compressed, than anteriorly; somewhat inequivalve, posteriorly slightly shorter bearer downwardly directed; mantle sinus cartilage anteriorly rounded. Few species, in the northern Atlantic Ocean. Subgenus Cochlodesma Shell exteriorally not granulose; cartilage s. s. bearer posteriorly with a callous thickening and a ridge running to the adductor muscle scar; without lithodesma. C. (C.) leanum (Conrad). Subgenus Bontaea (Leach) T. Brown, 1844 (synonyms Ligula Montagu, 1808, non Bloch, 1782, nee Mus. Calonn., 1797; Galaxura Leach, 1 852; Calcaraea Recluz, 868). Shell exteriorly granulose; cartilage 1 bearer without callous thickening, with a small sickel-shaped lithodesma. C. (B.) praetenue (Pulteney). 1424 Offadesma Iredale, 1930 Shell thin, fairly large; right valve inflated, the left one flatly bulging; umbo 942 situated somewhat posterior to the center; posterior end gaping; outer side finely granulose; cartilage bearer downwardly directed, with posterior accessory ridge; mantle sinus triangular. Siphons naked. O. and angasi (Crosse New & P. Fischer), near South Australia, Tasmania, Zealand. B. Subfamily Laternulinae Shell longish, thin, nearly or completely equivalve, ventricose, posteriorly gaping, exteriorly rough, internally shiny nacreous; cartilage bearer downwardly projecting, supported by a descending lamella and a thickening near the margin; mantle sinus large. Siphons moderately long, united, with present, horny epidermis, at the some of which may contain for the foot; labial palps long end of which a ring of tentacles is eyes; mantle with a small opening and pointed; the inner gill laminae are united with one another posterior to the foot. Laternula (Bolten) Roding, 1798 Synonyms Auriscalpium Megerle von Muhlfeld, 1811; Anatina 1816; Butor Gistel, 1848, non Forster 1827, nee (Lamarck) Bosc, Swainson, 1834; Butorella Strand, 1928. Characters of the subfamily. L. anatina (Linne). Several species (Fig. 859), in various seas. \ Fig. 859. Shell of Laternula anatina (Linne), seen from the left. 1425 STIRPS II. The CLAVAGELLACEA interiorly nacreous shell both valves are embedded remains more or less small and one or in a calcareous tube, which is sometimes simple, sometimes at the anterior end perforated sieve-like and carrying a of fine tubules. The number mantle has a very small opening for the foot and long, united siphons; foot small, without byssus; gills long and narrow, strongly folded; outer lamina simple, upwardly directed. Family CLAVAGELLIDAE Characters of the stirps. Clavagella Lamarck, 1818 Shell inequivalve, irregular, flattened, finely granulose; left valve fused with the inner side of the tube; right valve weak rests free; the hinge margin has a projection and an indistinct depression posterior to on a small ridge; sometimes divided by limestone, mantle sinus deep. posterior end simple or with opening for the the ligament less long, a longitudinal ridge; anterior end either bored into or molluscan corals, it; Tube more or shells, wavy folds. or free with a small opening; Mantle closed except for a small of tentacles and the lower one foot; siphons with a ring fringed at the end; foot small, finger-shaped, with a short groove; oral lobes triangular; gills posteriorly united and projecting into the ventral siphon. Few species, in various seas. Section Dacosta Gray, 1858. Both ends of the tube simple. C. (D.) 943 australis Sowerby. posterior end Stoliczka, — Section Bryopa Gray, folded. C. (B.) aperta 1842. Anterior end simple; Sowerby. —Section Stirpulina 1870. Anterior end with a median cleft and surrounded by branched tubules; posterior end with lamellae. C. — Section Clavagella C. (C.) echinata s. s. Lamarck (S.) ramosa Dunker. Anterior end with irregular spiny processes. f. Brechites Guettard, 1770 Synonyms Bunodus Guettard, 1770; Penicillus Bruguiere, 1792; Verpa (Bolten) Roding, 1798; Aquaria Perry, 1811; Arytene Oken, 1815; Aspergillum Lamarck, 1818. Shell very small, nearly equivalve, with fine radial striae, completely fused with the outer side of the tube. The like, and often surrounded by a frill latter is long, perforated sieve- of longer, often bifurcated tubules, 1426 wavy margins. Mantle with posteriorly sometimes with broad a small anterior opening for the foot and a small ventral opening; siphons very long; foot very small; gills adductor muscles posteriorly united; rudimentary. A few species, in warm seas. Subgenus Humphreyia Gray, 1858. Tube attached, quadrangular anteriorly with irregular tubules. B. (//.) Foegia Gray, 1842. Anterior end without (F) novaezelandiae (Gray). — strangei (Gray). frill; Section Brechites Schumacher, 1817). Anterior end with a frill end simple. B. (Fig. javanus Bruguiere (B.) Gray, 1858. Anterior end with a lamellae. B. frill; — Section posterior end simple. B. s. s. (synonym Clepsydra of long tubules; posterior 860). — Section Warnea posterior end with a few folded (W.) vaginiferus (Lamarck). >p Fig. 860. Anterior part of the tube of Brechites annulatus (Deshayes), with the small shell attached within HI. STIRPS it. POROMYACEA Shell free, nearly or completely equivalve, smooth or beset with small margin with or without spinules; ligamental cartilage with lithodesma; hinge mantle sinus not or weakly developed; siphons short as a rule; gill laminae narrow, net-shaped or modified into a horizontal septum pierced by minute sieves or rows of perforations; foot without byssus. Inhabitants of the deep sea. teeth; 1. Family VERTICORDIIDAE Shell exteriorly beset with spinules, interiorly nacreous, in most cases roundish, sometimes distinctly ribbed; hinge margin often with a bulging 1427 tooth anterior to the cartilage in the right valve. Mantle with a short anal siphon and a scarcely elongated, but sometimes very wide, incurrent which aperture, is surrounded by tentacles; gill laminae narrow, net- shaped, in most cases enclosed in an incomplete septum; foot small, with a groove; labial palps rudimentary; gonads hermaphroditic. Lyonsiella (M. Sars, 1868) G. O. Sars, 1872 944 Shell roundish or more somewhat longish, thin, sometimes inflated; umbo or less close to anterior end; right valve without hinge tooth, left with a weak thickening of the margin below the umbo; mantle line not indented. The gill septum and mantle form a of valve, which can form or sort prevent a communication between the upper and lower mantle cavity. A few species, in all Subgenus Thracidora umbo longish; seas. Iredale, 1924. close to the center, (Hedley); the South African L. Shell somewhat compressed, scarcely elevated. agulhasensis Jaeckel & L. arenosa (T.) Thiele may also belong here. Subgenus Lyonsiella umbo s. s. Shell greatly bulging, rounded rectangular; close to the anterior end, inflated; sac. L. (L.) abyssicola M. Sars (Fig. genus Proagorina for the Australian species is different inhalent opening moderately septum united with the large, situated at the posterior end; gill 861). L. Iredale, visceral 1930, proposed a quadrata Hedley; however, so similar to L. abyssicola that it can hardly be placed this in a group. Subgenus Laevicordia Seguenza, 1876. Shell roundish, somewhat higher than in long; incurrent opening very wide; gill most cases septum not united with the visceral sac. L. (L.) insculpta (Jeffreys). Fig. 861. Outer and inner side of the shell of Lyonsiella abyssicola (after Sars). M. Sars 1428 Halicardia Dall, 1895 Shell fairly large, heart-shaped, with radial folds, the largest of which granulose; hinge teeth rudimentary; at the end, externally forms an angle lithodesma asymmetrical, narrow, right limb longer than the left. Mantle with very wide incurrent opening, which bears several large tentacles, and small opening for the foot; labial palps thin, smooth; foot with a small posterior process; the gills are attached only at the posterior part of foot, without outer lamina. & H. flexuosa (Verrill Smith), in the Atlantic Ocean. Halicardissa Dall, 1913 Shell similar to that in Halicardia with a deep lunule; are largely free, incomplete; few strong folds and small with a strong cone-shaped tooth. in the right valve with direct and indirect lamellae; palps and foot having labial The gills septum thin and more resemblance with the usual condition, the latter without posterior process. H. perplicata (Dall), near the Galapagos Islands. Verticordia (Gray, Synonyms Hippagus Philippi, 1844, J. Sowerby, 1844 non Lea, 1833; Iphigenia O. G. 1817; Hippella Morch, 1850, non Schumacher, Costa, 1842) Shell fairly small, closed, beset with spinules, in and with 945 lunule umbo more radial folds; more or shaped tooth; less depressed; or less elevated, anteriorly directed; right valve in most cases with a cone- valve in most cases with projecting margin of the left ligament internal, with fairly large lithodesma. lunule; Many species, in various seas, often in deep water. Section Vertisphaera Iredale, 1930. Shell unribbed. — uniformly — (Iredale). folds, Hedley. umbo 1 1861. most cases roundish 1930. Vertambitus Iredale, Section granulose; umbo Shell sharply projecting. V. (V.) with V. cambrica flat (V.) radial vadosa Section Haliris Dall, 1886. Shell with numerous, dense folds; not sharply projecting. 930 (setosa Hedley), is V. (//.) fischeriana Dall. Setaliris Iredale, scarcely different. — Section Trigonulina Orbigny, 1845. Shell compressed, partly ribbed; hinge tooth longish. V. (T.) ornata Orbigny (Fig. 862). — without hinge tooth. Iredale, 1930. Section V. Verticordia Lunule very small, tubercular hinge tooth. V. (S.) ericia s. s. Shell with strong folds, — Wood. Section Spinosipella covered by the umbones, with a Hedley = deshayesiana P. Fischer. (V.) verticordia S. 1429 Fig. 862. Right shell/valve of Verticordia (Trigonulina) ornata Orbigny, inner and outer side enlarged (after Verrill). Euciroa Dall, 1881 Shell fairly bulging, with large, in most cases oval or roundish, more or numerous spinose radial umbo ribs; less close to the center; right valve with a tubercle-shaped tooth, left with projecting margin of the lunule and of the posterior dorsal area; an indentation of the hinge margin corresponds to the right tooth. The mantle has a wide opening for the foot and scarcely elongated siphons, the lower of which is somewhat wider than the dorsal, surrounded by several tentacles; a ventral part of the mantle contains strong muscles; foot well developed, in most cases pointed; labial palps smooth, elongated, the center with in vesicular swellings; the ventrally slightly projecting gills are united exteriorly with the mantle and posterior to the foot with one another and with the siphonal septum. A few species, mainly Section Euciroa elegantissima (Dall). s. — s. in the Shell Indo-Pacific region, in the deep sea. roundish or transversely oval. E. (E.) Section Acreuciroa Thiele, 1931. Shell posteriorly pointed beak-shaped. E. (A.) rostrata Jaeckel & Thiele (Fig. 863). With M. Fig. 863. Right shell valve of Euciroa (Acreuciroa) rostrata Jackel Thiele & 1430 2. 946 Family POROMYIDAE Shell fairly small and thin, roundish or oval, interiorly nacreous, often with a hinge tooth of the right valve; cartilage fairly weak, lying just below the exterior ligament. Mantle ventrally widely open; the short siphons surrounded by a ring of tentacles, the lower one has a large valveprocess in the interior; its retractors are in most cases scarcely like developed; foot with ventral groove, sometimes with weak byssus; labial palps large, the rudimentary gills on either side forming 2 or 3 small sieves or rows of perforations in most cases muscular septum; gonads hermaphroditic (Fig. 864). Fig. aa, 864. Poromya (Cetoconcha) butoni Prashad. Animal seen from the left side, after removal of the left mantle lobe. ap, anterior and posterior adductor muscle; ba, bp, anterior and posterior sieve; f, retractor foot, p, outer of the foot; rs, and inner - labial palp; rs„„ retractors gill and posterior v, valve of the rpa, rpp, anterior of the septum gill s; incurrent siphon (after Pelseneer). The animals inhabit the deep sea. Poromya H. Forbes, 1844 Synonyms Embla Loven, 1846; A. Adams, 1856. Thetis (err. non & Shell in most cases inflated, roundish, posteriorly and often with an edge; umbo projecting, close on either side with 2 pore sieves. A few species, in all seas. J. Sowerby, 1826) somewhat truncated to the center. Gill septum 1431 Section Poromya s. Surface finely spinose; hinge tooth distinctly s. developed; no mantle sinus. P. (P.) granulata (Nyst 865). According to Dall, Ectorisma Tate, therefore E. granulata Tate upholds contrast, Questimya for P. was & undosa Hedley Westendorp) by Hedley; (Fig. Poromya, 1892, belongs to called P. illevis this genus; the latter in & Iredale, in 1930 also proposed the genus Petterd. — Dermatomya Section Dall 1889. Surface not spinose. Hinge margin strong; a mantle sinus developed. P. (D.) mactroides Dall. — Section Cetomya Dall, 1889. Surface spinose; hinge tooth rudimentary; no mantle sinus. P. (C.) elongata Dall. Fig. 865. Poromya granulata (Nyst & Westendorp). Cetoconcha Dall, 1886 Synonym Shell Silenia Edg. Smith, oval, 1885, non Mulsant, center; hinge tooth rudimentary; without mantle sinus. on either side contains 3 groups of pores; those in the are transversely, in the posterior C. Few bulla (Dall). 3. Shell inflated, row longitudinally The gill septum two anterior rows directed. species, in the deep sea. CUSPIDARIIDAE Family posteriorly beaked, most cases 1873. with more or less elevated umbones situated in the smooth or variably sculptured, interiorly not nacreous; thin, in hinge margin with or without teeth; mantle sinus fairly shallow. Siphons in most cases short; at the base of the lower one on either side with 2 tentacles, closed by a membrane with 3 tentacles; gill labial septum its inner end a small aperture; above the upper siphon are fairly thick, on either side with a row of 4 or 5 pores; palps small or absent; foot in most cases with a groove; sexes separate (Fig. 866). Cuspidaria Nardo, 1840 Synonym Neaera Gray, 1833, non Robineau-Desvoidy, 1830. 1432 Ligament projecting below the hinge margin or ventrally, with small lithodesma; hinge margin sometimes with main or lateral teeth, sometimes toothless. Numerous species, in the deep sea in all oceans. Fig. 866. Ventral view of Cuspidaria convexa Prashad, without shell; mantle lobes largely cut away. aa, anterior adductor muscle; as, internal m, mouth opening; p, labial palps; median of the 5 pores opening of the current siphon; gill septum; in the septum s, Subgenus Pseudoneaera Sturany, f, foot; excurrent siphon; so, the si, (after Pelseneer). 1900. Shell short beaked, concentrically sculptured; hinge margin on the right with 2 diverging teeth, on the ligamental pit; left with an indistinct denticle anterior to the short mantle widely open; ventral siphon long. C. (P.) thaumasia (Sturany). Subgenus Myonera Dall & E. Smith, 1886. Shell in most cases short beaked, often with a few radial and concentric folds; hinge margin toothless. C. (M.) paucistriata (Dall). Subgenus Halonympha Dall beaked, & smooth or concentrically one pointed tooth; ligamental pit E. Smith, striated; short; 1886. in Shell fairly a half-moon-shaped lamella surrounds the attachment of the posterior adductor muscle. claviculata (Dall). short the right valve with C. (//.) 1433 Subgenus Liomya A. Adams, 1864 (Leiomya). Shell short beaked, smooth or concentrically striated; ligament very oblique; hinge margin on either side with one tooth and on the right with one anterior and posterior lateral lamella. C. (L.) Subgenus Tropidomya Dall Jeffreys, & non Troschel, 1881, adunca (Gould). E. Smith, 1 886 (synonym Tropidophora 1847). Shell margin on either side with one tooth. C. Subgenus Luzonia Dall & E. similar to Liomya; (T.) Smith, hinge abbreviata (Forbes). 1889. Shell short beaked, concentrically striated; right valve with one tooth below the umbo. C. (Z,.) philippinensis (Hinds). Subgenus Plectodon Carpenter, 1864. Shell rough as in Poromya; hinge margin with a tooth-like thickening; ligamental pit posterior to and below the umbones; ends of the siphons protected by a leather-like ring which is broadened on the sides. C. (P.) scabra (Carpenter). 948 Subgenus Rhinoclama Dall & E. Smith, 1886 (synonym Rhinomya A. Adams, 1864, non Robineau-Desvoidy, 1830). Surface concentrically striated, not granulose; hinge margin toothless. C. (R.) adamsi nom. nov. = philippinensis A. Adams non Hinds. Subgenus Vulcanomya Dall, 1886. Surface concentrically striated; hinge margin on the right with small, fairly thick, anterior and posterior lateral lamellae; pit small, Fig. on the left only with a similar anterior one; ligamental below the umbones. C. situated (V.) smithi Dall. 867. Inner side of the right shell valve of Cuspidaria cuspidata (Olivi). Subgenus Cuspidaria lamella in the right Cuspidaria s. s. s. valve; Shell cuspidata (Olivi) (Fig. (synonym Spathophora s. Hinge margin with only one posterior posterior beak variable in length. Section smooth or concentrically sculptured. C. (C.) 867). Section Cardiomya A. Adams, 1864 — Jeffreys, 1881). Shell with radial folds. C. (C.) gouldiana (Hinds). Class CEPHALOPODA The cephalopods are exteriorly symmetrical animals, which seldom possess an external chambered spiral shell, in most cases a calcareous or 1434 horny The shell below the dorsal integument; sometimes they have no foot of the remaining mollusks is funnel-shaped tube, which serves the animals for a life. shell. here as a rule modified into a swimming mode of large head in most cases contains highly developed eyes and The bears strong arms, which are as a rule beset with suckers used for grasping prey. The mantle encloses a ventral space, which contains the two (doubled only in Nautilus) as well as the anus and the openings gills of the kidneys and the gonad. The mouth, surrounded by the arms, leads into a strong buccal mass with a dorsal and a ventral jaw and with a which radula, only very seldom reduced; a pair of salivary glands is nearly always present; in dibranchians also a more or less is large, occasionally paired poison gland; below the tongue lies an organ of taste; the intestinal system has a large digestive gland; the rectum is in cases short and opens into the mantle cavity behind the funnel. bilaterally symmetrical; that of Nautilus shows nervous system is similarity with that of bivalves, because most The some has cerebral, pedal, and it visceral ganglia, but in addition buccal ganglia are also present; in the remaining cephalopods the pedals are fused with the visceral ganglia; the arms have received a strong nervous system, and a pair of ganglia (stellate ganglia) are developed for innervation of the mantle musculature. The blood vascular system pericardium; not traversed is it is well by developed; the heart Nautilus, 2 in the remaining cephalopods. and decapods is lies in a the intestine and has 4 auricles in The pericardium in Nautilus considerably widened and forms a body cavity which surrounds the viscera; in octopods, on the other hand, the true pericardium is reduced and the part associated with the gonads forms 2 flask-shaped pouches containing the glandular processes of the gill-hearts and opening into the kidneys through ciliated funnels. Corresponding to the gill 949 vessels, 4 kidneys The body cavity, present. the in Nautilus, 2 in the remaining cephalopods are sexes are always separate; the single into which the gonad lies in ripe products first enter or beside and are then discharged through the gonoducts. These often remain paired in the females, whereas in the male one of them is nearly always reduced, the other one has glands which produce spermatophores. This duct opens often with a penis-like process, although the transfer of spermatophores to the female is accomplished by more or less modified arms. The more or less large eggs are yolk-rich; they are laid sometimes in very large quantities and are often attached on the substratum or on seaweed; Argonauta they are kept in a thin calcareous shell. in 1435 I. Among Schwarz, Subclass TETRABRANCHIA the primitive cephalopods with an external shell (Ectocochlia Tomochonia Haeckel, 1896; Protocephalopoda Grimpe, 1894; 1922), of which a large number of species populated the seas in earlier times, only the genus Nautilus has survived to the present day. The is bilaterally symmetrical, spirally coiled, shell divided by several partitions perforated in the center; these septa are posteriorly bulging and produced into a small funnel-shaped process at the perforation; the inner side is nacreous, the outer side porcellaneous. Half of the body whorl represents the living chamber of the animal, which in directed; a thin process of the posterior ventral side its outwardly is end traverses the entire series of chambers. The mantle forms a dorsal lobe, which adjoins the penultimate shell whorl, ventrally it forms a broad membrane covering the the posterior part of the funnel. The latter consists gills and of 2 large lobes, which are anteriorly and at the sides free and enrolled toward each other, so that they form an anteriorly narrowed tube, open below in which tongue-shaped anteriorly directed valve head bears numerous annulated cirri in front lies a of the center. The large with their sheaths, which are arranged into an outer and an inner system. The sheaths of the dorsal arms are considerably enlarged and fused together membranous cephalic hood, which the animal on is and 7 form a thick when retracted into the shell; the outer system comprises 19 either side, central to largely covers the shell aperture of which 4 smaller ones are the outermost; 8 in the sexes; in the female innermost row. The inner system differs it lie in the two consists of 2 lateral parts with 12 cirri each and a ventral bilobed part, which on either side forms a lobe with 12-14 and a median indentation with a few lamellae, in a arms in the this ventral part is cirri sunken pocket between the buccal mass and the body wall, the outer wall of which forms fine lamellae, by the male. In the male the to which the spermatophores are attached lateral parts of the inner system dorsal section with 8 cirri and a ventral one with 4 adult animals, the ventral is part cirri; form a the latter, in on one side modified into a copulatory organ (spadix); is borne in a deep membranous which has numerous lamellae. An annulated of the inner system sheath, the ventral side of cirrus is present anterior and posterior to the eye. The eyes are in the form of open vesicles without lens and vitreous body. Below the eye a finger-shaped process with 2 pits 950 is present, probably a rhinophore. The strong buccal mass contains powerful jaws and a broad radula, in which each transverse row consists of 13 plates; the central plate has moderately long pointed cutting edges, the 3rd and 5th of the lateral plates have long curved edges, the remaining ones have short cutting edges (Fig. 868); the liver consists of 4 lobes; the intestine forms one loop. In the mantle 1 1436 cavity on either side their bases. lie 2 pinnate Corresponding to each heart and a renal sack; they open gills, attached to the body with only a spindle-shaped auricle of the gill is into the mantle cavity, the lower pair immediately beside the openings of the pericardial ducts. The pericardium communicates with the wide body on the genital is septa. Only the cavity, in right which the gonad gonoduct is borne lies, developed, the left one modified into an internally closed vesicle. Whereas the oviduct short and wide, the sperm duct a spermatophore gland, and it is narrow and coiled, is in association with opens into the mantle cavity with a penis- process behind the funnel. The large eggs are attached to the like substratum. Fig. 868. Half radular row of Nautilus pompilius Linne; under lateral it one plate in view. Fanuly NAUTILIDAE 95 Shell coiled in one plane, externally smooth; septa perforated in the center. Nautilus Linne, 1758 Characters of the family. N. Pacific pompilius Linne (Fig. 869). Few living species, in the Indo- region. II. Subclass DIBRANCHIA Recent cephalopods without external shell (Endocochlia Schwarz, 1894; have 2 Gamochonia Haeckel, 1896; Metacephalopoda Grimpe, 1922) gills as in the bivalves and the zeugobranch snails. The shell is here inside the body, and in most cases lies below the dorsal integument. It is seldom calcified; only in Spirula it has a form reminiscent of Nautilus, being spiral, cylindrical, distinctly chambered and is pierced by 1437 950 Fig. 869. Nautilus pompilius Linne, seen from the right side, the shell sectioned in the center. A V, anterior muscle band; C, DM, of the funnel; funnel; Ho, cephalic hood; and posterior it cirri; J, spire of shell; Cf , CR, posterior part O", tentacles attached anterior S, living process of the body running through; right shell muscle; Sp, last ventrally coiled, Csh, sheaths of the PV, posterior muscle band; to the eye; shell; Si, siphuncle; SI, a siphon, but cirri; dorsal part of the mantle; E, eye; F, anterior part of the chamber of the SM, attachment of the septum; VM, ventral part of the mantle (after Griffin). small, enclosed in the posterior part of the body, and is completely separated whorls. with different in sepiids, where it Its form is very forms a dorsal plate with a posterior spine, whose inner side has numerous fine septa. In most cases the shell is a more or less elongated, often plume-shaped plate, sometimes posteriorly with a small cone-shaped chamber or a solid apex. In a few groups the shell has become rudimentary, occasionally completely lost in adult animals. The mantle encloses the posterior half of the body which horny, contains the viscera and is rather variable in the gills and part of the funnel, with which form and ventrally surrounds it is in most cases joined by knob-like cartilaginous elevations, seldom firmly fused. A pair of membranous fins are in most cases developed on the sides of the mantle. The funnel is a closed, anteriorly narrowed tube, whose anterior part is in most cases sunken into a depression interior as a rule has a valve of the head and which in the and glandular bulges. The large head nearly 1438 always contains highly developed eyes and bears 8 more or less strong prehensile arms bearing suckers, to which are added in decapods a pair of longer raptorial arms, which however are reduced The arms often possess more or unpaired webs on the outer side are ones on the inner side as protective most extensive in a in a few genera. membranous webs; known as swimming webs, paired webs. Such membranous webs are less extensive few octopods, where they occupy nearly the entire intervening spaces to the ends of arms. In octopods the suckers developed on the arm side facing the mouth are unstalked, radially organized, and arranged in one or two rows; in decapods they are stalked, in most cases distinctly bilaterally symmetrical, and with denticulate chitinous rings, which are sometimes modified into strong hooks, they are arranged in most cases in 2 or 4 rows. Females of Argonauta bear a strong lobe-shaped expansion on the uppermost pair of arms, clasping a thin, spirally coiled, calcareous shell which is not firmly attached to the as a container for the laid eggs. less modified arm, more seldom a the female; such an arm, 952 The male animals known pair, for transfer is spindle-shaped pillars, it is most radially directed is often supported by toward the arms, to which they are joined by attachments; extending from these delicate strikingly detaches from the animal. The surrounded by a membrane, which which are of spermatophores to as the hectocotylus, developed in a few octopods, where mouth opening body and serves mainly as a rule use a more or pillars are membranes, which form pocket-like, sometimes partly closed spaces. Besides chromatophores and glands, the integument of cephalopods sometimes contains light organs. The highly developed eyes are sometimes completely covered by the external integument of the body, sometimes the eye cavity remains open; sometimes the eyes are elevated on more or less long stalks; only extremely seldom they are rudimentary. Statocysts and small pit-shaped olfactory organs are present. The central nervous system forms an esophageal ring, in which the pedal and one another, whereas the arm ganglia are fused with pedals; the ganglionated arm nerves commissure; a pair of ganglia are joined with lie visceral ganglia anterior to the one another by a ring (stellate ganglia) innervate the musculature of the mantle. The buccal mass contains a of which as a rule have 7 there pair of horny jaws and a radula, the rows plates, besides which, mainly in the Octopoda, another pair of toothless marginal plates. In most cases the plates is have more or less long, pointed, plate has central simple cutting edges. Sometimes the a small accessory cusp on either side, seldom the neighboring plates also bear accessory cusps; in Gonatus fabricii there is one less pair reduced. of plates and in cirroteuthids and Spirula the radula The tongue and the subradular organ are surrounded is by the 1439 lamellae of a pouch, the free surface of which bears a cuticle beset with thorns. The and below the esophagus salivary glands are paired of a poison gland, which exit duct leads into the in lies the sometimes paired. The esophagus is most cases sack-like main stomach, whereas in most cases single liver and a pancreas open into an accessory stomach; the intestine is short, into which lost. is terminal part opens the exit duct of the ink sack, its most strongly developed The two cases leaves only its in sepiids; in cirroteuthids outermost tip free. In heart. has been Corresponding to them, the heart has 2 auricles and between the veins and the gill it attached to the mantle by a band, which in most gills are gills on either side lies a decapods, the pericardium with the body cavity has an extent similar to that in Nautilus; in octopods the pericardium reduced is The two kidney sacks are separate in octopods, united in decapods. The oviducts are as a rule paired, seldom only one is developed; on the other hand, the sperm duct and the gonadal part is also greatly narrowed. is nearly always unpaired; it forms a spermatophore gland, then a so- called finishing gland and a spermatophore sack (Needham's sack), at the end with a muscular or glandular penis-like process. Order I. Cephalopods with an DECAPODA internal calcareous or horny shell, seldom rudimentary, with 8 arms and 2 longer tentacles, which however are sometimes reduced; suckers stalked, often denticulate horny ring; buccal distinct tips mantle with 953 lateral fins; I. Shell calcareous, in most cases bilateral, membrane with 6-8 more with an or less kidney openings close to the anus. STIRPS SEPIACEA homy, or absent; body fairly massive, in most cases without light organs; arms never armed with hooks; eye cavity in most cases closed; buccal membrane without attachments with the arm bases; only one oviduct developed; accessory nidamental glands present. 1. Shell calcareous, Family SPIRULIDAE enclosed in the posterior part of the animal, cylindrical, spiral, with about 2 A separated whorls, coiled ventral ward, l chamber and many chambers separated by arched septa with a continuous, ventral siphuncle (Fig. 870). Body with a nearly sphere-shaped (Fig. initial 871) cylinder-shaped, with small, roundish, nearly terminal fins and a posterior annular bulge surrounding a luminous organ; eyes with an 1440 X Fig. 870. Shell of Spirula spirula (Linne), double Fig. 871. Spirula spirula (Linne), in dorsal (after open six lid fold; size. view Chun). arms moderately strong, with many, at the base with up to rows of small, short-stalked suckers and joined with one another by broad membranous webs; the two ventral arms in the male are hectocotylized, without suckers and without connecting web; they are different from each other; the right one is channel-shaped, spoon-shaped at the end with a pair of claw-shaped points; the left one cylindrical, at the end with a few variously formed processes and a few small points (Fig. 872); tentacles only partly retractile, considerably longer than the arms. The buccal mass 1441 Fig. 872. Ventral view of the head and the arms of the male of Spirula spirula (Linne) (after Kerr). contains no radula; the posterior gland is mid-gut traverses the urine sack which developed only on the left single; liver lobes separated; the is open with 2 papillae; oviduct besides the true nidamental side; glands, accessory glands are also present. Spirula Lamarck, 1801 Synonyms Lituina Link, 1806; Lituus Gray 1849. — Characters of the family. S. spirula (Linne), in 954 2. warm seas, living bathypelagically. Family SEPIIDAE Shell calcareous, forming a dorsal plate, often with a posterior thorn, on the ventral side with a mass of vertical pillars, the last-formed fine oblique septa supported by small septum forming the anterior part of this bulge, followed by the margins of the remaining septa; a siphuncle is by a flat posterior pit, delimited laterally and sometimes also ventrally by a margin, the so-called fork. Body more or less massive, indicated — 1442 somewhat compressed, with clubs with 4-8 rows of suckers; membranes; eye cavity nearly arms with 2-4 tentacular fin lateral completely closed; with a secondary lid fold; completely retractile into tentacles pockets; ventral arms with muscular fin membranes; ink sack very large; left ventral arm hectocotylized. Radular plates without accessory cusps. Sepia Linne, 1758 Mantle sack without glandular pores. Numerous species, in various seas. Section Crumenasepia Iredale, 1926. Shell medium-sized, elongated end of the bulge and which oval, with broad fork covering the posterior forms a broad and deep horny pocket. hulliana (Iredale). (C.) S. Section Solitosepia Iredale, 1926. Inner pocket well developed; posterior thorn keeled. S. (S.) liliana (Iredale). 1 — Section Mesembrisepia Iredale, (M) macandrewi 1884 (Ascarosepion) 926. Shell similar to the preceding; thorn cylindrical. Iredale. —Section Ascarosepia Rochebrune, (synonym Amplisepia Iredale, 5". Shell large, posteriorly narrowed, 1926). without thorn; bulge anteriorly swollen, posteriorly depressed; posterior margin elongated and thickened; pocket verreauxi Rochebrune. —Section fairly deep with warts. S. Lophosepia Rochebrune, (A.) 1884 (Lophosepion). Shell without thorn, posteriorly rounded; bulge elevated to form a massive comb. Orbigny. S. (L.) lefebrei — Section Acanthosepia Rochebrune, 1884 (Acanthosepion). Shell with strong, projecting thorn; posterior margin freely projecting strong. S. (A.) aculeata Hasselt. — downward; fork freely projecting, Section Ponderisepia Iredale, 1926. Shell very large and thick, with very large thorn; bulge strongly swollen. S. (P.) eclogaria (Iredale). —Section Rhombosepia (Rhombosepiori) (synonym Parasepia Naef, Rochebrune, 1884 Shell slender oval, 1923). with posterior wings; marginal lines of the lamellae of the bulge on the — sides with regular angles. S. Rochebrune, Section Doratosepia (/?.) elegans Orbigny. 1884 (Doratosepion) (synonyms Andreaesepia Grimpe, 1922; Arctosepia Iredale, 1926). Body and shell the slender, latter posteriorly pointed, with strong thorn and small, projecting wings; ends of the arms elongated whip-like. Platysepia Naef, S. (D.) andreana Steenstrup. — Section 1923. Shell fairly broadly oval, with terminal thorn; ventral margin very blunt closely leaning on the thorn; fork low, tipped over. S. (P.) esculenta Hoyle. Section Sepia — s. s. in part (synonym Eusepia Naef, 1923). Shell broadly oval; fork recurved, spreading over the posterior; indistinctly winged dorsal shield; few suckers of the tentacular club distinctly enlarged. S. (S.) officinalis Linne. Spathidosepia Rochebrune, 1884 (Spathidosepion) is related; shell fairly short oval, — 1443 uniformly rounded, without thorn, S. 955 (5.) tuberculata Lamarck. lateral margins posteriorly very broad. — Section Decorisepia Iredale, 1926. Shell moderately broad, anteriorly pointed with cylindrical thorn; posterior margin broad, weakly calcified, without pocket. S. (D.) rex (Iredale). Section Glyptosepia Iredale, 1926. Shell similar to the preceding group; long and strongly keeled. thorn (G.) S. opipara (Iredale). — Section Tenuisepia Cotton, 1932. Shell small, narrow, with moderate, cylindrical pocket rudimentary. thorn; S. (T.) mira (Cotton). — Section Metasepia Hoyle, 1885. Shell rhomboid, without thorn; pocket shallow; tentacular club with unequal suckers. S. (M.) pfefferi Hoyle. This group was considered as a genus by Grimpe. Sepiella Gray, 1849 Synonym Diphtherosepion Rochebrune, 1884. Shell without thorn, slender oval, posteriorly with a broad margin, without distinct pocket; the posterior end of the shell is overlain by a spacious folded glandular pocket, which opens posteriorly between the fin membranes; tentacular club with Few ornata (Rang). S. 8 regular species, in warm rows of small suckers. seas. Hemisepius Steenstrup, 1875 Synonym Hemisepion Rochebrune, 1884. Shell weak, calcified only in the posterior half, posteriorly pointed; animal fairly small; side with a suckers; mantle short and broad, on either side on the ventral row of about 1 2 glandular pores; arms short, with 2 rows of tentacular clubs hectocotylized arm is short, with several small suckers; the broadened; suckers largely reduced, some of them enlarged on the distal part. H. typicus Steenstrup, near South Africa. 3. Family SEPIADARIIDAE Mantle margin dorsally fused with the head, with broadly attached without shell; arms with distinct protective membrane, on their fins, distal part with 4 rows of suckers; the left ventral arm hectocotylized. Sepioloidea Orbigny, 1845 Body is short; fins nearly as long as the mantle, the dorsally fused to the head and laterally fringed, margin of which ventrally it has 1444 numerous pores; arms joined by a fairly broad membrane, which is absent only between the ventral ones; the left ventral arm of the *f with transverse channels and conical papillae distally, without suckers. S. lineolata & (Quoy Gaimard), near Australia. Sepiadarium Steenstrup, 1881 Fins short, attached closer to the posterior end; mantle joined with the funnel by a muscular band; the funnel contains a valve only in the 2, distally with 4 rows of suckers; hectocotylus ; arms proximally with distally without suckers; clubs S. of the tentacles with very small suckers. kochii Steenstrup. 3 species, near eastern and southern Asia and Australia. 4. Animals less large, in SEPIOLIDAE Family most cases small; mantle rounded fins attached rudimentary; inserted in the cornea 956 short, rounded, with somewhat above the is more or center; shell a lid fold, which does not enclose the pore; arms without protective webs, with spherical suckers; tentacles retractable into pockets; radular plates without accessory cusps; one or both dorsal arms or one laterodorsal arm hectocotylized. A. Subfamily Rossiinae Mantle margin dorsally free, with neck cartilage and distinct shell rudiment; fins rounded; the basal parts of the arms joined by a protective membrane; the marginal suckers on the central part of the arms strikingly enlarged; tentacular club more or less broadened, with a swimming web; one or both dorsal arms in the *f hectocotylized; without luminous glands in the mantle cavity; funnel with a valve. Living on the substratum. Rossia Owen, 1834 Synonym Epitychusa Gistel, 1848. Characters of the subfamily. Subgenus Semirossia Steenstrup, 1881. Arms with 2 rows of suckers; only the left dorsal arm hectocotylized. R: (5) tenera (Verrill). A couple of species, along the Atlantic coasts of America. 1 Subgenus Allorossia Grimpe, 1922 (synonym Franklinia Norman, 890, non Jerdon, 1 863). Arms with 2 rows of suckers; both dorsal arms hectocotylized. R. (A.) glaucopis northern seas. Loven (Fig. 873). Few species, in the 1445 956 Fig. 873. Rossia (Allorossia) glaucopis Loven in dorsal view (after Sars). Subgenus Austrorossia Berry, 1918. Arms with 2 rows of suckers, the o* a few suckers are enlarged on all in arms; tentacular club very long, with very numerous and very small suckers. R. (A.) australis Berry. A couple of species, near Australia and East Africa. Subgenus Rossia s. s. Arms with 4 rows of suckers; tentacular club moderately long; suckers variable few northern in size. R. (/?.) palpebrosa Owen. A species. B. Subfamily Heteroteuthinae Mantle margin dorsally free or fused with the head; fins large; arms joined by a fairly broad membrane, the dorsal ones distinctly shorter than the lateroventral ones, with 2 rows of suckers, pair are strongly enlarged; tentacular clubs some of which on the 3rd scarcely broadened, rudimentary swimming web; massive light glands lie with on the ink sack near the center. Living pelagically. Heteroteuthis Gray, 1849 Synonym Stephanoteuthis Berry, 1909. Body somewhat laterally compressed and margin dorsally free, ventrally largely posteriorly pointed; mantle covering the funnel; eyes without 1446 '957 lid fold; dorsal and tentacles long thin, with very small suckers; in the right arm swollen, and the 3rd arms have 2 or 3 greatly enlarged suckers. Few H. dispar (Ruppel). species, in warm seas. Necloteuthis Verrill, 1883 Animal small; mantle posteriorly rounded, short, below with a large anterior lobe which covers the funne/ and head; eyes with round pupils; arms small, on the distal parts with cone-shaped elevated suckers (?cf); tentacles long and slender. N. pourtalesi Verrill, in the Atlantic Ocean near Barbados. Iridoteuthis Naef, 1912 Animal small, roundish; head relatively long; mantle short and rounded, with large wing-shaped fins; mantle margin dorsally fused with the head, ventrally produced far forwardly; arms short; tentacles fairly long; light glands weak. /. iris (Berry), near the Hawaiian Islands. Stoloteuthis Verrill, 1881 Mantle fairly short, broadly fused with the head, without shell, with large rounded fins attached to the anterior part of the mantle; arms short, with 2 or 3 enlarged suckers on the 2nd pair and in the d with a few larger suckers small S. on the dorsal pair; tentacles moderately long, with very suckers. leucoptera (Verrill), on the North American east coast. Sepiolina Naef, 1912 Neck band in size in the fairly broad; 1 d ; suckers uniformly small in the ?, unequal both dorsal arms with small suckers without special copulatory organ; light organ disk-shaped. S. nipponensis (Berry), near Japan. C. Subfamily Sepiolinae Mantle margin dorsally fused with the head, without neck arms for the most part with 2 rows of suckers; in the c? cartilage; the left dorsal 1447 arm has a peculiar copulatory organ near the base, and on the remaining orbital pores open; light glands arms the suckers are enlarged; may be present. Euprymna Without shell; Steenstrup, 1887 neck band broad; protective membrane between the 3rd and 4th arms; suckers distinct only the base and on the point of at the arms in 2, otherwise in 4 rows; tentacular club with very small or rudimentary suckers; light glands present. morsei E. near eastern and southern Asia. (Verrill), Sepiola Leach, 1817 Synonym Fidenas Gray 1849. weak shell in most cases present; arms with 2 rows of A only occasionally in 4 rows the left dorsal at the tips arm modified; of the ventral arms; in the suckers, d only tentacular club with 8 suckers rows; light glands present. A few species, Section Sepiola 958 2 in various seas. s. rows of suckers. Grimpe, (//.) Buccal funnel (synonym Eusepiola Grimpe, 1922). Arms with intermedia Naef. (S.) Tips of the ventral 1922. suckers. S. s. S. atlantica Orbigny. 7-partite. S. — — Section Heterosepiola arms with 4 rows of very small Section Hemisepiola Grimpe, 1922. (//.) pfefferi Grimpe. Rondeletiola Naef, 1921 Synonym Rondeletia Naef, Shell reduced; ventral 1916, non Goode & Bean, 1894. arms with 2 rows of suckers; 2nd arms with a few enlarged suckers of the ventral row; ink sack pear-shaped; light glands in both sexes situated close to the midline. R. minor (Naef), in the Mediterranean Sea. Sepietta Naef, Synonym Sepidium Levy, Shell rudimentary; of suckers; in the c? 1912 1912. arms and tentacles long; ventral arms with 2 rows the left dorsal arm broadened and hollowed between the sucker rows; ink sack slender pear-shaped; without light glands. S. oweniana (Orbigny), in European seas. 1448 1881 Inioteuthis Verrill, Neck band and unequal /. japonica narrow; suckers uniformly small in the fairly in the <$; Verrill, near Japan. Family IDIOSEPIIDAE 5. Body without ?, large light glands absent. shell, moderately long; fins fairly small, attached near the rounded or pointed posterior end; dorsal mantle margin free, without cartilaginous support; arms short tentacles fairly small, with 2 or in the c? and strong, with 2 rows of suckers; 4 rows of suckers; eyes without lid fold; the two ventral arms are hectocotylized in different ways; both oviducts are present, although only the left one is in use. ldiosepius Steenstrup, 1881 Synonyms Microteuthis Ortmann, 1888; Naefidium Grimpe, 1920. Characters of the family. pygmaeus Steenstrup. Few species, near eastern Asia and Australia. the body form and the two ventral hectocotylized arms, the species show similarity with Spirula, but have no shell. /. By STIRPS LOLIGINACEA II. Shell horny; mantle with large, as a rule terminal fins and with free margin; arms and tentacles with suckers; tentacles not retractable into pouches; cornea with an anterior pore. Family 1. LOLIGINIDAE Shell feather-shaped; fins roundish and terminal or extending farther anteriorly; buccal 959 membrane as a rule with 7 tips and in most cases with a few small suckers; the 3 median radular plates with a point on the outer corner of the base; in most cases the left ventral Loliolopsis Berry, Mantle more slender fin; in the buccal membrane with arm is hectocotylized. 1929 9 than in the d, with terminal roundish 7 short tips and few suckers; shell very thin, anteriorly narrow, then distinctly broadened and posteriorly pointed; d with longer arms, both ventral ones hectocotylized, the left one with a 1449 lobe on the inner margin, the right one greatly elongated, with few basal suckers and with a comb-shaped row of small points on the distal part; tentacles fairly short. chiroctes Berry, near California. L. Loliolus Steenstrup, Animal and fairly small delicate; mantle short, rounded; rounded; gladius with broad vane; adductors; suckers without hectocotylized throughout its 1856 funnel fringed length, fin anteriorly without externally visible membrane; left ventral arm with a cuspidate comb, without suckers; tentacles fairly long and thin. L. Few typus Steenstrup. species, in the Indian and Pacific Oceans. Lolliguncula Steenstrup, 1881 Animal fairly small and strong; fin elliptical, fleshy, occupying about half the mantle length; buccal membrane with suckers; the spermatophores are attached in the mantle cavity in the vicinity of the left gill. L. brevis (Blainville), on the American coast. Loligo Lamarck, 1798 Mantle fairly slender, about six times as long as broad; fin rhomboid, occupying over half the mantle length; arms short; buccal membrane with 7 tips which bear 2 rows of suckers; shell with curved lateral margins. L. vulgaris Lamarck. A few species, in various seas. Sepioteuthis Blainville, 1824 & Synonym Chondrosepia Ruppell F.S. Leuckart, 1828. Fin occupying nearly the entire length of the mantle; dorsal mantle margin obtusely angled; shell with curved lateral margins; buccal membrane S. in most cases with, occasionally without suckers. A few species, in warmer seas. sepioidea Blainville. Doryteuthis Naef, 1912 Mantle very slender, about eight times as long as broad; fin rhomboid, occupying about half the mantle length; shell broadest near . 1450 and then with the short stalk, straight membrane with suckers on buccal D. plei (Blainville). Few margins, posteriorly pointed; the 7 tips. species, in warm seas. Alloteuthis (Naef) Wulker, 1920 Synonyms Teuthis Gray, 1849, non Linne, 1758; Acroteuthis Berry, 1913, non Stolley, 1911; ? Acruroteuthis Berry, 1920; Acrololigo Grimpe, 1921. Posterior end of the adult animal produced into a 960 point, and is which contains the more or bordered by the ends of the more or less cone-like enrolled tip fins; buccal less long of the shell membrane without distinct and suckers. tips A. media (Linne). 2 European species and one from the Sunda Islands. ? Family LEPIDOTEUTHIDAE Mantle long, with a polygonal segmentation of the integument, posteriorly pointed, with large circular fin not reaching the posterior end; shell with narrow vane which is constricted in the center and forms a long terminal cone; head and anatomy unknown. Lepidoteuthis Joubin, 1895 Characters of the family. L. grimaldii Joubin, in the northern Atlantic Ocean. ? Body fins; Family PROMACHOTEUTHIDAE short, posteriorly rounded, with large, broad, posteriorly united mantle margin free, transversely truncated; shell ?; head small, with each eye; arms fairly long, the ventral ones the shortest, with 2 rows of suckers, tentacles strong, not retractile; buccal a pore anterior to membrane with 7 weak tips, without suckers. Promachoteuthis Hoyle, 1885 Characters of the family. P. megaptera Hoyle, near Japan. 1451 III. Shell STIRPS ARCHITEUTHACEA homy, feather-shaped; (gladius) integument often with light organs; eye cavity open; anterior female gonoducts paired, accessory nidamental glands absent. Buccal membrane in most cases with seldom 8 or 6 and attachments; a hectocotylus tips is in 7, more most cases unknown. 1. Animal fairly Family small; LYCOTEUTHIDAE mantle moderately long, posteriorly pointed, with large triangular fins on the posterior part; eyes large, flatly bulging, with light organs on their ventral side; arms with 2 rows of suckers; tentacles moderately long, with a few luminous organs and with 4 rows of suckers on the club; lower side of the body with luminous organs inside the mantle; buccal membrane with 8 pillars, tips, and attachments; radula with simple points without accessory cusps. Hectocotylus? A. Subfamily Lycoteuthinae Gladius narrow, distinctly concave, constricted behind the center, spoon-shaped at the end; below each eye with 5 light organs with 2 on each tentacle, and with 8 of these in the mantle cavity. Lycoteuthis Pfeffer, 1900 Synonym Thaumatolampas Chun, 1903. Arms not strikingly different in length. L. diadema Chun (Fig. 874), in the Atlantic Ocean. Nematolampas Berry, 1913 Lateroventral arms greatly elongated, thick in the proximal part, with suckers, thread-shaped in the distal part, without suckers, but with several N. light organs. regalis Berry, near the ? Kermadek Islands. Leptodontoteuthis Robson, 1926 Only one head with the arms known. Arms with suckers; buccal 8 pillars; eyes surrounded by light organs; radular plates membrane with with long simple cusps. L. inermis Robson, near South Africa. 1452 f%. # fir f Fig. I 1 874. Lycoteuthis diadema Chun, in ventral view (after B. Subfamily Chun). Lampadioteuthinae Gladius with an obtusely angled vane, which occupies almost two- of its length, without distinct terminal cone; 5 light organs in the mantle cavity, 3 below the eye on either side and one on the eye lid, as thirds well as 5 on each tentacle. Lampadioteuthis Berry, 1916 Characters of the subfamily. L. megaleia Berry, near the Kermadek Islands. 1453 2. Animals ENOPLOTEUTHIDAE Family fairly small; mantle in most cases pointed, with large, nearly or completely terminal fins; gladius feather-shaped with distinctly developed vane, on either side with a ridge-shaped thickening near the margin; rachis groove-shaped, posteriorly with somewhat elevated median cone flatly membranes; protective rib; terminal spoon- to slender cone-shaped; arms in most cases with strong all or most of the suckers are modified into hooks; carpal part of the tentacular club with 2 rows of suckers and adhesive knobs; buccal in membrane with 8 pillars, tips and attachments; light organs most cases present, sometimes below the eyes, sometimes as numerous integument, sometimes inside the mantle small organs in the external cavity; one ventral arm hectocotylized. is A. Subfamily Abraliinae Numerous small organs on the ventral side of the mantle, the light head, and the ventral arms, and a few larger ones on the lower side of eyes; fins extending to the posterior point; tentacular club with one row of hooks; radular plates without accessory cusps. Abralia Gray, 1849 962 Fins triangular, posteriorly narrowed; arms with 2 rows of hooks, the ventral ones with pointed ends, the left one hectocotylized, with moderate membranes and glandular swellings behind protective the tip. Light organs on the mantle closely aggregated, on the eyes 5—7 on either side, the marginal ones more or less large; vane and small terminal cone A few species, in (Fig. gladius with more or less broad 875). various seas. Section Stenabralia Grimpe, 1931. Mantle slender, with fairly small fins; s. s. gladius with narrow vane. A. (S.) renschi Grimpe. Mantle moderately long, with large Gaimard). A. Asteroteuthis Pfeffer, fins. 1909, A. (A.) is — Section Abralia armata (Quoy scarcely & different. veranyi Riippell. Abraliopsis Joubin, 1896 Form similar to that of Abralia with large fins; arms with 2 rows of hooks, the ventral ones produced into 3 knob-shaped swellings, the left one with greatly broadened ventral protective membrane, without glandular swellings; light organs densely aggregated on the ventral side, 5 side on the eyes. on either 1454 Fig. 875. Gladius of Abralia veranyi Ruppell (after Pfeffer). Ocean and Mediterranean A. morisii (Verany), in the Atlantic The names Nepioteuthion and Prodromoteuthis Compsoteuthis and Micrabralia Pfeffer, Pfeffer, is 1912, 1900, were based on juvenile forms; to which genera Enoploion and Asthenoteuthion Pfeffer, belong Sea. 1912, uncertain. Watasenia Ishikawa, 1914 Synonym Watasea Mantle Ishikawa, fairly slender; 1913, non Jordan & Snyder, the fins occupying about half of its 1901. length; mantle with innumerable closely aggregated light organs, 5 small ones ones on the ends of the ventral arms; neck on on the eyes and 3 large either side with 4 longitudinal folds; right ventral arm hectocotylized, with hooks and 2 half-moon-shaped membranes, although without suckers; tentacular clubs with 4 rows of suckers and few large hooks. W. scintillans (Berry), near Japan, B. Subfamily Lower side of the Enoploteuthinae body with many small, more or less distinct light organs arranged in longitudinal bands and one row of 8—10 small organs 1455 below the eyes; not extending completely to the posterior point; fins median radular plates with arm hectocotylized. tentacular clubs with 2 rows of hooks; the 3 points on the outer corners; right ventral Enoploteuthis Orbigny, 1839 Characters of the subfamily. West Africa and one species near Japan. E. leptura (Leach), near C. Subfamily Ancistrochirinae Light organs on the lower side of the mantle large, in small and more regular arrangement, flat number or knob-shaped; tentacular club with 2 rows of hooks. Ancistrochirus Gray, 1849 963 Fins large, extending nearly to the anterior mantle margin, surpassed by the posterior end; light organs in moderate number present on the lower side of the mantle; tentacular clubs with one row of larger and one row of smaller hooks. lesueurii A. (Ferussac & Orbigny), in the Indian and Atlantic Oceans. Thelidioteuthis Pfeffer, 1900 Fins occupying about two-thirds of the mantle length, posteriorly light organs in small number on the mantle, head, stalk; ventral arms shorter than the others; tentacular clubs forming a small point; and tentacular with 2 rows of numerous hooks. T. alessandrinii (Verany), in According pillars warmer seas. to Sasaki, this (?) species has a buccal membrane with 7 and attachments. D. Subfamily Pyroteuthinae Buccal membrane in juveniles free, with 8 pillars, in adult free only in the ventral half, dorsally fused with the protective animals membranes of the arm bases of form a velum; posterior end pointed, surpassing the fins; light organs in the mantle cavity and on the lower side of the eyes. 1456 Pyroteuthis Hoyle, 1904 Synonym Charybditeuthis Vivanti, 1914. Arms with 2 rows of hooks, with suckers on pairs the tips of the 3 upper of arms; on the hand part of the club a small number of suckers of the ventral middle row are modified into hooks; right ventral arm hectocotylized, with a broad glandular lobe on the ventral surface of the distal part, the 2 rows of hooks are developed throughout the length. P. margaritifera (Ruppell). A couple of species in the Mediterranean Sea and Atlantic Ocean. Pterygioteuthis H. Fischer, 1896 A small number of the median suckers on the arms modified hooks; tentacular club beset only with suckers; hectocotylized, without hooks or suckers, membrane and 2 young animals of 3. couple of species, in warmer seas. subfamily. this Family Buccal membrane may A proposed the names Pterygonepion and Ioteuthion for Pfeffer, 1912, organs ventral strong glandular pads opening in the middle of the arm. P. giardi H. Fischer. light into arm with a massive swimming left OCTOPODOTEUTHIDAE free, in most cases with 6 pillars be developed; the tentacles present and attachments; in juveniles are reduced in adult animals. Octopodoteuthis Ruppell, 1844 Synonym Verania Krohn, 1847. Body partly gelatinous; mantle cone-shaped, point; fins large, somewhat rounded; light posteriorly with rounded organs may be developed at the ends of the ventral arms, in one species one pair 964 on the lower side of the head and 2 pairs below the mantle; eyes large; arms somewhat swollen at the ends, with 2 rows of densely placed narrow hooks; gladius with a small flat cone. O. sicula Ruppell, in various seas and a second species near the Bermudas. Taningia Joubin, 1931 Mantle with very large, roundly, triangular fins; arms with 2 rows of suckers with hooks; the dorsolateral arms on the ends with a large 1457 organ; tentacles very small, with 6 rudimentary and 2 light larger suckers; buccal T. danae Joubin, somewhat membrane with 7 pillars. near the Cape Verde Islands. Octopodoteuthopsis Pfeffer, 1912 Fin large, posteriorly leaving a small part of the pointed mantle end free; arms with pointed ends and 2 rows of not very densely placed, short hooks; tentacles absent. megaptera O. doubtful on the east coast of North America. (Verrill), A genus. Cucioteuthis Steenstrup, 1882 Animal pointed, large, fleshy; fins large, as membrane with 6 C. long as the mantle; arms thick, with fairly densely placed strong hooks in 2 rows buccal tips and attachments. molinae (Orbigny). The species to earlier reports in the Pacific is insufficiently known, according Ocean, according to Joubin in the Atlantic Ocean. 4. Body the Family NEOTEUTHIDAE slender, posteriorly pointed; fins occupying about two-thirds of mantle length, moderately broad; arms fairly short, with stalked roundish suckers in 2 rows; tentacular clubs with 4 rows; gladius with pointed terminal cone. Neoteuthis Naef, 1921 Characters of the family. N. thielei Naef, in the southern Atlantic Ocean (known only from juvenile animals). 5. Mantle more or terminal; shaped gladius Family ONYCHOTEUTHIDAE less slender, posteriorly pointed; fins large, triangular, feather-shaped, in the posterior part, with more or less broad vane, roof- with strong median keel, posteriorly flatly spoon-shaped with a solid chitinous or cartilaginous terminal point; funnel cartilage simple, narrow; mantle cartilage longer; neck with a transverse fold and on either side 3 longitudinal folds, often also with 1458 neck membrane folds; buccal in most cases with 7 tips and attachments and 6 pores; arms with 2 rows of small suckers with smooth or weakly denticulate rings; tentacles fairly long, on the carpal part with a roundish group of densely placed small suckers and adhesive knobs; hand part in juveniles with rows of suckers, of which the median ones are later in most cases modified into hooks, whereas the outer ones are reduced or persist as suckers or hooks; a hectocotylus is not known; light organs in most cases absent, occasionally these are developed in the mantle cavity. plates The central and the adjacent plates of the radula have small outer cusps. Cycloteuthis Joubin, 1919 965 Animal fairly small, which does not extend membrane with 7 with long posterior point and large rhombic fin to the point; integument pillars; gladius smooth and weakly broadened the posterior expansion forms a large spoon and ends anteriorly curved point; the end of the rachis strong, at the base of the anterior to thick; buccal in the anterior third; is in flattened; a sharp, tentacles hand part with 5 small suckers and 3 knobs, which with 4 rows of larger, at the end smaller suckers which have a semicircle of denticles; central plate of the radula with outer cusps; between the gills lies a large light organ and on the eyes there seems to be a ring of small yellow luminous organs. C. sirventi Joubin, near Madeira. Joubin wanted to place this genus beside Lycoteuthis; Naef erected the subfamily Lycoteuthinae for it, which he included under the onychoteuthids. Tetronychoteuthis Pfeffer, 1900 Body, fleshy, slender, pointed; integument of young animals with star-shaped minute chitinous warts; fin transversely rhombic, of less than half the mantle length; funnel depression anteriorly roundish; with neck folds; gladius with very narrow vane and narrow, strong; terminal point thread-shaped; flat spoon; median rib arms strong, exteriorly with deep longitudinal furrows; tentacles with scattered carpal suckers; hand part with 4 longitudinal and T. T. many transverse rows of suckers; no light organs. dussumieri (Orbigny), in the Indian Ocean; whether the Atlantic massyae Pfeffer is a separate species seems uncertain. Onychia Lesueur, 1821 (Onykia) Synonyms Steenstrupiola Pfeffer, 1884; Teleoteuthis Verrill, 1885. 1459 Animal fleshy, with smooth, soft, strongly pigmented integument, moderately slender, with short point; fins of less than half the body length; without folds; funnel depression anteriorly roundish; gladius with short and broadly lanceolate vane; the chitinous terminal rachis free point lies obliquely on the spoon; carpal group of the tentacles only on webbed by a membranous the sides fold; hand part in the adults with 2 rows of hooks and 2 marginal rows of suckers, some of which are occasionally O. lost. caribaea Lesueur. Few species, in various seas. Onychoteuthis Lichtenstein, 1818 Synonym Animal Teleonychoteuthis Pfeffer, fleshy, with with long posterior point; soft, 1900. strongly pigmented integument, fin large, transversely slender, rhombic, with produced posterior point, in the adult animal longer than half the mantle length; with neck folds; funnel depression anteriorly pointed; cartilaginous ridge of the mantle at least twice as long as the funnel cartilage; gladius with moderately long free rachis and in the median third with lanceolate vane which is narrowed posteriorly and greatly the short, part forms a high, sharp keel, the chitinous terminal point part in the adults with 2 mantle cavity inflected lie downward, whereby on the posterior rib which becomes lower toward the spoon; is slender triangular, carpal group of the tentacles surrounded 966 is spoon appears separated; the median flat obliquely attached; by a membranous web; hand rows of hooks, without marginal rows; in the 2 light organs, the anterior one on the liver capsule, the posterior larger one on the ink sac. A nearly single species O. banksii (Leach) (Fig. 876), distributed throughout all seas. Chaunteuthis Appellof, 1880 Body gelatinous-cartilaginous, flaccid, with very strongly soft, pigmented integument, slender, with long posterior point; fin large, transversely rhombic, with only slightly produced posterior point, longer than half the mantle length; neck with folds; funnel depression anteriorly pointed; cartilaginous ridge of the mantle twice as long as the funnel cartilage; gladius similar to that in Onychoteuthis, although the present only in the posterior half and the terminal point short; tentacles C. were torn off; no is vane shorter; is arms light organs. mollis Appellof, in the Mediterranean Sea and Atlantic Ocean. 1460 Fig. 876 Onychoteuthis banksii (Leach) in ventral view (after Pfeffer). Ancistroteuthis Gray, 1849 Body fleshy, with soft, smooth integument, slender with very long point; fin rhombic, with long drawn-out posterior point, longer than half the mantle length; neck with folds; funnel depression anteriorly pointed; gladius only with narrow vane in the posterior third; spoon narrow and fairly deep with long and slender chitinous terminal point; carpal group of the tentacles surrounded by a membranous web; hand part with 2 rows of hooks, without marginal rows; no light organs. A. lichtensteinii (Ferussac & Orbigny), in the Mediterranean Sea. Moroteuthis Verrill, 1881 Animal large, fleshy, with long posterior point, sometimes with tubercles of the lower integument, without distinct neck folds; flat funnel 1461 depression anteriorly roundish; gladius with broad lanceolate vane occupying nearly the entire length, posteriorly passing into the spoon, which nears a large, slender, cartilaginous terminal cone; carpal group of the tentacles surrounded by a membranous web; hand of hooks, without marginal suckers; no Subgenus Moroteuthis s. part with 2 rows light organs. Gladius without dorsal median furrow; s. terminal cone with roundish cross-section. M. (A/.) robusta (Verrill). 2 species in the northern Pacific Ocean. Subgenus Moroteuthopsis Pfeffer, furrow, posteriorly roof-shaped; 1908. Gladius with dorsal median terminal cone with triangular cross- M. (M.) ingens (Edg. Smith), near Patagonia. According to Grimpe, M. aequatorialis Thiele, from the equatorial part of the Atlantic section. Ocean, perhaps does not belong here. ? Animal large lips Mesonychoteuthis Robson, 1925 (insufficiently known); gladius? Mouth without lobes; with long thorns; arms with 4-9 pairs of large hooks between 2 rows of suckers at the end of the proximal quarter, their terminal quarter naked and greatly thinned; tentacles small, on the hand part only with hooks which can be rotated; shaft with a dense row of suckers and knobs besides the carpal ones; central plate and its adjacent plates with outer cusps. M. hamiltoni Robson, near the South Shetland 6. GONATIDAE Family Body medium-sized; mantle terminal rhombic or roundish Islands. fairly slender, posteriorly fin; pointed with gladius with relatively large pointed terminal cone, which does not extend to the posterior end of the mantle; neck with annular and 3 longitudinal folds; funnel cartilage narrow, with simple longitudinal groove; mantle cartilage thread-shaped; buccal membrane with 7 attachments; arms with 4 rows of suckers, of which the two inner rows on the 1st to 3rd pairs of arms in older animals are transformed into hooks; also on the hand part of the tentacles a few suckers may be modified into hooks; no light organs. Hectocotylus development does not seem the adjacent plate (which is to take place. Central plate reduced in Gonatus s. s.) of the radula and with outer cusps. Gonatus Gray, 1849 Synonyms Lestoteuthis + Cheloteuthis Tentacles are developed. Verrill, 1881. 1462 Subgenus Berryiteuthis Naef, 1921 {Berryteuthis) (synonym M. Ishikawa, 1924). Tentacular club also in older animals Pfefferiopsis beset only with suckers; radula with 7 longitudinal rows of plates. G. (B.) magister Berry, in the northern Pacific Ocean. Subgenus Gonatus s. s. Proximal part of the tentacular club broadened; row of in addition to suckers with a longitudinal variably-sized hooks; radula with 5 longitudinal rows of plates. G. (G.) fabricii (Lichtenstein), distributed in northern and southern seas. Gonatopsis Sasaki, 1920 Tentacles are reduced; 1st to 3rd arms with 2 rows of hooks and marginal suckers, the ends thin, with 10 or more rows of long-stalked suckers; radular rows with 7 plates. G. octopedata Sasaki. 2 species, in the northern Pacific Ocean. 7. Body fins Family PSYCHROTEUTHIDAE fairly large, elongate, posteriorly pointed, with large triangular which do not completely reach the posterior end; gladius long, feather-shaped, keeled; vane fairly large, not reaching the anterior end, posteriorly gradually narrowed and forming a small pocket at the end, without solid terminal cone, not extending to the posterior end of the mantle; buccal membrane with 7 pillars, tips, and attachments; dorsal and ventral interlocking cartilages strong, moderately long, with 2 pair with darkly colored 968 shows strong, large, with flat furrows; arms fairly rows of smooth-ringed suckers, the 3rd membranous webs at the end, whose inner side several alternately placed transverse bulges; tentacles long, with slightly broadened club which bears 4 longitudinal rows of row of suckers with denticulate chitinous rings; behind the club with a small suckers and adhesive knobs; hectocotylus?; radular plates without outer cusps. No light organs. Psychroteuthis Thiele, 1920 Characters of the family. P. glacialis Thiele, in the Antarctic 8. Animals Family Ocean. ARCHITEUTHIDAE gigantic; mantle slender, posteriorly pointed, with terminal, elongated oval, posteriorly pointed fin; gladius posteriorly pointed; vane 1463 flat in the anterior part, in the posterior part inrolled into a small terminal cone, in most cases with 2 stronger ribs diverging anteriorly from the posterior end of the rachis and several weaker ribs, ending far anterior to the posterior folds; funnel end of the mantle; neck with transverse and longitudinal and mantle cartilages longish, simple; arms long and strong, with 2 rows of suckers with denticulated rings; tentacles very long; club with 4 rows of suckers with denticulated rings; shaft with longitudinal rows of small suckers and adhesive knobs; buccal membrane with 7 tips central plate of the radula and adjacent and attachments; hectocotylus?; teeth with outer cusps. Architeuthus Steenstrup, 1857 Synonyms Megaloteuthis Kent, 1874; Dinoteuthis More, 1875; Mouchezia Velain, 1877; Megateuthis Hilgendorf, 1880; Plectoteuthis Owen, 1881; Steenstrupia Kirk, 1882 (non Forbes, 1846); ? Dubioteuthis 1900. Joubin, Characters of the family. dux Steenstrup. A. It giant squids belong in the 9. Mantle small in is not established whether still all described same genus. Family HISTIOTEUTHIDAE comparison to the head with the arms, short cone- shaped, posteriorly more or less pointed, with rounded fins of moderate size attached on the dorsum; left eye more or less enlarged; numerous organs mainly on the lower side of the mantle, the head, and the light arms; neck without folds and funnel depression; funnel cartilage moderately broad, with a longitudinal furrow; mantle cartilage short, ridge-shaped; gladius feather-shaped, without terminal cone; arms with 2 rows of suckers, the stalks of which are laterally attached, in Histioteuthis with a large velum; tentacles long, club in most cases with 4-7 rows of shaft with one row of suckers and adhesive knobs; buccal most cases with 7 pillars, points, and attachments; as a rule both dorsal arms are hectocotylized. suckers, on the membrane in Stigmatoteuthis Pfeffer, 1900 Mantle pointed or somewhat rounded with terminal, posteriorly indented fin; light organs not very numerous, on the ventral arms in 3 longitudinal rows, on the remaining arms in one ventral 969 of smaller organs on the dorsal side; arms without row and one row distinct web; the 1464 suckers on the arms and tentacles with denticulate horny rings; radular plates without lateral cusps. S. hoylei (Goodrich). A few species, some of which are doubtful, mainly in the Indian and Pacific Oceans, probably also in the Atlantic Ocean. Calliteuthis Verrill, Animal similar light 1880 to Stigmatoteuthis; fin posteriorly distinctly indented; organs not very numerous, on the arms as in the preceding genus; by a narrow velum; the larger suckers on the arms with smooth, the smaller ones with denticulate, horny rings, the 3 upper pairs of arms joined those on the tentacles with accessory thickenings. C. meneghinii (Verany), in the Mediterranean Sea and the neighboring Ocean. Atlantic Meleagroteuthis Pfeffer, 1900 Light organs on the ventral side of the mantle and head, as well as on the ventral arms very densely placed, on the remaining arms in 1—5 rows; fin terminal; posteriorly indented; the 3 upper pairs of arms have a narrow velar tentacles are membrane the base; at on the arms and the suckers denticulate. M. hoylei Pfeffer on the west coast of Central America, one species Cape Verde (asteroessa Chun) near the Islands, and one {separata Sasaki) near Japan. Histioteuthis Orbigny, 1839 Fin roundish, posteriorly somewhat indented; light organs on the lower side of the mantle and head not very densely placed; ventral arms with 3 longitudinal rows, the remaining arms with one dorsal row of large and one ventral also lie row of small ventrally at the base light organs, of the 3rd pair; although large organs buccal membrane in juveniles with seven parts, in older ones with 6 parts; the 3 dorsal pairs of arms are joined together by a broad velum; whereas the ventral pair is connected with the velum by tentacles remain free; suckers its ventral protective on the arms and membranes and the tentacles with denticulate rings. H. bonelliana (Ferussac) (Fig. 877), mainly in the Mediterranean Sea and Atlantic Ocean, although also Hoyle, 1885 (atlantica Hoyle) is in the Indian a juvenile form. Ocean. Histiopsis 1465 Fig. 877. Histioteuthis bonelliana (Ferussac), in ventral view (about 1/6 nat. size) (after Pfeffer). 970 Histiochromius Pfeffer, 1912 ? The genus Brachioteuthis; based on a young animal described by Chun as mantle calyx-shaped, distinctly longer than broad, is posteriorly rounded, with terminal fin; head with large (different?) eyes; club of the tentacles with light many suckers in several (up to 9) rows; without organs. H. chuni Pfeffer, in the Indian Ocean. 10. Family Animal small; mantle ALLUROTEUTHIDAE fairly long, cylindrical, posteriorly papilla-shaped tip below the thin fin, which is with short posteriorly deeply indented and far surpasses the end of the body; head broader than the mantle, with large eyes; gladius anteriorly with narrow, free rachis; vane broad and hole at thin, its posterior end the end; buccal downwardly membrane with inflected and forming a 7 parts; funnel cartilage longish, 1466 simple; arms fairly strong, with 2 rows of suckers with distally denticulate chitinous rings, the ventral arms with smaller suckers and near this with one row of small light organs, also with swimming membranes; tentacles short and thin, on the shaft with 2 rows of small suckers, on the carpal part with a quantity of very small suckers and on the club with 2 rows of large ones and oh either side with one row of small suckers; radular plates without accessory cusps. Alluroteuthis N. Odhner, 1923 Characters of the family. A. antarctica N. Odhner, in the Antarctic Sea. Based on the Odhner considers it possible by me in 1921 under the name structure of the radula, the juvenile form described that Parateuthis tunicata belongs to Alluroteuthis. 11. Family Animal small; mantle BATHYTEUTHIDAE fairly short, with separated fins; gladius with broad, posteriorly roundish vane on the posterior half; eyes large; neck without distinct funnel folds; cartilage simple, with narrow groove; mantle cartilage longer, thread-shaped; arms short, with 2-4 rows of very small suckers; tentacular club with very numerous and small suckers. Bathyteuthis Hoyle, 1885 Synonym Benthoteuthis Verrill, 1885. Fin small, attached just before the posterior end of the mantle, with continuous musculature; head with enormously bulging eyes; arms attached externally far upward, the 3 upper pairs with strong supports of the protective membranes; ventral arms dorsally attached; the 3 upper pairs of arms each have a light organ on the basal part of their outer surface. B. abyssicola Hoyle, in various seas. Robson, 1921, described a small animal from the Indian Ocean, with a sack-shaped mantle, large eyes, and long thin tentacles, under the name Chunoteuthis minima, and placed it in this family; Grimpe in 1922 changed the genus name to Indoteuthis doubt as a young Bathyteuthis. and considered the animal with 1467 Ctenopteryx Appellof, 1889 971 Mantle dorsally flattened, with laterally attached fins, which in young animals occupy only the posterior part, in older animals the entire length, and are supported by comb-shaped muscle bundles; eyes only slightly bulging, laterally directed; membranes without arms externally not attached; protective supports; ventral arms ventrally attached; no light organs. sicula (Verany), in the Mediterranean Sea and the neighboring C. Ocean. Atlantic 12. BRACHIOTEUTHIDAE Family Mantle slender, posteriorly sharply pointed, with fin; fairly large terminal gladius with short vane, which posteriorly forms a pointed terminal cone; light organs seem to be absent; eyes large; neck folds weak; funnel cartilage simple, with broad depression and narrow margins; longish, mantle cartilage longer, ridge-shaped; buccal membrane with 7 supports, and attachments; arms with 2 sucker rows and with swimming points, and protective membranes, the 2 others; rings of the suckers pairs lateral in the distal much stronger than the half with broad, blunt teeth; tentacles strong, fairly long; club in distal half with 5 or 6 rows of larger suckers with pointed teeth, in the proximal half with very numerous and small suckers; an attachment apparatus absent. Brachioteuthis Verrill, 1881 Synonyms Tracheloteuthis Entomopsis Rochebrune, 1 Steenstrup, 1882; Verrilliola Pfeffer, 1884; 884. Characters of the family. B. beanii Verrill. Atlantic Few some of which species, are doubtful, in the Ocean. 13. VALBYTEUTHIDAE Family Mantle elongated calyx-shaped, posteriorly very pointed, with large roundish, nearly terminal funnel large, fin; interiorally with head with 3 large, obliquely directed eyes; strong glandular bulges; cartilaginous cusps elongated oval; no light organs; arms weak, the dorsal pair the shortest, with small suckers, the variably-sized suckers, the two ventral lateral pairs largely pair soft, colorless, with 2 rows of almost without musculature, on the proximal part with a row of 12 suckers becoming 1468 gradually smaller; tentacles in the basal part with a pointed, proximally directed process, from which a brown chitinous longitudinal strip extends weakly broadened club bears 4 rows of small, scarcely stalked suckers with large, dark, smooth rings, whereas the suckers on the arms are spherical, stalked, and furnished with denticulate rings. to the club, the Valbyteuthis Joubin, 1931 Characters of the family. V. danae Joubin, 14. in the Family Gulf of Panama. OMMATOSTREPHIDAE Mantle long and slender, posteriorly pointed, with large, most in cases triangular fins; gladius very thin; vane rudimentary, only at the posterior end forming a short cone; funnel depression in most cases with a system of folds which are longitudinally directed in the anterior part, 972 this part (foveola) posteriorly delimited is may be transverse fold and there cartilage triangular; the furrow posteriorly the posterior transverse broadened and separated from furrow by a pair of strong tubercles; mantle cartilage T-shaped; eyes not projecting; membrane with by a half-moon-shaped additional folds in the corners; funnel neck with strong ring-shaped space, joined with the tentacles by a arms folds; buccal 7 points, in most cases separated from the arms fairly strong, with 2 membranous rows of suckers; tentacular club by a bridge; in the center with larger, in the terminal part with smaller suckers, on the carpal part in most cases with an attachment apparatus consisting of suckers and knobs; one ventral arm or both hectocotylized; the 3 median radular with outer cusps (Fig. 878); in young animals {Rhynchoteuthis Chun, 1903, non Orbigny, 1847 = Rhynchoteuthion Pfeffer, 1908) the tentacles are fused together to form a hollow proboscis; light organs plates Hyaloteuthis and one Ommatostrephes and one developed only in Symplectoteuthis species. Fig. 878. A half radular row of Illex coindeti (after Naef). (Verany) 1469 A. Subfamily Illicinae Folds in the funnel depression indistinct; furrow of the funnel and longitudinal ridge of the mantle cartilage cartilage straight; an open pore between the buccal membrane and the attachment of the 2nd arms; attachment apparatus of the tentacles indistinctly developed; gladius weak, brownish yellow. Illex Steenstrup, of the tentacular club with 8 rows of suckers; large rings Distal part of the distally with crenellated teeth, proximally with a high arms lateral 1880 d the suckers are enlarged; right or left ventral arm hectocotylized; the large median suckers of the tentacular club with rings ridge, in the having entire margins or ringed with crenelle-like incisions. /. illecebrosus (Lesueur), in the Ocean. Pfeffer does not consider /. Mediterranean Sea and Atlantic coindeti (Verany) as a separate species. Todaropsis Girard, 1890 Distal part of the tentacular club with of the lateral arms with pointed teeth 4 rows of suckers; large rings distally, proximally with a low major ridge; both ventral arms hectocotylized; the large median suckers of the tentacular club ringed with pointed teeth which are separated from one another. T. eblanae (Ball), in the B. Mediterranean Sea and Atlantic Ocean. Subfamily Ommatostrephinae Funnel depression with foveola, half-moon-shaped pocket, and longitudinal thin folds, without lateral pockets; membrane joined with cartilage similar to that in 2nd arms by a membrane, without pore; attachment apparatus of the tentaacles Illicinae; buccal the base of the incomplete, with denticulate small suckers; large suckers of the club without cross-teeth. Nototodarus Pfeffer, 1912 973 Large suckers of the distally, N. lateral arms with pointed triangular teeth high edge of the proximal side with few broad crenellated teeth. insignis (Gould), near New Zealand. 1470 Ommatostrephes Orbigny, 1839 (Ommastrephes) Synonyms Todarodes Mabille, Large suckers of the distally, large Steenstrup, 1880; Martialia Rochebrune & 1889. arms with slender cone-shaped teeth lateral proximally with smooth margin which is outwardly reflected; suckers on the median part of the tentacular club ringed with slender teeth separated from one another, between which low crenellated teeth may be present. O. sagittatus (Lamarck). Few species, in the Atlantic and Pacific Oceans. Okada, Sasaki, 1927, erected the genus which has an elliptical light Ornithoteuthis for O. organ on the rectum; volatilis it may be considered as a subgenus or section of Ommatostrephes. C. Subfamily Sthenoteuthinae Funnel depression also with lateral pockets; buccal membrane as in Ommatostrephinae; depression of the funnel cartilage anteriorly buckled; rings of the largest suckers on the lateral arms denticulated all-around, the farther distally-situated suckers smooth on the proximal side, outwardly reflected; large suckers of the tentacular club with 4 larger teeth arranged attachment apparatus well developed, with smooth-ringed crosswise; suckers and knobs; right ventral arm hectocotylized. Hyaloteuthis Gray, 1849 On light the ventral side of the mantle are 19 regularly arranged, roundish organs situated in pits and one pair on the lower side of the head; funnel and mantle cartilages not fused with one another, similar to those in Illicinae, below the 2nd arms with 1 or 2 considerably enlarged suckers center; the rings of the arm suckers with somewhat and alternately large small teeth on the distal side; rings of the largest tentacular suckers smooth, a few smaller suckers with unequal teeth; carpal part with a single adhesive knob. H. pelagica (Bosc), in the Atlantic and Pacific Oceans. Sthenoteuthis Verrill, 1880 Locking cartilages of the funnel and mantle not fused with one another; arms not elongated whip-shaped, with about 50 pairs of suckers; 1471 ventral protective membrane of the 3rd pair of arms very broad; supports of the protective membranes not free lobe- or palp-shaped. pteropus (Steenstrup) = megaptera S. Atlantic Ocean and Mediterranean (Verrill). Few species, in the Sea. Dosidicus Steenstrup, 1857 Animal very large. Locking cartilages not fused with one another; ends of the arms elongated whip-shaped, with over 200 pairs of small suckers; ventral protective membrane of the 3rd pair of arms about as broad as the arm; supports of the remaining protective membranes proximal half in most cases produced into 974 free, lobe- in the or palp-shaped tips. D. eschrichti Steenstrup, probably gigas (Orbigny), in the southern Ocean. Pacific Symplectoteuthis Pfeffer, 1900 Locking cartilages of the funnel and mantle firmly fused with one another at the boundary of the longitudinal and transverse furrow; arms not elongated whip-shaped; ventral protective as broad as the arm; left ventral tentacles with membrane of arm hectocotylized; the 3rd arms carpal part of the 2-4 adhesive knobs. S. oualaniensis (Lesson). 2 species, in the Pacific and Indian Oceans. S. luminosa Sasaki has pale bands on the lower side of the mantle, the head, and the ventral arms, which Okada considered as light organs without pigment; Berry, 1916, erected the genus Eucleoteuthis for this species. 15. Family THYSANOTEUTHIDAE Mantle long and moderately broad, with long obtusely angled anterior to the center; lateral fins which are gladius posteriorly pointed, without terminal cone; vane anteriorly gradually broadened and anteriorly produced wing-shaped; free rachis short; funnel depression without folds; neck with transverse and longitudinal folds; buccal membrane with 7 points; longitudinal furrow of the funnel cartilage in the center strongly broadened unilaterally; mantle cartilage with a thick transverse ridge; arms with broad protective membranes having thread-shaped muscular supports and with 2 rows of small denticulate suckers; left ventral arm hectocotylized; tentacular club with 4 sucker rows, behind which there are 2 rows of alternating suckers and knobs; no light organs. — 1472 Thysanoteuthis Troschel, 1857 Characters of the family. T. rhombus Troschel, in the Ocean. According to Sasaki, Mediterranean Sea and northern Pacific T. nuchalis Pfeffer not different from is rhombus. ? Cirrobrachium Hoyle, 1904 From one animal only the head with the arms is known; these have smooth-margined suckers in 2 rows and more or less long threads, which probably represent muscular supports of protective membranes. C. filiferum Hoyle, in the equatorial Pacific Ocean. 16. Family CHIROTEUTHIDAE Mantle slender calyx-shaped, posteriorly more or elongated and sometimes far surpassing the roundish vane weak, forming a long terminal cone; light fin; less greatly gladius narrow; organs are often developed; eyes large, more or less projecting; an olfactory tubercle present on either side; neck without folds; funnel cartilage oval or earshaped, sometimes with 1 or 2 strong tubercles; mantle cartilage nose- shaped; arms fairly long, with 2 sucker rows, the ventral pair the largest; tentacles long, without attachment organ, luminous glandular knobs; club with 4, on the outer side with a few 8, or many sucker rows. A. Subfamily Chiroteuthinae Tentacular club with 4-8 sucker rows; light organs on the eyes, on the ink sack, and in one row on the ventral arms. Chiroteuthis Orbigny, 1839 975 Characters of the family. Pfeffer has recognized a number of groups them known only from juvenile forms, whose as subgenera, some of relationships to mature forms are uncertain. Doratopsis Rochebrune, 1884 (synonyms Hyaloteuthis Pfeffer, 1884, non Gray, 1849; Toroteuthis Tomlin, 1931). Eyes circular, without ventral process; tentacular club with a proximal part with small suckers increasingly differentiated from a distal part with larger rings. C. (D.) vermicularis (Riippell). Planctoteuthis Pfeffer, 1912. Eyes in most —— 1473 cases oval, with a ventral process; suckers of the tentacular club not 976 distinctly C. different. exophthalmica (Chun). (P.) Tankaia Sasaki, 1929. Mantle posteriorly with thread-shaped process, attached to which is kidney-shaped anterior part of fin; process; tentacular club with many body long; eyes roundish, without (about 150) small suckers in several rows. C. (T.) borealis Sasaki, near Japan. ? Diaphanoteuthis Tomlin, 1931 (synonym Leptoteuthis Verrill, 1884, non H.V. Meyer, 1834). Fin leaf-shaped, longer than broad; anterior part of body half mantle; tentacular club with about 4 rows of small diaphana (Verrill), the northern in Ocean. Atlantic as long as the suckers. C. (D.) Chiridioteuthis Pfeffer,1912. Mantle posteriorly stalk-shaped with oval fin; rings of the arm suckers low distally with high, proximally with tentacular club teeth; suckers of the with thin stalks, distally with high teeth, proximally smooth. C. (C.) pellucida Goodrich, in the Indian Ocean. Subgenus Chiroteuthis s. s. Mantle end posteriorly thin, without spindle-shaped swelling; ventral arms very large; stalks of the suckers of the tentacular club with a broad basal pillar, the latter at the end with a thickened or fluted suckers on each knob from which a club; proximally smooth. C. arm suckers (C.) about 100 thin stalk arises; distally with crenellated teeth, veranyi (Ferussac) (Fig. 879), in the Mediterranean Sea and Atlantic Ocean. Subgenus Chirothauma Chun, 1910. Mantle end posteriorly swollen spindle-shaped, with a narrow membrane which is not continuous with the roundish fin; stalks of the tentacular suckers at the base somewhat thickened or with a triangular process in the center; about 300 suckers on each club; arm suckers similar to those in Chiroteuthis s. s. or distally with pointed, proximally with blunt teeth. C. (C.) imperator Chun. species, in the Pacific ? Arms and Few and Indian Oceans. Chirosoma Joubin, 1912 tentacles with 4 rows of small suckers. So ciently described. According to Joubin, it far insuffi- has to be placed in a separate subfamily. C. regnardi Joubin, in the Atlantic deep sea (4000 m). ? Chiroteuthoides Berry, 1920 Mantle posteriorly produced thread-shaped, with posteriorly dented fin, in- probably also with a posterior membrane; arms with 2 sucker rows, the ventral ones the largest, the third very short; tentacular club unknown; no light organs. C. hastula Berry, in the northern Atlantic Ocean. 1474 Fig. 879. Chiroteuthis veranyi (Ferussac), in dorsal view (after Pfeffer). 1 1475 B. Subfamily Mastigoteuthinae Tentacular club with numerous sucker rows; distinctly developed light organs absent. Mastigoteuthis Verrill, Synonyms Chiroteuthopsis Iridioteuthis Sasaki, Mantle more or rhombic fin; Pfeffer, 1 88 1900; Idioteuthis Sasaki, 1916 elongated pointed, with large roundish or less head broad; eyes large, indented; anteriorly tubercles short-stalked; tentacular suckers small, in M. agassizii Pacific = 1929. Verrill. A few species, in olfactory 10-30 rows. the northern Atlantic and Oceans. Grimpe, 1922, erected a subgenus Mastigopsis for M. hjorti Chun. 977 ? Mantle very slender Valdemaria Joubin, 1931 posteriorly pointed cylindrical, into a long thread; the roundish fin attached at the and produced end of the mantle and the beginning of the thread; head narrow, with roundish projecting eyes; arms long, the ventral ones the shortest, the 2nd the on the small, long-stalked, distally with pointed teeth, 1—2 rows, on the 3rd arms in tentacles thin; club with several V. danae Joubin, longest; ventral suckers arms in 6, on the remaining ones in 4 rows; (6-8) rows of very small suckers. in the northern Atlantic Ocean. C. Subfamily Grimalditeuthinae Mantle slender, posteriorly greatly produced, with a branous web posterior to the transversely oval of the fin steeply arched roof-like, fin; fin-like mem- gladius in the region with a narrow, unclosed terminal cone; funnel very large, without locking cartilage, but fused with the mantle; neck without folds; arms fairly large, with 2 sucker rows; the ventral arms small; tentacles reduced. Grimalditeuthis Joubin, 1898 Characters of the subfamily. G. bonplandi (Verany), in the northern Atlantic Ocean. According to Grimpe, Enoptroteuthis Berry, 1920 (spinicauda Berry), 1476 is perhaps a juvenile form of Grimalditeuthis; the eyes are stalked, the mouth part elongated; tentacles with a small club which bears few is suckers in 2 rows. Family JOUBINITEUTfflDAE 17. Mantle broader than the head, at the end with a roundish fin; without organs; head fairly long and narrow; arms thin, with very small light stalked suckers, which in the center of the arms are arranged in 6 rows; the ventral arms are about as long as the mantle, the others considerably longer, up to four times as long. Joubiniteuthis Berry, 1920 Characters of the family. J. portieri (Joubin), in the northern Atlantic Ocean. 18. Family CRANCHIIDAE Mantle dorsally fused with the dorsum and ventrally with the funnel in bands; the musculus depressor infundibuli expands into a thin 3 which approaches the sides of the mantle and the ventral margin lamella, of the musculus collaris and divides the mantle cavity into 3 chambers; mantle in most cases transparent, gelatinous or membranous, slender or swollen, often produced into a pointed tip; fins short and roundish or long and narrow; the gladius anteriorly forms a small plate, posteriorly a lanceola, which either directed is straight posteriorly or ventrally; eyes sessile or stalked, with light organs the eye ball; funnel large, without valve; buccal and attachments; arms suckers; one ventral in arm is curved on the ventral side of membrane with 7 pillars most cases short and weak, with 2 rows of hectocotylized; tentacles in with weak club, sometimes reduced; some of most cases the strong, suckers only in Galiteuthis modified into hooks. A. Subfamily Cranchiinae 978 A row of light organs on the ventral margin of the eye ball, sometimes a few also close to the pupillary margin; mantle beset with star-shaped tubercles or proceeding from the points of fusion, with one or more cartilaginous ridges with a row of small warts. 1477 Leachia Lesueur, 1821 Synonyms Perothis Rathke, 1833; Dyctydiopsis Rochebrune, 1884. Mantle ventrally on either side with a cartilaginous ridge with small star-shaped warts; fins terminal; anterior and posterior half of the lanceola slender and produced into a greatly pointed axis; eyes large, projecting vesicle-like; row the ventral or more L. tip, head short and with straight thick, between of light organs and the pupillary margin also with one light organs; tentacles torn off. Few cyclura Lesueur. species, in various seas. Pyrgopsis Rochebrune, 1884 Synonyms Zygaenopsis Rochebrune, 1884, non Felder, 1874; Zygocranchia Hoyle, 1909; Euzygaena Chun, 1910. Eyes small, long-stalked; head long and slender, with only one row of light organs beside the ridge-shaped margin of the eye median suckers of the tentacular club larger than the marginal ventral ball; suckers, their rings ringed with pointed denticles; the other characters as in — Leachia P. perhaps a juvenile form. rhynchophora Rochebrune, probably = zygaena (Verany). Few species, in various seas. Drechselia Joubin, 1931 Mantle slender cone-shaped, posteriorly gradually pointed, 2 orly with ventral ridges, cartilaginous versely oval fin; funnel in 9 posteriorly larger than in with anteri- large trans- d\ internally with a strong gland; head short and thick; eyes large, externally flattened, lens mucous and margin projecting, on the bulging lower side with a group of 6 light organs, on the margin and between it and the lens with another group of 6 organs, in addition another row of very small yellow organs lying above the lens; gladius narrow, strong, anteriorly and posteriorly only slightly broadened; terminal 3rd pair in the 9 cone very long and pointed; arms strong, the considerably longer than the dorsal and ventral ones, with 2 rows of roundish short-stalked suckers, whose horny rings distally have 3 teeth, the central 2; in the d of which the right ventral arm in the is twisted expansion; tentacles in the thereafter thin, thickening; in the 9 as 9 is much hectocotylized, c? larger than the other it forms a peculiarly distinctly thickened at the base, broad as the arms without proximal club narrow, with a few shallow pits, although suckers. D. danae Joubin, in the Pacific Ocean near Panama. without 1478 Liocranchia Pfeffer, 1884 Mantle with small fins which freely surpass the posterior end of lanceola, anterior half of the lanceola long and pointed, posterior half greatly shortened; the dorsal axis of the mantle continues into the median axis of the fin, whereas the posterior end of the mantle and g. t iius curved ventrally; head short and thick, eyes spherical, sessile, is with 4 equally-large light organs; mantle with 4 ventral cartilaginous ridges. L. reinhardti (Steenstrup). Few species, in various seas. Cranchia Leach, 1817 979 Mantle and dorsal surface of the tubercles; eyes with fins with densely placed star-shaped 12 light organs below the pupil and 2 above otherwise similar to Liocranchia. C. scabra Leach Fig. 880. (Fig. 880), in various seas. Cranchia scabra Leach, (after Chun). in dorsal view it; 1479 Liguriella Issel, 1908 Mantle with a dorsal row of sawtooth-shaped tubercles on a ridge, although without ventral cartilaginous ridges; rhombic lanceola short with greatly shortened anterior and posterior halves; the mantle posterior to the end of the lanceola continues considerably toward the posterior form of an obtuse bulge, so that the small fins are separated in from one another, attaching infraterminally; cephalic pillars distinct; eyes stalked. podophthalma L. Issel, in the northern Atlantic Ocean. B. Subfamily Taoniinae On the ventral side of the eye ball with only one round or moon-shaped light 1 half- organs concentrically embracing each other; mantle without cartilaginous ridges, which at the most may be indicated at the points of fusion; anterior and posterior halves of the lanceola slender and pointed in mature animals; dorsal axis of the mantle coinciding with that of the visceral sack and of the fin. Phasmatopsis Rochebrune, 1884 Mantle membranous, slender, cone-shaped, gradually narrowing into a long, sharp terminal, tip; fin long, broadly lanceolate with greatly elongate point, attached completely at the sides of the mantle; gladius as long as the stalks; larger rings fin; head broad; eyes on vane of the thick, short barrel-shaped of the arm suckers with crenellated teeth; tentacles torn off. P. cymoctopus Rochebrune, in the Atlantic Ocean near Madeira. Toyeuma Chun, 1906 Fins long and narrow, anteriorly considerably surpassing the greatest width of the lanceola, posteriorly not reaching the needle-shaped pointed tip; head long and slender; eyes cone-shaped with broad, moderately long stalks; arms small; tentacles with swimming membrane and narrow club; suckers differing only slightly. T. belone Chun, in the Indian Ocean (probably a juvenile stage). Anomalocranchia Robson, 1924 Mantle muscular, without fins and cartilaginous ridges; the gladius only slightly surpassing the posterior end; eyes large, on short, thick 1480 stalks; arm suckers toothless, some of those on some smooth; funnel very large. A. the tentacles denticulate, impennis Robson, near South Africa. Taonius Steenstrup, 1861 980 Synonym Desmoteuthis Verrill, 1881. Body gelatinous, strongly colored, with a tail thread; fin anteriorly extending beyond the greatest breadth of the lanceola; head short and thick, with very large, nearly spherical, bulging eyes; funnel fairly large; gladius with narrow rachis and broad, lanceolate vane, half is inrolled whose and forms a long, slender terminal cone; arms most cases weakly denticulate suckers; tentacles pavo (Lesueur), in the Atlantic and Pacific Oceans. variably-sized, in T. posterior short, with Verrilliteuthis Berry, torn off. 1916 Mantle membranous, spindle-shaped, very gradually narrowed pos- on the lateral edges of the mantle; lanceola and posteriorly elongated pointed, very broad; eyes very large, teriorly; fins long, attached anteriorly nearly spherical, unstalked; suckers on the distal half of the two lateral pairs of arms especially smooth or somewhat incised rings; 4 rows of suckers, whose carpal part and distal half of the shaft large, with tentacles with thick shaft and distinct club, with rings all around have pointed teeth; with small denticulate suckers and knobs. V. hyperborea (Steenstrup), in the northwestern Atlantic Ocean. Megalocranchia Pfeffer, Mantle calyx-shaped, posteriorly thinning 1884 fairly rapidly and forming a narrow, pointed cone; fin fairly large, oval, terminal, attached on the dorsum; lanceola posteriorly slender, anteriorly with a very short rhombic expansion; eyes very large, unstalked; arms with very strong protective membranes supported by rings of which have blunt distinct protective cross bridges and 2 rows of suckers, the teeth; tentacles moderately strong; club with membranes and a swimming membrane and with 4 rows of suckers, the rings of which have pointed denticles, proximally they merge into 2 rows of small suckers. M. maxima Pfeffer. Few species, in various seas. Leucocranchia Joubin, 1912 Body large, with strong tubercles with a very large light organ. between the fins; below each eye 1481 pfefferi L. Joubin, in the deep sea (4000 m). So Atlantic far described. insufficiently Taonidium Pfeffer, 1900 Mantle calyx-shaped, posteriorly with short, very slender tip; fin terminating at the posterior end of the mantle or slightly surpassed by it; head slender; eyes stalked; no light organ on the ink-sack; tentacular club with 4 rows of suckers, the median of which are larger than the marginals. suhmii (Hoyle). Few, more or less doubtful species from various T. seas. ? Body Phasmatoteuthion Pfeffer, 1912 gelatinous; mantle slender; gladius with very long and slender cone-vane; head slender; eyes with thick stalks and vesicle-shaped light organ; median suckers of the tentacular club 981 many times larger than the marginals, on the distal part of the stalk with few pairs of small suckers. richardi (Joubin), near Europe insufficiently known, presumably P. juvenile form. Galiteuthis Joubin, 1898 Mantle slender, half-spindle-shaped, produced into an elongated which projects beyond the eyes; large tentacles arms strong; short, shaft large, broad lanceolate with membranes; distally head fin; suckers with tip, short, with smooth rings; with 2 rows of numerous alternating suckers and adhesive knobs, which form a small group on the carpal part; club juveniles with 4 rows of suckers, the lateral in of which later disappear, whereas the suckers of the 2 median rows are modified into hooks. G. armata Joubin Ocean, as well as (Fig. 881), in the in the northern Mediterranean Sea and Atlantic Pacific Ocean. Crystalloteuthis Chun, 1906 Mantle spindle-shaped, posteriorly pointed, with a few branched tubercles stalks, at the points of fusion; fins small, terminal; eyes on thick with 2 ventral half-moon-shaped light organs; arms small, with 2 rows of suckers; tentacles strong, on the shaft with 4 rows of suckers. 2, on the club with 482 r i •I\ Fig. 881. Galiteuthis C. glacialis armuto Joubin, Chun, in in dorsal view, 2/3 nat. size the Antarctic (after Chun). Ocean and one species {behringiana Sasaki) in the northern Pacific Ocean. Corynomma Chun, 1906 Mantle elongated calyx-shaped, and produced in the adult condition into a tip with moderately large fin; probably long head broad, anteriorly thinned pyramid-shaped, with fairly long pillar and long, slender eye stalks; eye small with a large ventral light organ; 2 ventral light organs on the ink-sack; rings of the arm suckers scarcely denticulate; tentacles long and strong; club with swimming membrane, median suckers larger than the marginals, distally with denticles. 1483 C. speculator Chun, in warm seas (Atlantic and Indian Oceans). Hensenioteuthis Pfeffer, 1900 Mantle membranous, calyx- or cylinder-shaped, teriorly gradually pointed; distinctly deflected extreme most cases pos- more or less from the long axis of the dorsal surface of the mantle; fin small, terminal; cephalic pillars in stalked, with a in ventral to the fin tip round most cases short and broad; eyes light organ; funnel very large; arms short; tentacles with only slightly broadened club. Subgenus Teuthowenia Chun, 1910 (synonym Owenia Prosch, 1847, non Chiaje, 1844). Fins very small, spatula-shaped, attached at the posterior end of the midline of the mantle dorsum; beak-shaped process of the eye moderately margin of the large, with large light organ extending to the H. (T.) megalops (Prosch). iris. Few species, in various seas. 982 Subgenus Hensenioteuthis s. s. Differing from Teuthowenia in having larger arms and stronger tentacles; process of the eye stronger; gladius broader. H. joubini (Pfeffer), in the Atlantic Ocean. (//.) Subgenus Helioocranchia Massy, 1907. Fin larger than in Teuthowenia, somewhat quadrangular, attached with the inner anterior corner of the lanceola, extending beyond in the midline by thinned, without its posterior end, here attached a connecting line; mantle posteriorly very gradually its tip curving ventrally; process of the eye large; arms well developed, the 3rd the longest; tentacles long and strong. H. pfefferi (Massy), in the northern Atlantic Subgenus Ascoteuthis Berry, shaped; 1920. Fins larger, nearly half-circle- mantle thick spindle-shaped, posteriorly with sharp somewhat surpasses stalks; the the fins; (//.) Ocean. tip which head with thick snout; eyes with thick 2 ventral arm pairs larger than the 2 dorsal pairs, with small suckers; tentacles long; club with 4 rows of very small suckers. H. (A.) corona (Berry), in the western Atlantic Ocean. Beak-shaped processes of the eyes have neither been figured nor described; the group may have the rank of a genus. Sandalops Chun, 1906 Mantle more or less calyx-shaped, posteriorly pointed; fins small, not completely terminal, in most cases distinctly separated from one another; eyes with long stalks and large, ventrally directed, beak-shaped processes, each bearing a small light organ; arms small; tentacles long; club scarcely broadened, with 4 rows of suckers; shaft with 2 rows, which extend to the center or to the base. 1484 melancholica Chun. S. Few species, some of which are doubtful, in the Atlantic Ocean. Bathothauma Chun, 1906 Mantle long, bell-shaped, posteriorly rounded, with roundish shortstalked fins widely separated from one another, close to the posterior end; gladius consisting of a narrow longitudinal band and a posterior transverse buckle situated between the fins bases, which are joined by a connective tissue band; funnel broad and short; cephalic pillars long and thin; eyes lobe; with very long stalks; with a large light organ below a short arms small and weak, the 3rd pair the longest; tentacles long and moderately strong; club scarcely broadened, triangular in cross-section, with 4 rows of stalked, bowl-shaped suckers; shaft with 2 rows of suckers. B. lyromma Chun (Fig. 882), in the Atlantic Ocean. Because of the peculiar gladius, Grimpe assumed a separate family 983 for this genus. Joubin, 1920, described a young animal under the alpha, which according to II. Body more shell him may belong Order to name Fusocranchia Bathothauma. OCTOPODA or less short, sack-shaped, with or without fins; internal rudimentary or completely reduced; light organs are seldom devel- oped; mantle dorsum nearly always fused with the body; the head at the bears 8 arms, in most cases differing only slightly in length, which are connected with one another by a more or less broad membrane; tentacles suckers in most cases unstalked, radially organized, absent; always arranged in valve; 1 often a third almost or 2 longitudinal rows; funnel in most cases without arm is hectocotylized; body cavity narrowed and pericardium reduced, in most cases 2 oviducts are developed; penis with a blind sack. Suborder Mantle shell in rudiment most cases with one is CIRRATA pair, seldom with 2 pairs of fins; a retained as a variably-formed fin support; arms more or less large, only slightly different in length, with very extensive velar membrane, each with a row of of cirri, fairly weak suckers and in addition 2 rows without distinct hectocotylus; radula often reduced; a right oviduct, an ink sack, and an intestinal sinus absent. 1485 - 'v.A_> 982 Fig. 882. Bathothauma lyromma Chun, (after I. STIRPS . in dorsal view, about 2/3 nat. size Chun). VAMPYROTEUTHACEA Mantle with wide ventral opening, sometimes with a locking apparatus similar to that in decapods, with one row of suckers and one or 2 pairs of in addition paired cirri, fins; arms with sometimes between the 1st and 2nd arms with a thread-shaped contractile process in a depression of the velar membrane; funnel with a valve; radula well developed. Inhabitants of the deep sea. 486 Family 1. Body arms; fairly small; cirri 983 suckers developed only on the distal part of the distinct; central plate Fig. Fig. VAMPYROTEUTHIDAE 883. Radular 884 Vampyroteuthis of the radula with one point (Fig. 883). row of Vampyroteuthis infernalis shown Chun (the infernalis Chun. narrow posterior fins are not here) (after Chun). Vampyroteuthis Chun, 1903 984 Mantle with 2 pairs of narrow fins, which are close to the posterior end and the dorsum; one pair of light organs at the base of the fins; gladius thin and transparent, in the form of a fairly narrow lamella, anteriorly shortly pointed, posteriorly gradually narrowed; arms with few small suckers on the distal part; a thread-shaped process on the velum absent. V. infernalis Chun (Fig. 884), in the Atlantic Ocean. Melanoteuthis Joubin, 1912 Mantle broad and process between the pair at the the base short, with a pair 1st and 2nd arms; bases of the fins; of fairly large light fins; a thread-shaped organs on the head and one without distinct constriction anterior to of the mantle; the gladius appears to be a saddle-shaped 1487 plate, broader than long; radular plates with short, fairly broad bases and sharp tips; funnel without locking apparatus; the suckers begin in most cases at the velar margin, the cirri in about the center between it and the mouth. A M. lucens Joubin. few species, in warm seas. Danateuthis Joubin, 1929 Similar to Melanoteuthis with a pair of fins and a thread-shaped process; small scattered light organs (?) and a pair of groups of densely aggregated white granulations; funnel with locking apparatus and valve; arm suckers stalked, the cirri extending beyond two-thirds of the distance of the velar margin from the mouth. D. schmidti Joubin, in the Gulf of Mexico. Retroteuthis Joubin, 1929 The arms are directed not anteriorly but toward the dorsum; funnel very large, with locking apparatus and triangular valve; mantle with one pair of fins; posterior to the bases sessile, in part stalked; is a pair of light organs; suckers in part small thread-shaped processes present. R. pacifica Joubin, in the Gulf of Panama. Hansenoteuthis Joubin, 1929 Mantle with 2 pairs of narrow fins; one pair of light organs at the bases of the posterior pair; one pair of fairly short processes between the 1st and 2nd arms; funnel with locking appartus. H. lucens Joubin, near the West Indian islands. Watasella Sasaki, 1920 Mantle with 2 pairs of fins, without light organs; one pair of thread- shaped processes present; eyes only slightly projecting; funnel with small half-moon-shaped valve, without locking appartus; arm suckers stalked. W. nigra Sasaki, near Japan. Hymenoteuthis Thiele, 1916 Mantle with one pair of somewhat absent; large, fairly narrow fins, which are attached more or less saddle-shaped; light organs thread-shaped processes on the very broad velum and a locking laterally; gladius 1488 apparatus on the funnel also absent; cirri from the mouth to the arm tips; central plate of the radula distinctly smaller than the neighboring plates, long and narrow points; a small scale-shaped the outer ones with marginal plate present; eyes greatly projecting, the left one larger; funnel largely fused with the head, without valve (?). H. macrope (Berry), near California. 2.FamUyLAETMOTEUTHTOAE 985 Arms with suckers to the mouth, although without (?) large; central plate large, tricuspid; either side with a small fin; arms body cirri; large, posteriorly fairly long, radula very rounded, on with broad velum. Laetmoteathis Berry, 1913 Characters of the family. L. So lugubris Berry, in the Pacific Ocean, near the Hawaiian Islands. far insufficiently II. known. STIRPS CIRROTEUTHACEA Mantle with narrow ventral opening, sometimes even fused with the funnel, with one pair of fins; without thread-shaped processes on the velum, without light organs and without ink sack; the radula shell is reduced; rudiment cartilaginous, saddle or buckle-shaped. 1. Family Arms moderately cartilage long, STAUROTEUTHIDAE in most cases with simple velum; shell buckle-shaped. Cirroctopus Naef, 1923 Synonym Grimpoteuthis Robson, Velum simple; cirri only slightly largest suckers; fins in C. mawsoni 1932. longer than the diameter of the most cases shorter than the width of the head. (Berry). A few species, in various seas. Stauroteuthis Verrill, 1879 Arms joined with the velum by secondary membranes; V-shaped; body long; fins small, attached in the center; shell cartilage cirri large. 1489 S. syrtensis Verrill, in the western Atlantic Ocean. Chunioteuthis Grimpe, 1916 Body broad and short; mantle margin fused with the funnel; arms with secondary velar membranes; of the suckers; C. fins cirri at least twice as long as the width about half as long as the width of the head. ebersbachii Grimpe, in the northerwestern Atlantic Ocean, and one species long, CIRROTEUTHIDAE Family 2. Arms (Robson)] near South Africa. [gilchristi with secondary velar membranes; in cirri most cases longer than the diameter of the suckers; body longish'; fins in most cases longer than the width of the head; shell cartilage saddle-shaped; fore-gut crop-shaped. Cirroteuthis Eschricht, 1938 Synonym Epulo Gistel, 1949. Characters of the family. C. mulleri Eschricht. A few species, in various seas. Subgenus Cirroteuthopsis Grimpe, 1920, differs in having the cirri placed not between but beside the suckers. C. (C.) massyae Grimpe. 986 ? Arms Froekenia Hoyle, 1904 very long, without velum (?); shell cartilage nearly half-circle- shaped; body oval; fins somewhat longer than the width of the mantle. F. clara Hoyle, near Panama. ? Body gelatinous, posteriorly pointed, with large fins attached fairly far forward; arms long and strong, with broad velum; suckers peculiarly spindle-shaped; C. Cirrothauma Chun, 1911 eyes reduced. murrayi Chun 987 3. Posterior (Fig. Family 885), in the northern Atlantic Ocean. OPISTHOTEUTHIDAE body developed only as a fairly flat hump with a pair of small fins; mantle opening small, surrounding the funnel; shell cartilage 1490 Fig. 885. Cirrothauma murrayi Chun, (after buckle-shaped, slightly curved; in ventral arms largely connected by the large velum; a radula absent. Opisthoteuthis Verrill, 1883 Characters of the family. view Chun). 1491 O. agassizii Verrill. The named species A is few species, in various seas (Fig. 886). stated to differ from the remaining in that the shell cartilage consists of 2 halves (?); for this reason Berry, 1918, has separated the other species as subgenus Teuthidiscus. (O. (T.) pluto Berry). depressa Ijima Fig. 886. Opisthoteuthis 3/5 nat. size (after Ijima Suborder Mantle without long, in fins, as most cases with 1 most cases hectocotylized & & Ikeda, in lateral and dorsal view, about Ikeda and after Meyer). INCIRRATA a rule without shell rudiment; arms or 2 rows of suckers, without in the cf; cirri; more or less one arm in funnel without valve; radula well developed; both oviducts retained. I. Body in length, STIRPS BOLITAENACEA very soft and gelatinous, without distinct cartilage; arms differing with thin, more or less broad velar membrane, and with one row of suckers; jaw soft; radular plates as a rule (Fig. 887); eye cavity open. with greatly broadened bases 1492 Fig. 887. Left half of a radular row of Bolitaena (Eledonella) pygmaea 1. 988 Arms fairly laterally directed; short, Family Verrill. BOLITAENIDAE with moderately broad velum; eyes roundish, mantle widely open, not fused with the funnel; funnel organ A-shaped; central plate of the radula on either side with 2 or 3 accessory cusps, the 2 intermediate plate pairs in most cases with 4 teeth. Japetella Hoyle, 1885 Synonyms Chunella Grimps, Sasaki, 1920, noon Kiikenthal, 1902; Bolitaenella 1922. Optic nerves not greatly elongated; hectocotylized arm with a few enlarged suckers. J. Few prismatica Hoyle. species, in various seas. Bolitaena Steenstrup, 1859 Optic nerves elongated. Few species, in various seas. Subgenus Bolitaena s.s. The ganglion pedunculatum is close to the ganglion opticum. B. (B.) microcotyla Hoyle. Subgenus Eledonella Verrill, from the ganglion opticum; suckers. B. (£.) pygmaea 2. Arms 1884. Ganglion pedunculatum farther right 3rd arm in the cf with few enlarged (Verrill) (Fig. 888). Family AMPfflTRETIDAE long, with broad velum; eyes cone-shaped, dorsally close to one another; funnel fused with the mantle in the center, so that on either side this has a small opening; hectocotylized of small knobs and thickened proximal to arm it distally flattened with 2 rows and broadened with an angulate furrow; funnel organ w-shaped; radula similar to that in Bolitaenidae. 493 Fig. 888. Bolitaena (Eledonella) (after pygmaea (Verrill) Chun). Amphitretus Hoyle, 1885 Characters of the family. A. pelagicus Hoyle. Few species, in most cases doubtful, in various seas. 3. Family VITRELEDONELLIDAE Arms in most cases long, at the base joined by a thin velar membrane; eyes moderately large, laterally directed; mantle broad and short, 989 not fused with the funnel, funnel small; central plate plate with on organ w-shaped; radula very either side with 2 lateral denticles; inner intermediate one pointed and one low denticle, outer intermediate plate with only one denticle on the moderately broad base; strikingly small. Robson has included all viscera and the gills this family in the following stirps. — 1494 Vitreledonella Joubin, 1918 Characters of the family. Few species, in the Atlantic Ocean. V. richardi Joubin. V. translucida Robson seems organ is to be considerably a very obtusely angled band; the II. Mantle without sometimes STIRPS 3rd arm hectocotylized. is OCTOPODACEA arms more or fins; fairly large left different; the funnel less long, with suckers, without cirri; velar or 2 rows of 1 membrane in most cases narrow; shell completely rudimentary; central plate of the radula well developed, sometimes with accessory cusps; inner intermediate plate small, the outer present (Fig. 889); hectocotylized, with a one with broad base, a scale-shaped marginal plate one 3rd arm — in sperm groove, which most cases the in right most cases ends shaped papilla (calamus), and a spoon-like terminal part on in a cone- (ligula), often with transverse furrows, otherwise the sexes are not strikingly different. Fig. 889. Half radular row of Octopus vulgaris Lamarck 1. An Family (after Naef). OCTOPODIDAE ink sack present; gills with inner and outer lamelae; a crop in most cases well developed. A. Subfamily Ozaeninae Arms with one row of suckers; eggs large. Living in most cases in the vicinity of the shore. Ozaena Rafmesque, 1814 (Ozoena) Synonym Eledone Leach, 1817, non Eledona Heledone L. Agassiz, 1846; Epistrophea Latreille, Gistel, 1848; Hallia 1796; Rochebrune, 1884; Hoylea Rochebrune, 1885; Moschites (Schneider, 1784) Hoyle, 1901. 1495 Distal suckers of the O. Atlantic arms modified calamus and ligula are in the cf; on the hectocotylus. indistinct moschata (Lamarck). A couple of species, in the northern Ocean. Pareledone Robson, 1932 Differing from the preceding genus by distinct development of the calamus and P. oviducts short; vagina and spermatophores large. ligula; charcoti (Joubin). A few species, in the southern seas. Velodona Chun, 1915 Arms broad ventral membranes; hectocotylus with distinct large, with calamus; the funnel organ consists of 2 symmetrical, anteriorly indented plates; 990 central of the radula without accessory cusps; inner plate intermediate plate with fairly thick point; outer intermediate plate with strong point and short base; lateral plates short and thick. V. togata Chun, near East Africa. B. Subfamily An warmer Octopodinae ink sack present as a rule; eggs small. In most cases living in seas near the shore. Octopus Lamarck, 1798 Synonym Polypus (Schneider, 1784) Hoyle, 1901. Arms with moderately broad, as a rule symmetrical right velar membrane; 3rd arm hectocotylized; mantle opening wide; penis diverticulum simple. Subgenus Octopus rule with 2 seldom more than Several species, Amphioctopus species is s. s. Arms not strikingly different in length, as a rows of suckers, which are not modified 1 1 said to various seas. in for in the ? ; gill lamellae penis diverticulum short. O. (O.) vulgaris Lamarck. ; P. Fischer, 1882, erected a genus membranaceus Quoy & Gaimard, because this have a membrane on both sides, although it is not O. considered as characteristic. Subgenus Macrotritopus Grimpe, 1922. The 3rd arms significantly (A/.) equivocus Robson. Few species. Subgenus Tritaxeopus Owen, 1881. Arms with 3 rows of suckers. O. (T.) cornutus (Owen). longer than the remaining. O. 1496 Subgenus Macroctopus Robson, 1928. Body long and slender; distal suckers on the arms in the 9 modified into papillae; hectocotylus long; gills long, on either side with 13 or 14 lamellae. O. (M.) maorum Hutton. 2 species, near New Zealand. Subgenus Enteroctopus Rochebrune Octopus s. s., & Mabille, 1889. Similar to although with long, thin penis diverticulum. O. (£.) membranaceus (Rochbrune & Mabille). del Fuego and the Falkland Islands. A couple of species, near Tierra According to Robson, the typical species of Eledonenta Rochebrune, 1884 ifilholiana Rochebrune) belongs to Octopus. Cistopus Gray, 1849 The velar membrane has on the without calamus and of which 8 pockets between the arms, the openings side at about the 3rd suckers; oral lie hectocotylus ligula. indicus (Orbigny), in the Indian Ocean. C. ? Pinnoctopus Orbigny, 1845 Mantle with a broad lateral lamella similar to that in Sepia. cordiformis (Quoy P. considers it possible that this & is Gaimard), near New Zealand. Robson Octopus maorum with a membranous web. Joubinia Robson, 1929 Velar membrane between the arms equally broad and continued only on these; arms equally long; mantle opening partly closed; ligula of the hectocotylus with broad margin; penis diverticulum long, with a slightly roundish process at the base. J. fontaniana (Orbigny), in the southern Pacific and Indian Oceans, as well as one species [campbelli (E. Smith)], near New Zealand. Scaeurgus Troschel, 1857 991 Arms and velar projecting calamus membrane equal; 3rd left and large ligula with inrolled margins; penis diverticulum long. S. arm hectocotylized, with unicirrhus (Orbigny), in various seas. 1497 Paroctopus Naef, 1923 Synonym Pseudoctopus Grimpe, 1925. Arms in most cases fairly short; hectocotylus on the 3rd right arm long and narrow; eyes fairly large. & digueti (Perrier P. Rochebrune). A few mainly species, in the northern Pacific Ocean. Macrochlaena Robson, 1929 Mantle and head long and narrow; arms very short with velar membrane; funnel without freely projecting part; paired; outer intermediate plate of the radula with a median fairly broad funnel organ point; d organs without appendage. M. winckworthi (Robson), near India. Pteroctopus P. Fischer, 1882 Arms with small suckers and broad velar membrane; hectocotylus on the 3rd left arm, simple, with small calamus; funnel organ paired; ink sack not or only slightly sunken into the liver. P. tetracirrhus (Delle Chiaje), in the Mediterranean Sea and Atlantic Ocean. Hapalochlaena Robson, 1929 Arms rings; short with broad velar membrane; integument with pigment ink sack very small. H. lunulata (Quoy ? & Gaimard). A couple of species, near Australia. Haptochlaena Grimpe, 1922 This genus was erected for the insufficiently Grimpe and Robson. the juvenile H. alberti Joubin, and is known H. chuni doubtful according to C. Subfamily Bathypolypodinae Without ink sack; mantle opening more or cases short, with spermatophores seas. 1 less narrow; arms in most or 2 rows of suckers; crop small or absent; eggs and large. Living in the deep sea and in most cases in cold 1498 Benthoctopus Grimpe, 1921 with 2 rows of suckers; mantle opening more or less narrow; Arms radula normal. Living in most cases in deep water. B. piscatorum According Grimpe), is to (Verrill). A few species, in various seas. Robson, Atlantoctopus Grimpe, 1921 (pseudonymus not separable from Benthoctopus. Teretoctopus Robson, 1929 Integument smooth; arms short with 2 rows of suckers and broad velar membrane; funnel organ quadripartite; radula normal; crop distinctly developed; posterior salivary glands weak. T. indicus Robson. 2 species, near India. Grimpella Robson, 1928 992 Integument with small warts; hectocotylized arm very short, with strikingly deep and long calamus, the remaining arms long; funnel organ of the radula very weak, without point; bipartite; inner intermediate plate sperematophores loop-shaped. G thaumastocheir Robson, near South Australia. Bathypolypus Grimpe, 1921 Arms medium-sized, with 2 rows of suckers, hectocotylus normal; membrane moderately broad; funnel organ bipartite; central plate velar of the radula with a long point without accessory cusp, the remaining plates normal; oviduct gland in B. arcticus (Fig. 890), one (Prosch). Few most cases species, in the northern Pacific large. mainly in the Atlantic Ocean Ocean. Graneledone Joubin, 1918 Integument dorsally warty; arms medium-sized, with one row of suckers; hectocotylus small; central plate of the radula with fairly broad, triangular cutting edge and small lateral cusps; inner intermediate plate well developed; cutting edges of the outer intermediate plate and of the lateral plate strong; gill very small; penis with large, sack-shaped diverticulum. G. verrucosa (Verrill). A couple of species, in various seas. 1499 890. Bathypolypus lentus (Verrill) Fig. (after Verrill). Bentheledone Robson, 1932 Arms membrane more or strong, fairly broad; long, less organ funnel with one row of suckers; [in B. ? albida (Berry)] velar simple, broadly V-shaped; central plate of the radula broad, with simple point; and weak; outer intermediate plate with innter intermediate plate small a short triangular point; lateral plate and marginal plate with projecting points; oviduct completely separate; vagina very short and wide; gill small. B. and rotunda (Hoyle), in the southern seas off Kerguelen, Australia, ? Chile. It seems uncertain whether "Moschites" albida Berry belongs here. Thaumeledone Robson, 1930 Body short and thick; arms short, with fairly and one row of suckers; funnel organ 993 broad velar membrane bipartite; gills small, with 5 or 6 lamellae; radula with strong central plates of similar form to those in Bathypolypus; T. brevis all other plates rudimentary. (Hoyle), near Montevideo; a 2nd species (71 gunteri Robson), near Sourth Georgia. III. STRIPS ARGONAUTACEA Sexes more or less different; arms as a rule with 2 rows of suckers; the hectocotylized arm long, in body; eggs small and numerous. mature condition detached from the 1500 1. Family ALLOPOSIDAE soft, ? large, d smaller; arms fairly short, with broad, strong membrane; suckers occasionally not very numerous and partly Body velar uniseriate; mantle dorsally fused with the body, ventrally with broad opening; funnel short; funnel organ w-shaped; central plate of the radula with distinct lateral cusps on the broad base; inner intermediate plate with distinct point; outer intermediate plate strong; 3rd right arm hectocotylized, with 2 lobed membranes; a seminal vesicle and a penis-like process, it develops in a cavity anterior to the right eye. Alloposus Verrill, 1880 Characters of the family. A. mollis Verrill (Fig. 891). Fig. Few species, in various seas. 891. Alloposus mollis Verrill (after Verrill). Haliphron Steenstrup, insufficiently described. 1859, may refer to Alloposina Grimpe, this genus, but is 1922 {albatrossi Robson) = Bolitaena microcotyla Hoyle, 1904, non 1886, may be based on a young specimen of an Alloposus 1929 (danai Joubin). 2. Family species, as also is Heptapus Joubin, TREMOCTOPODIDAE Mantle dorsally fused with the head by a membrane perforated by 2 large holes; an integumental pore ventral arms; dorsal is also developed at the base of the arms of the ? much longer than the remaining, they are joined with one another and with the 2nd arms by a large velar membrane, the other two pairs of arms not joined; funnel short; funnel organ formed of a few ridges; a locking apparatus consists of a fairly long and deep mantle portion and a weak triangular or roundish head portion; 1501 of the radula with fairly large lateral cusps; both intermediate one point; hectocotylus long, with 2 rows of suckers, attached central plate plates with to which is a thin "penis" and opening in the is proximal half at is a row of thin processes, in the distal part the end an oval seminal vesicle with terminal present; the hectocotylus develops in a sack attached between the funnel and the eye. Tremoctopus Delle Chiaje, 994 Synonym 1 829 Philonexis Orbigny, 1835. Characters of the family. T. violaceus Delle Chiaje, in various seas. 3. Head with one Family OCYTHOIDAE pair of ventral integumental pores; arms slender, without distinct velar membrane; suckers projecting, the distal ones in 2 funnel organ formed of a large A-shaped and 2 rows; funnel large; longish parts; locking apparatus on the funnel formed of a strong curved cartilaginous process with a deep pit; central plate and inner intermediate plate of the radula with distinct lateral cusps; ? large, ventrally with stiff warts connected by ridges; water canals paired; oviduct with a short, thick proximal part, and a long, small, 3rd right arm suckers in 2 rows, thin, coiled, terminally-widened distal part; hectocotylized, with long flagellum, and it numerous o* flat develops in a stalked sack and then separates from the animal (Fig. 892). Fig. 892. Hectocotylus of Ocythoe tuberculata Rafinesque (after Jatta). Ocythoe Rafinesque, 1814 Synonym Parasira Steenstrup, 1861. Characters of the family. O. tuberculata Rafinesque, in the Mediterranean Sea, Atlantic and Pacific Oceans. 502 4. Female with a which is thin, Family ARGONAUTIDAE unchambered, transversely wrinkled not firmly fused with the animal but is large lobe-shaped expansions of the dorsal arms, spiral shell, produced and held by it serves partly for the protection of the animal, partly as broad space; arms without velum, with 995 2 rows of suckers; cartilaginuous locking apparatus on the funnel knobshaped, deepened in the center, funnel organ similar to that in Ocythoe; water canals rudimentary; oviduct very long and coiled, spherical, closely spaced thickenings; hectocotylized, very long, its distal 3rd left at the end with arm of the small part whip-shaped. Argonauta Linne, 1758 Characters of the family. A. argo Linne (Fig. 893). A few species, some of them doubtful, in various seas. Fig. 893. Shell of Argonauta argo Linne (diameter 16 cm). EDITORS' NOTE: "Additions and Corrections to Parts 1 and 2" on these pages have 1010 been incorporated as footnotes to appropriate text throughout this 995- translation. 1503 10 l! Alphabetic Index of Genera, Subgenera and Sections mentioned in Part New names are spaced (in bold face in this translation); synonyms printed in italics. Abisa 1225 Abra 1383 Abralia 1453 Abraliopsis 1453 Abranda 1383 Acanthocardia 1337 Acanthocardium 1337 Agina 1398 Agriodesma 1417 Agriopoma 1345 Ainohelix 1093 (pt. 2) Alasmidonta 1264 Alasminota 1265 Alasmodonta 1264 Acanthosepia 1442 Alectryonia 1242 Acanthosepion 1442 Alicia 1422 Acar 1212 Acardo 1337 Aligena 1330 Acesta 1238 Alloposina 1500 Acharax 1210 Acila 1203 Aeolus 1353 Acostaea 1284 Alloposus 1500 Allogramma 1416 Allorossia 1444 Alloteuthis 1450 Alluroteuthis 1466 Acreuciroa 1429 Aloidis 1400 Acrololigo 1450 Amathinoides 369 Acroteuthis 1450 Actinobolus 1289 Amblema 1260 Amesoda 1297 Amesodesma 1362 Actinonaias 1271 Amesodon 1297 Acruroteuthis 1450 (pt. Acuticosta 1253 Amiantis 1345 Adacna 1340 Amphicardium 1335 Amphichaena 1378 Adacnarca 1217 Adamussium 1232 Amphicoelina 1096 Adasius 1380 Amphidesma 1380 Adipicola 1220 Amphilepida 1327 Amphinaias 1260 Amphioctopus 1495 Amphithaea 1348 Amphitretus 1493 Amplisepia 1442 Adrana 1209 Adranellal208 Adula 1223 Adzharia 836 (pt. 2) Aeglia 1272 Aenigma 1240 Aequipecten 1233 Aeretica 1385 Aetheria 1283 Amusium 1231 Amussium 1231 Amygdala 1355 Amygdalonaias 1270 Afristrepataxis 1144 (pt. 2) Amygdalum 1221 Afrocardium 1338 Agaria 1289 Anadara 1213 Anadontina 1264 III (pt. 1) 2) 1504 Anaglyphula 920 (pt. Arcopagia 1384 2) Anaitis 1352 Arcopaginula 1385 Arcopella 1384 Anapa 1322, 1360 Anapelllal360 Anatina 1367, 1424 Arcopsis 1212 Arcoptera 1211 Anatinella 1371 Arctica 1301 Anchomasa 1407 Arctinula 1230 Arctoe 1348 Ancistrochirus 1455 Ancistroteuthis 1460 Andreaesepia 1442 Anelasmodonta 1264 Arctosepia 1442 Anfilla 1319 Arenaria 1383 Arcturus 1289 Arculus 1308 Angulus 1391 Arenomya 1403 Anisocorbula 1401 Argina 1213 Anisodonta 1307 Anodonta 1267 Anodontia 1318 Argonauta 1502 Argyrodonax 1361 Anodontites 1280 Anodontoides 1265 Armida 1301 Armsia 814 (pt. Anodontostrea 1242 Arnoldina 1267 Arkansia 1263 2) Anomala 1293 Aroapyrgus 207 Anomalocardia 1352 Anomalocardia 1213 Arotonaias 1274 Artemis 1348 Anomalocranchia 1479 Anomalodiscus 1351 Arthropteron 1281 Anomia 1239 Anonica 1227 Antalis 1196 Anticlinura 572 (pt. Arthritica 1321 Artusius 1395 Arytene 1425 ,fca (pt. 1348 Asaphis 1376 1) Anticorbula 1401 Antigona 1349 Asbjornsenia 1330 Antilla 1319 Ascarosepion 1442 Antitragus 1032 Aphrodite 1337 1) Ascarosepia 1442 (pt. Ascoteuthis 1483 Asmidia 1301 Aspalima 1215 2) Aphrodora 1345 Aplodon 1279 Apolymetis 1386 Aporema 1420 Appius 1266 Aquaria 1425 Area 1211 1012 Aspatharia 1281 Aspergillum 1425 Aspidopholas 1410 Aspidotomium 1020 (pt. Astarte 1285 Asteroteuthis 1453 Architeuthus 1463 Asthenoteuthion 1454 Archivesica 1299 Asthenothaerus 1422 Arcidens 1264 Atactodea 1362 Arcidopsis 1257 Atlantoctopus 1498 Arcinella 1289, 1333, 1399 Atopodonta 1299 Atrina 1228 Arconaia 1258 2) 1505 Aulacomya 1224 Bathycorbis 1320 Aulus 1377 Bathypolypus Auriscalpium 1424 Bathyteutbis 1466 Aurora 1247 Batissa 1294 Beguina 1290 Austrodosinia 1348 Austroharpa 523 (pt. 1498 1) Belchlamys 1233 Austrolima 1237 Bellucina 1315 Austromactra 1364 Bentharca 1212 Austropteria 1227 Bentheledone 1499 Austrorossia 1445 Benthocardiella 1292 Austrosarepta 1216 Benthoctopus 1498 Austroturquetia 1330 Benthoquetia 1330 Austrovenus 1351 Benthoteuthis 1466 Autonoe 1322 Avicula 1227 Aximedia 1261 Axinaea 1214 Axinaeoderma 1214 Axinodon 1314 Bequania 1314 Axinopsis 1315 Blainvillia 1356 Bernardina 1287 Berryiteuthis 1462 Berryteuthis 1462 Biapholius 1398 Bineurus 1250 Axinulus 1314 Bolitaena 1492 Axinus 1314 Bolitaenella 1492 /Izara 1402 Bonartemis 1349 Azarella 1290 Bonneviia 731 Azar/a 1289 Bontaea 1423 Aror 1379 Bornia 1322 2) (pt. Borniola 1322 Babelomurex 453 (pt. Bactronophorus 1414 Balwantia 1252 Bankia 1414 1) Bothrocorbula 1401 Botula 1223 Botulina 1222 Brachidontes 1221 Bankiellal415 Brachioteutbis 1467 Baphia 1245 Barbala 1266 Barbatia 1212 Barclayia 1326 Bariosta 1260 Baraea 1407 Brachyanodon 1267 Barrimysin 1325 Brevinucula 1262 Bartlettia 1283 Brachyodontes 1221 Brachypyrgula 227 (pt. Brazzaea 1281 Brechites 1425 Brephodrillia 547 Briophila 1217 Barynaias 1262 Bryopa 1425 Bassina 1352 Bryophila 1217 Basterotia 1307 Bucardia 1300 Bathothauma 1484 Bucardium 1300 Bathoxiphus 1196 Bullata 1260 Bathyarca 1212 Bullella 1264 Bathycardita 1289 Bulloideus 1276 (pt. 1) 1) 1506 Bunodus 1425 Burtonia 1281 Capsaefonnis 1275 Capsella 1374 Bushia 1422 Capsella 1377 Butor 1424 Butorella 1424 Byssanodonta 1298 Byssoarca 1211 Byssomya 1398 Cacodaphnella 567 Capsula 1376 Cardila 1372 Cardiocardital289 (pt. 1) Cacophonia 1369 Cadmusia 1409 Cadulus 1194 Cardiomya 1433 Cardissa 1339 Cardita 1288 Carditamera 1290 Carditella 1291 Cardites 1289 Carditopsis 1291 Caecella 1361 Cardium 1337 Caelatura 1248 Carinogyraulus 783 Caenonaias 1262 Carocolla 1127 Cafferia 1258 Carswellena 99 Calcaraea 1423 Caryatis 1345 Calceola 1264 Cassidulella 763 Cassidulina 763 Callicistronia 1353 Castalia 1276 Castaliella Callista 1346 Castalina 1276 Catelysia 1354 Caudiculatus 1253 Callithaca 1355 Cavatidens 1318 Callizona 1345 Cavilucina 1316 Callizonata 1345 Centrifuga 436 Cerana 1348 1 344 Callogonia 1299 (pt. Cerastes 1337 Ceratisolen 1395 Callonaia 1277 Ceratobornia 1322 Callucina 1316 Cerceis 1341 Calo bates 1414 Ceronia 1362 Calopodium 1417 Ceropsis 1291 Calpitaria 1345 Cetoconcha 1431 Calyculina 1298 Cetomya 1431 Chaena 1405 Chaenopaea 1399 1410 Cameronia 1282 Camptonectes 1231, 1233 Cancelloconus 977 (pt. 2) Canthyria 1262 Canthyria 1257 Chamelea 1352 Chamostrea 1419 Capisteria 1373 Charitodoron 471 Capsa 1375, 1376 Charybditeuthis 1456 Calyptopholas 1) Cerastoderma 1337 Callolima 1238 Calyptogena 1290 2) 2) 1277 Callistotapes 1355 Callocardia (pt. (pt. Calliteuthis 1464 Calloarca 1212 2) 2) (pt. 1) Callanaitis 1352 Calliscapha 1282 (pt. (pt. Chama 1333 Chamaearionta 1097 (pt. Chamberlainia 1256 (pt. 1) 2) 1507 1013 Chaunoteuthis 1459 Clausinellal351 Chelidonopsis 1282 Clavagella 1425 Chelidonura 1282 Cleidothaerus 1419 Cheloteuthis 1461 Clelandella 74 Chimaera 1228 Chion 1374 Chione 1351 Chione 1346 Clementia 1356 Chionella 1346 Clessinella 1298 (pt. 1) Cleone 1266 Cleotrivia 403 (pt. 1) Clepsydra 1426 Chioneryx 1351 Clessinia 1297 Chiridioteuthis 1473 Cletella 1297 Chironia 1322 Chirosoma 1473 Chiroteuthis 1472 Clidiophora 1418 Chunoteuthis 1466 Clinopegma 466 (pt. 1) Clinuropsis 572 (pt. 1) Clossonnaria 1413 Clotho 1313, 1398 Clunaculum 1379 Cnesterium 1209 Coccodentalium 1 1 96 Cochlodesma 1423 Codakia 1319 Codokia 1319 Coelodon 1418 Coelomactra 1366 Coeloteredo 1413 Cokeria 1260 Colletopterum 1267 Colorimactra 1366 Columba 1280 Columplica 1025, 1085 Cibota 1211 Comitileda 1206 Cinetodonta 1421 Circe 1344 Complanaria 1265 Compressidens 1196 Circenita 1343 Compsomyax 1356 Circomphalus 1351 Cirrobrachium 1472 Comus 1343 Chiroteuthoides 1473 Chiroteuthopsis 1475 Chirothauma 1473 Chlamydella 1230 Chlamydoconcha 1328 Chlamys 1233 Chloromya 1224 Chondropomella 191 (pt. 1) Chondrosepia 1449 Choristodon 1359 Christadens 1252 Chromodoris 709 (pt. 2) Chrysopseudodon 1250 Chunella 1492 Chunioteuthis 1489 Compsoteuthis 1454 Cirroctopus 1488 Conchocele 1314 Cirroteuthis 1489 Conchodromus 1269 Cirroteuthopsis 1489 Condylocardia 1292 Cirrothauma 1489 Congeria 1311 Cistopus 1496 Clamturris 554 Coniglobus 1075 (pt. 1) Clathrodon 1363 Clathrotellina 1388 (pt. Connollya 879 (pt. 2) Conothais 447 (pt. 1) Conradilla 1274 Claudiconcha 1359 Contradens 1252 Clausaria 1413 Cooperella 1358 Clausina 1314, 1350, 1352 Coralliophaga 1392 2) (pt. 2) 6 1508 Corbicula 1294 Corbiculina 1295 Cucullaeal213 Cucumeria 1246 Corbis 1320 Cucurbitula 1405 Corbula 1376, 1400 Corbulomya 1406 Cultellus 1396 Corculum 1338 Cordium 1337 Cumberlandia 1245 Cordula 1296 Cuna 1287 Coriareus 1330 Cunearca 1213 Coripia 1289 Cuneocorbula 1401 Cornea 1297 Cuneopsidea 1248 Corneocyclas 1297 Cuneopsis 1258 Corneola 1297 Cuneus 1347, 1373 Cultrensis 1396 Cumingia 1382 Corynomma 1482 Cunicula 1262 Cosa 1216 Cuspidaria 1431 Cosmetopsis 1215 Cosmopseudodon 1250 Cyamiomactra 1303 Cyamium 1304 Costokidderia 1309 Cyanocyclas 1295 Costovalvata 175 (pt. 1) Cyathodonta 1421 Cycladicama 1312 Cranchia 1478 Crassatella 1286 Cycladina 1297, 1322 Crassatina 1286 Cycladoconcha 1332 Crassina 1285 Cyclas 1297 Crassinella 1286 Cyclina 1349 Crassitesta 1266 Cyclinella 1349 Crassivenus 1351 Cyclocalyx 1297 Crassostrea 1242 Cyclocardia 1289 Cratis 1215 Cyclochlamys 1231 Crenatula 1224 Cyclomactra 1366 Crenella 1220 Cyclomonilearia 1106 Crenellodon 1220 Cyclomya Crenodonta 1260 Cyclonaias 1260 Crista 1343 Cyclopecten 1230 Cristaria Cyclotellina 1386 1266 Crumenasepia 1442 Cycloteuthis 1458 Cryptodon 1314, 1369 Cryptogramma 1352 Cydippina 1387 Cryptomya 1403 Cryptonema 1352 Cylindromitra 519 Crystalloteuthis (pt. Ml 1481 Ctenamusium 1231 Cydippe 1387 Cylindrica 1258 Ctenoconcha 1204 Ctenodesma 1252 Cymatoica 1388 Cyphoxis 1211 Cyphus 1413 Cypraeerato 402 Ctenoides 1237 Cypricardia 1302 Ctenocardia 1339 (pt. 1) Cymatocyclas 1297 Ctenopteryx 1467 Cypricia 1367 Cucioteuthis 1457 Cyprina 1301 (pt. 1) 2) 1509 Cyprinella 1293 Devonia 1331 Cypriniadea 1301 Diabolica 1215 Cyprogenia 1269 Dianisotis 1266 Cyrachaea 1317 Cyrena 1294 Cyrenastrum 1297 Cyrenella 1294 Cyrenocapsa 1293 Cyrenodonax 1294 Cyrenodonta 1296 Cyrenoida 1296 Diaphanoteuthis 1473 Cyrilla 1215 Cyrillista 1014 1215 Diaphoromactra 1364 Diaurora 1247 Diberus 1223 Didacna 1339 Didonta 1398 Digitaria 1285 Dimya 1229 Dimyodon 1229 Dinocardium 1336 Cyrillona 1215 Dinoteuthis 1463 Cyrtodaria 1399 Diondonta 1386 Diodus 1293 Cyrtonaias 1273 Cyrtopinna 1228 Dioeciostrea 1242 Cyrtopleura 1407 Dione 1346 Cyrtosolen 1380 Diphtherosepion 1443 Cytherea 1350 Diplodon 1276 Diplodonta 1312 Dacosta 1425 Diplodontina 1323 Dacrydium 1219 Dilodontites 1279 Dactylina 1408 Damalis 1245 Diplopseudodon 1250 Diplothyra 1410 Dipsas 1266 Dalliella 1254 Danateuthis 1487 Dischides 1194 Daphne 1211 Daphnoderma 1211 Disconaias 1273 Darina 1370 Discors 1335 Discomya 1249 Davila 1360 Divaricardium 1335 Davisia 1308 Divaricella 1317 Decadopecten 1233 Decipula 1330 Divariscintilla Decorisepia 1443 Dolomena 382 Decurambis 1264 Delphinonaias 1273 Donacicardium 1373 Donacillal362 Deltachion 1374 Deminucula 1203 Donacina 1375 Dendrostrea 1242 Dentalium 1196 Doratopsis 1472 1327 Dolichosirius 366 Donacilla 1391 Donax 1373 Denticosa 1216 Doratosepia 1442 Dentilucina 1316 Doratosepion 1442 Dentipecten 1233 Dorvillea 1383 Dermatomya 1431 Doryteuthis 1449 Desmoteuthis 1480 Despoenella 131 (pt. 1) Dosidicus 1471 Dosina 1349 (pt. (pt. 1) 1) 1510 Dosinella 1348 Dosinidia 1348 Enigmonia 1240 Ennucula 1202 Enocephalus 1311 Dosinisca 1349 Enoploion 1454 Dosinorbis 1348 Enoploteuthis 1455 Dosinia 1348 Dosinula 1350 Doxander 382 Enoptroteuthis 1475 (pt. Ensatella 1398 1) Drechselia 1477 Ensiculus 1396 Dreissena 1311 Ensidens 1251 Driessena 1311 Ensis 1398 Dromus 1269 Entalinall95 Dubioteuthis 1463 Entaliopsis 1197 Dufoichaena 1405 Dulcerana 423 Entalis 1196 (pt. Enteroctopus 1496 1) Dyctydiopsis XAll Entodesma 1417 Dysnomia 1274 Entomopsis 1467 Eastonia 1368 Eocyclina 1349 Eburneopecten 1233 Eolymnium 1258 Echinochama 1333 Eostrea 1242 Entovalva 1331 Eoteredo 1413 Ectorisma 1431 Ectosinum 394 (pt. Ephippium 1241 1) Ephippodonta 1328 Epicodakia 1 320 Edenttellina 1310 Egeria 1 375 Egeta 1293 Epidirella 554 (pt. 1) Egetaria 1293 Epidirona 554 Egraca 1315 Epilepton 1308 Elathia 1318 Epilucina 1316 Electroma 1227 Electromactra 1367 Epioblasma 1274 Episiphon 1186 Eledone 1494 Epistrophea 1494 Eledonella 1492 Epitychusa 1444 Epulo 1489 Equichlamys 1234 Eremarionta 1097 Ergalatax 441 (pt. Erodona 1402 Eledonenta 1496 Elegantula 1381 Elizia 1376 402 (pt. Ellipsaria 1260 Elliptio 1262 Ellatrivia 1) 1) Erycina 1321 Elongaria 1254 (pt. 2) Etheria 1283 Embla 1430 Euaethiops 899 Emmericia 216 (pt. 1) Empleconia 1215 Endemoconus 577 (pt. Eucallista 1346 Endopleura 1383 (pt. Eryx 1321 Escalima 1238 1384 Elysiobranchus 684 1) Ervilia 1361 Elliptoideus 1263 Elliptotellina (pt. Eucardium 1337 1) Eucharis 1307 Euciroa 1429 (pt. 2) 2) 1511 Felipes 1233 Eucleoteuthis 1471 Felipponea 171 Eucrassatella 1287 Eudaphne 571 (pt. 1) Eugaimardia 1309 Fimbria 1320 Eugemmula 554 Fischeria 1375 (pt. 1) Euglesa 1296 Fissidentalium Eulopia 1317 1 1 97 Euphrata 1267 Fwru/a 1397 Fistulana 1405 Flexopecten 1233 Fluctiger 1343 Fluminina 1297 Fluviolanatus 1220 Foegja 1426 Fontinalina 1297 Eupisidium 1297 Foramelina 1225 Eupoleme 1324 Euprymna 1447 Euryanodon 1280 Fossarina 1297 Eurynaia 1262 Fossula 1280 Eurynia 1262 Fossularca 1212 Eurytellina 1390 Fragilia 1386 Eumarcia 1354 Eumodiolus 1220 Eumontrouziera 1382 Eumulleria 1284 Eumytilus 1223 Eupera 1298 Forskaliopsis 73 402 Fossatrivia Eusepia 1442 Fragum 1334 Eusepiola 1447 Franklinia 1444 Eustylon 1369 Frenamya 1418 Eu tapes 1355 Friersonia 1272 (pt. 1) Eutriphora 327 1) Fulcrella 1307 (pt. 1) Fundella 1226 Euvola 1234 Furcella 1413 Euzebrinus 1005 Fusconaia 1259 Euzygaena \A11 Exilioidea 466 (pt. Eximiothracia 1422 Fusocranchia 1484 1) Fusomurex 453 Fustiaria 1 1 96 Exoleta 1348 Exosiperna 1220 Gabillotia 1267 Exotica 1391 Gadilall94 Gadus 1194 (pt. (pt. 1) Fulvia 1336 Eutivela 1348 Extra 541 (pt. Froekenia 1489 Eutellina \392 Euterebra 582 1) Fidenas 1447 Eufira 1282 1015 (pt. Fenestella 1240 1) Gafrarium 1343 Fabella 1307 Gaimardia 1309 Fabulina 1391 Galactella 1212 Fallartemis 1349 Galatea 1375 Fastimysia 1325 Galateola 1375 Felania 1312 Galathea 1375 Felaniellal313 Galaxura 1423 Felicia 1215 Galeomma 1327 (pt. 1) 1512 Galileia 1296 Grammatodonax 1374 Galiteuthis 1481 Grammatomya 1378 Gari 1378 Gastrana 1386 Grandaxinaea 1214 Gastranella 1359 Graneledone 1498 Gastrochaena 1405 Granicorium 1342 Geloina 1293 Granodomus 1068 Gemellima 1237 Graphonaias 1271 Gemma 1353 Genaxinus 1314 Gibbosula 1249 Graphonaias 1262 Graptacme 1196 Gitocentrum 1408 Grimalditeuthis 1475 Glabaris 1280 Grimpella 1498 Grandidieria 1247 (pt. Gregariella 1222 Glans 1290 Grimpoteuthis 1488 Glaucion 1236 Grippina 1402 Glaucoderma 1227 Glaucomya 1393 Glauconome 1393 Gyrinella 423 Glaucus 1227 Haasica 1278 Guetera 1413 Globisinum 392 Globus 1333 (pt. 1) Hadziella 204 (pt. 1) Halicardia 1428 Halicardissa 1428 Gloconome 1312 Haliphron 1500 Haliris 1428 1205 Glossocardia 1302 Glossoderma 1300 Glossus 1300 Glycilima 1215 Glycimeris 1399 Glycymeris 1213 Glyptosepia 1443 Glyptostoma 929 (pt. 2) Gnathodon 1363 Gobraeus 1378 Gomphina 1352 Gompbinella 1353 Gonatopsis 1462 Gonatus 1461 Goniaxis 1145 1) Haasiella 1267 Glebula 1270 G/0/wi/.s (pt. (pt. 2) Halonympha 1432 Hamacuna 1287 Hansenoteuthis 1487 Hapalochlaena 1497 Haplomochlia 1311 Haptochlaena 1497 Harlea 1400 Harmandia 1278 Harpax 1229, 1382 Hatasia 1409 Hecuba 1374 Heledone 1494 Helicocranchia 1483 Gonidea 1259 Gonilia 1285 Goniomactra 1369 Goodallia 1286 Goodalliopsis 1322 Gouldia 1343 Gouldiopa 1342 Gradaterebra 582 Halistrepta 1423 Hallia 1494 (pt. 1) Helonyx 1194 Hemicardia 1339 Hemicardium 1338 Hemicyclodonta 1372 Hemicyclonosta 1372 Hemicyclostera 1372 Hemidonax 1373 2) 1513 Huxley ia 1215 Hyalopecten 1230 Hemidonta 1267 Hemilastena 1263 Hemimactra 1364 Hyaloteuthis 1470 Hemimetis 1386 Hemiodon 1267 Hyaloteuthis 1472 Hemipecten 1235 Hemisepiola 1447 Hypania 1340 Hypanis 1340 Hymenoteuthis 1487 Hyperotus Hemisepion 1443 Hemisepius 1443 1413 Hypnaxis 1340 Hypogaea 1397 Hemistena 1263 Hemitapes 1354 Hypogaeoderma 1397 Hensenioteuthis 1483 Hypogella 1397 Heptapus 1500 Hypotriphora 327 Hermiome 1352 Hypotrochus 320 Hespererato 402 (pt. 1) (pt. (pt. Hyria 1278 Heteranomia 1240 Hyriana 1278 Heterocardia 1369 Hyridella 1275 Heteroclidus 1418 Hyriopsis Heterodonax 1376 Heteroglypta 1376 Hysteroconcha 1346 1256 Heteroschisma 1197 Iacra 1383 Heterosepiola 1447 Idas 1219 Heteroteuthis 1445 Idasola 1219 Hiatella 1398, 1416 Idiosepius 1448 Hiatula 1377 Idioteuthis 1475 Himantopoda 1225 M>rAea 1320 Himella 1401 Iduliana 735 Hinnites 1234 Illex (pt. Hippagus 1220, 1428 Lnparilarca 1213 Hippella 1428 Indonaia 1247 Hippopus 1341 Hirtomurex 453 2) 1469 Indopseudodon 1250 (pt. 1) Indoteuthis 1466 Histiochromius 1465 Inioteuthis Histiopsis 1464 Inversidens 1249 Histioteuthis 1464 Ioteuthion 1456 1448 Hochstetteria 1217 Iphigenia 1375 Hochstetteria 1217 Iphigenia 1428 Hochsteterina 1217 Holopholas 1407 Homala 1392 Homalina 1389 Iridea 1248, 1276 fridina 1282 Iridioteuthis 1475 fridoteuthis 1446 Homeoeodesma 1421 Hormomya 1221 Irona 1357 Horusia 1248 Isarcha 1377 Hoylea 1494 Ischadium 1221 Irus 1357 Humilaria 1355 Isocardia 1300 Humphreyia 1426 Isoconcha 1330 1) 1) 1514 Isognomon 1224 Isognomum 1225 Isogonum 1224 Labiosa 1367 Isolimea 1237 Lactemiles 1326 Isomonia 1240 Isorropodon 1 303 Lacustrina 1297 botriphora 327 Issina Labis 1223 Lacinia 1333 Laetmoteuthis 1488 (pt. 1) Laevicardium 1335 Laevicordia 1427 1330 Laevidentalium 1196 kartia 1421 Laevirostris 1248 Lajonkairea 1358 Jactellina 1391 Jacunia 732 (pt. 2) Lamelliconcha 1346 Jagonia 1319 Lamellidens 1252 Janira 1234 Lamellileda 1207 144 Japetella 1492 Lamelliger Jaronia 1248 Laminaria 1370 Jataronus 1333 Lampadioteuthis 1452 Jesonia 1290 Lamproscapha 1280 Lamprotula 1249 Lampsilis 1272 Jheringella 1279 Joannisia 1313 1 (pt. Joannisiella 1313 Lanceolaria 1258 Jouannetia 1411 Lanistes 1222 Joubinia 1496 Lanistina 1222 Joubiniteuthis 1476 Jousseaumia 1331 Lasaea 1322 Lasmigona 1265 Jousseaumiella 1331 Lasmonos 1271 Jugosus 1267 Lastena 1267 Jukesena 1353 Latemula 1424 Latiromurex 453 (pt. Latona 1374 Laubriereia 1330 Lazaria 1290 Lazariella 1290 Julia 1310 Junonia 1206 Jupiteria 1207 Kalayoldia 1209 Katadesmia 1209 Katelysia 1354 Kellia 1322 Kelliella 1298 Kelliola 1323 Kelliopsis 1330 Kellya 1322 Kellyella 1298 Kennerleya 1418 2) 1) Leachia 1477 Leda 1207 Ledella 1206 Ledina 1207 Legrandina 1 305 Leguminaia 1266 Leguminaria 1395 Leila 1280 Leiomya 1433 Kennerlia 1418 Leionucula 1202 Kidderia 1309 Leiosolenus 1223 Kuphus 1413 Leiotrochus 71 (pt. 1) 1515 Leiovirgus 1246 Limopsis 1215 Lembulus 1207 Lemiox 1274 Limosina 1298 Linga 1315 Lens 1255 Linidiella 131 (pt. 1) Lenticularia 1319 Lintellaria Lentidium 1400 Lioberus 1223 Liocardium 1335 Lioconcha 1342 Lentillaria 1319 Lepadomurex 453 (pt. 1319 1) Liocranchia 1478 Lepidocardia 1346 Lepirodes 1327 Liocyma 1353 Liodonax 1374 Lioglyphostoma 566 Leporimetis 1386 Liomya 1433 Lepidodesma 1265 Lepidoteuthis 1450 1017 Leptaxinus 1314 Lionelita 1326 Leptina 1372 Lionucula 1202 Leptodea 1271 Liotellina 1392 Leptodontoteuthis 1452 Liouvillea 1267 Leptomya 1383 Lirophora 1352 Lepton 1324 Lissarea 1216 Leptonaias 1262 Lissarcula 1216 Leptosiphon 1293 Lissopecten 1231 Leptospatha 1281 Listera 1383, 1397 Leptospisula 1365 Litharca 1211 Leptoteuthis 1473 Lestoteuthis 1461 Lithodomus 1222 Lithophaga 1222 Leucocranchia 1480 Lithophagella 1302 Leucoma 1351 Lithophagus 1222 Leucoparia 1367 Litigiellal329 Leucothea 1345 Lituina 1441 Leukoma 1351 Lituus 1441 Levanderia 1327 Lobaria 1377 Lexingtonia 1262 Loligo 1449 Libera 919 Loliolopsis 1448 (pt. 2) Libitina 1302 Loliolus 1449 Libratula 1327 Lolliguncula 1449 Ligula 1317, 1423 Loncosilla 1394 Ligumia 1272 Liguriella 1479 Longimactra 1364 Lima 1236 Lopha 1242 Lophocardium 1335 Limaria 1236 Lophosepia 1442 Limarula 1237 Lophosepion 1442 Limatulellal238 Loringella 1215 Limea 1238 Loripes 1317 Limicola 1387 Loripinus 1318 Limnoperna 1220 Limoarca 1238 Lovellia 1368 Limopsilla 1216 Loxocardium 1339 Loxoporus 1 1 94 (pt. 1) 1516 Luchuconulus 977 (pt. 2) Magaleda 1206 Lucina 1318 Magdala 1416 Lucinella 1317 Malleolus 1412 Lucinida 1317 Malletia 1204 Lucinisca 1316 Malleus 1225 Malvinasia 1329 Lucinoma 1316 Ludovicia 1310 Malvufundus 1226 Mamiconus 577 (pt. Lunarca 1213 Mancikellia 1323 Lunulicardia 1339 Mantellum 1238 Manupecten 1233 Maorimactra 1366 Lucinopsis 1358 Luteacarnea 1260 Lutetina 1308 Lutraria 1369 Maoritellina 1384 Lutricularia 1383 Lutromactra 1369 Marcia 1354 Margariona 1229 Lutrophora 1369 Margarita 1227 Luzonia 1433 Margaritana 1245 Lycoteuthis 1452 Margaritanopsis 1245 Lymnium 1257 Margaritiphora 1227 Lyonsia 1416 Mariana 695 Lyonsiella 1427 Marshalliella 1278 Lyrocardium 1335 Lyrodus 1413 Martesia 1410 Macalia 1387 Martialia 1470 (pt. Martensnaias 2) 1263 Martesiella 1410 Mastigopsis 1475 Maceris 1333 Macerophyllum 1333 Macha 1380 Machaena 1362 Mastigoteuthis 1475 Medionidus 1270 Megacardita 1289 Megadesma 1375 Megadomus 1265 Machaera 1395 Machaerodonax 1374 Macoma 1387 Macomona 1390 Megalocranchia 1480 Macridiscus 1353 Megaloteuthis 1463 Macrocallista 1346 Macrochlaena 1497 Macroctopus 1495 Macrogonaxis 1042 Macrothylacus 966 Macrotritopus 1496 Mactra 1365 Mactrella 1367 Megalonaias 1260 Megapitaria 1345 Megateuthis 1463 (pt. 2) (pt. 2) Megaxinus 1318 Megayoldia 1209 Meiocardia 1301 Melanoteuthis 1486 Melaxinaea 1214 Meleagrina 1227 Mactrinula 1367 Meleagroteuthis 1464 Mactroderma 1366 Melina 1224 Mactromeris 1364 Melliteryx 1321 Mactrotoma 1366 Madrela 1225 Mercenaria 1351 Mendicula 1319 1) 1517 Meridosinia 1349 Modiola 1220 Modiolarca 1222, 1309 Merisca 1388 Modiolaria 1222 Meroe 1347 Merope 1368 Modiolula 1221 Meropesta 1368 Afoera 1391 Mesanodon Moerella 1391 Meretrix 1347 Modiolus 1220 -1267 Molarella Mesembrisepia 1442 Mesodesma 1362 Mesonaias 1273 Mesonychoteuthis 1461 Mesopeplum 1233 Mesopleura 1379 Metabola 1371 Metadrymaeus 1038 Metaptera 1270 1 149 (pt. (pt. Monocondylaea 1279 Monocondylus 1250 Monodacna 1340 Monodonta 1264 Monodontina 1250 2) Metasepia 1443 Monoeciostrea 1242 Metis 1354, 1386 Mexicardia 1336 Monothyra 1408 Montacuta 1329 Micrabralia 1454 Montrouzieria 1382 Microcardium 1334 Microcolus 499 (pt. Moroteuthis 1460 Moroteuthopsis 1) 1018 Microcondylaea 1266 (pt. 2) Mulleria 1284 Micromactra 1367 Micromya 1272 Micromytilus 1216 Micronaias 1262 Micropyrgula 227 Microsalpinx 202 1461 Moschites 1484 Mouchezia 1463 Mulinia 1364 Microcucullaea 1212 Microhedyle 726 2) Moncetia 1281 Monia 1240 Monitilora 1318 (pt. (pt. 1) 1) Murcia 1351 Murithais 436 (pt. Musculium 1298 Musculus 1222 Mutela 1282 1) Mutelina 1282 Microteuthis 1448 Microtrypetes 582 (pt. 1) Mya 1403 Microyoldia 1205 Myalina 1402 Migranaja 1248 Mikrola 1382 Myatella 1416 Mycetopoda 1280 Milneria 1291 Mycetopodella 1281 Miltha 1317 Mimachlamys 1233 Mycetopus 1280 Myllita 1325 Minormalletia 1204 Myllitella 1325 Miocardia 1301 Myochama 1419 Miodon 1289 Myodora 1418 Miodontiscus 1289 Myoforceps Mirellia 1152 Mittrea 1312 Myomactra 1370 Myonera 1432 Myoparo 1220 Modiella 1221 Myrwa (pt. Mitriodon 1281 2) 1220 1223 1518 Myrsopsis 1354 Neoteredo 1413 Myrsus 1354 Myrtea 1317 Neoteuthis 1457 Mysea Nephritica 1263 1257 Neotrigonia 1244 Mysella 1329 Nephronaias 1262 Mysia 1358 Mysia 1312 Nepioteuthion 1454 Mytilicardita 1290 Nesis 1360 Nesonaia 1246 Nettastoma 1409 Mytilimeria 1417 Nettastomella 1409 Mytilina 13\\ Nevenulora 1318 Mytilaster 1221 Mytilocardia 1290 Newboldius 1039 Mytiloides 1311 Mytilomya 1311 Niaea \216 Nicania 1285 Mytilopsis Nitia 1248 1311 Mytilus 1223 Nodipecten 1233 Nodularia 1257 Naejidium 1448 Noetia 1213 Naia 1278 Naidea 1270 Nannomactra 1365 Nannonaia 1254 Napaeinus 836 (pt. 2) Naranio 1359 Nasus 1250 2) Noetiella 1213 Nomma 1125 (pt. Nothapalinus 888 2) (pt. 2) Notrius 1357 Notobadistes 1019 (pt. 2) Notocallista 1346 Notochlamys 1233 Nausitora 1415 Notocochlis 392 Nautilus 1436 Notocorbula 1401 Navea 1409 Notolepton 1308 Notolimea 1237 Navicula 1211 (pt. (pt. Nayadina 1267 Neaera 1431 Notomya 1420 Neaeromya 1321 Notomytilus 1216 1) Notomyrtea 1317 Nectoteuthis 1446 Notopaphia 1357 Neilo 1204 Notopeplum 534 Neilonella 1204 Notospisula 1363 Nematolampas 1452 Nemocardium 1335 Nototeredo 1413 Neobankia 1415 Neocardia 1216 Notovola 1234 Neocorbicula 1295 Nsendwea 1152 Neodiastoma 226 (pt. 1) Neofossarulus 227 (pt. 1) Neogaimardia 1309 Neogaimardia 1309 Neolepton 1308 Neopisidium 1297 Neosolen 1397 Nucinella 1215 (pt. 1) Nototodarus 1469 Novaculina 1394 (pt. Nucula 1202 Nuculana 1202 Nuculina 1215 Nuculocardia 1220 Nudiola 1221 Numella 1313 2) 1519 Nuttallia 1377 Ostrenomia 1229 Nux 1297 Nympha 1347 Ostreola 1242 Oamaruia 538 (pt. 1) Obelus 1105 (pt. 2) Ovatipsa 412 Oudardia 1391 Ovaleda 1205 Obliquaria 1268 1) Oxyperas 1365 Ozaena 1494 Obliquata 1260 Obovalis 1250 Ozoena 1494 Obovaria 1271 Obrussena 633 (pt. Owenia 1483 Oxynaia 1257 (pt. 2) Vachydesma 1347 Obtellina 1389 Pachykellya 1308 1456 Octopodoteuthis Pachynaias 1274 1457 Octopodoteuthopsis Octopus 1495 Paedophoropus 340 Ocythoe 1501 Odatelia 1263 Palamharpa 523 Palliolum 1230 Odoncinetus 1421 PaUium 1233 Oedalia 1358 Panacea 1420 Oedalina 1358 Panamicorbula 1402 Ofifadesma 1424 Pandora 1417 Okadaia 725 (pt. 2) Omala 1392 Ommastrephes 1470 Ommatostreph.es 1470 Omphaloclathrum 1349 Pandorella 1417 Onithella 33 Onychia 1458 Paphia 1355 Paphia 1362 Onychoteuthis 1459 Paphies 1362 (pt. Onykia 1458 Oopyramis 356 (pt. 1) Pandorina 1416 Pangania 997 (pt. 2) Panomya 1399 Panopea 1399 1) Paphirus 1357 (pt. Papillicardium 1339 1) Opisocardium 1339 Opisthoteuthis 1490 Opposirius 366 (pt. (pt. Papyri dea 1336 Papyrina 1367 Paracerastus 849 1) Orbiculus 1348 (pt. Paracerithium 345 Orbiculus 1319 1019 2) (pt. Paradione 1346 Orixa 1383 Paralepida 1327 Omithoteuthis 1470 Parcdlelepipedum 1212 Orobitella 1330 Orodrymaeus 1038 Oronthea 1322 Orthonymus 1260 Orthoyoldia 1209 Ortmanniana 1273 (pt. 2) Paramusium 1231 Paramya 1399 Paranoetia 1213 Parapholas 1410 Paraptera 1271 Parascala 331 (pt. Ortygia 1352 Parasepia 1442 Osteodesma 1416 Parasira 1501 Ostrea 1242 Parastarte 1353 1) 1) 1) 1520 Paratapes 1356 Periglypta 1350 Parateuthis 1466 Periplonia 1423 Parathyasira 1314 Perlamater 1227 Pardosinia 1349 Perna 1224 Peronaea 1392 Pareledone 1495 Parembola 1386 Peronidia 1392 Parilimya 1419 Perothis 1477 Parimalleus 1226 Parmaphorella 48 Perrierina 1304 (pt. 1) Pervisinum 394 (pt. 344 Paroctopus 1497 Petrasma 1210 Parreysia 1247 Petricolaria Parthenope 1327 Parvicardium 1337 Pexocodakia 1320 Parmulina 1 Parviconus 577 Petricola 1358 Phacoides 1315 1) Phacosoma 1348 Parvilucina 1315 Parvithracia 1422 (pt. Pharaonella 1392 Pharaonia 1248 Pharella 1396 Pharus 1395 Phaseolicama 1309 Phaseolus 1206 Phasmatopsis 1479 1) Parvivenus 1352 Pasiphae 1351 Patinopecten 1234 Patro 1240 Patularia 1267, 1280 Paucidentella 1 1359 Pfefferiopsis 1462 (pt. Parvitonna 430 149 (pt. 1299 2) Phasmatoteuthion 1481 Paxyodon 1278 Phaxas 1396 Pherusina 337 Pecten 1233 Philinoglossa 652 Pectinella 1230 Philippiella 1217 Pauliella (pt. Pectunculina 1215 Philippina 1417 Pectunculus 1214, 1348 Philis Pedalion 1224 Philobrya 1217 Pedum 1235 Philonexis 1501 Pegias 1264 Pellasimnia 407 1) 1) (pt. 1314 Phlyctiderma 1313 (pt. 1) Pholadidea 1409 Pelopia 1421 Pholadomya 1420 Peloriderma 1242 Pholadopsis 1411 Peloris 1242 Pholas 1408 Pholeobia 1398 Pendaloma 1423 Pene 836 (pt. 2) Phragmorisma 1421 Penicillus 1425 Phrynelima 1215 Penita 1274 Phylloda 1390 Penitella 1409 Phyllodina 1390 Pennaria 1228 Phyllonaias 1273 Peplum 1233 Phymesoda 1297 Peru 1296 Peraeonoderma 1374 Pericylindrica 1258 Pilea 1274 Physunio 1255 Pillucina 1320 2) 1521 Pilsbryoconcha 1254 Pliodon 1282 Pinctada 1227 Plurigens 1352 Pinctada 1225 Pododesmus 1241 Pinguitellina 1384 Polia 1395 Pinna 1228 Polititapes 1355 Pinnoctopus 1486 Polymesoda 1293 Pisidium 1296 Polymetis 1386 Pistris 1289 Polypus 1495 Pisum 1296 Polyschides 1194 Pilar 1345 Pompholigina 1317 Pitaria Ponderisepia 1442 1345 Pitarina 1345 Popenaias 1262 Placamen 1352 Poroleda 1207 Placenta 1241 Poromya 1430 Placopecten 1234 Poronia 1322 Portlandia 1208 Placuna 1241 Placunanomia 1241 Potamida 1245 Placunema MAX Potamomya 1402 Plagioctenium 1233 Potamophila 1375 Plagiodon 1279 Potomida 1245 Prasina 1310 Plagiola 1269 Plagiolopsis 1269 Pratulum 1335 Planctoteuthis 1472 Praxis 1311 Plandspirites 1333 Pressidens 1253 Platiris Pressodonta 1264 1282 Platydonax 1374 Primella 1298 Platynaias 1265 Prisodon 1277 Platyodon 1404 Prisodontopsis 1256 Platyschides 1194 Pristes 1323 205 Platysepia 1442 Pristigloma Plebidonax 1374 Pristiphora 1323 Plectodon 1433 Pristis Plectomerus 1260 Proagorina 1427 1 1389 Plectoteuthis 1463 Problitora 180 (pt. 1) Pleiodon 1282 Pleiorhytis 1376 Procos 1375 Prodromoteuthis 1454 Plethobasus 1261 Profischeria 1375 Pletholophus 1266 Prohyriopsis Pleurobema 1261 Prolasmidonta 1264 Pleurobranchoides 690 (pt. 2) 1255 Promachoteuthis 1450 Pleurodon 1215 Promilax 966 Pleurolucina 1316 Propeamussium 1230 (pt. 2) Pleuromeris 1289 Propecuna 1287 Pleuronaia 1260 Propehyridella 1275 Pleuronectia 1231 Propeleda 1207 Plicatula Propemelibe 733 1229 Plicoleacina 906 (pt. 2) Propescala 331 (pt. (pt. 2) 1) 1522 Prophctilora 1318 1020 Pmpilula 980 Pseudoleila 1280 (pt. Pseiidomalletia 204 Pseudomastus 836 (pt. 2) Pscudometis 1387 2) 1 Proptera 1270 Protapes 1355 Prothyasira 1314 Pscudomiltha 1318 Protohyridclla 1275 Pseudonumacha 1111 Protonucula 1204 Pscudomulleria 1284 Protothaca 1354 Pseudomutela Protunio 1254 Pscudoneacra 1432 Proxichione 1350 Proximitra 514 Proxiuber 392 282 1 Pseudoon 1271 (pt. Pseudoplccta 993 1) (pt. (pt. Pseudosacculus 399 Psammobella 1378 Pscudospatha 1281 Psammobia 1377 Psammocola 1377 Psammophila 1370 Psammosolen 1380 Pseudoxyperas 1367 Pseudunio 1245 Psilopus 1333 Psiloteredo 1411 Psammotaea 1377 Psilunio 1248 Psanimotclla 1377 Psoronaias 1261 Psammotellina 1377 Psorula 1260 Psammotrcta 1387 Psychrotcuthis Pscphidia 1353 Ptcranodon 1267 Psephis 1353 Pteria 1227 Pscudamussium 1233 Pscudanodonta 267 Ptcroctopus Pseudantalis Pterospira 531 1462 1497 Pteromeris 1289 1 1 1 96 Pseudarcopagia 1385 (pt. 1) Ptcrosyna 1265 Pseudavicula 1256 Ptcrygiotcuthis 1456 Pseuderiphyla 1286 Pterygonepion 1456 Pseudcupcra 1297 Pscudobaphia 1249 Ptychina 1314 Ptychobranchus 1268 Pseudobornclla 729 Pseudocalaxis 881 (pt. Psilopoderma 1333 377 1 2) Pseudopythina 1325 1) Psammacoma 1387 Psammosphacrita (pt. (pt. (pt. 2) Ptychoderma 1274 Ptychorhynchus 1257 2) Pscudochama 1333 Pscudochondrula 836 Pseudocorbicula 1 296 (pt. Ptychocardia 1305 2) Pullastra 1355 Pulsellum 1195 Pseudoctopus 1497 Punigapia 1381 Pseudocyrena 1293 Pupigulclla 1149 (pt. 2) Pseudodon 1250 Pupoidopsis 823 (pt. 2) Pscudodontideus 1267 Pustulosa 1260 Pseudodus 1250 Pseudoglomus 1204 Pscudogonaxis 1142 Pycnodonta Puysegeria 1308 (pt. 2) 1 242 Pyganodon 1267 Pscudokcllya 1305 Pyrgopsis Pscudolcguminaia 1266 Pyroteuthis 1477 1456 1) 2) 1523 Pythina 1325 Rivulina 1297 Pythinella 1329 Roccllaria 1405 Roihcjorlia 1329 Quadrani 1388 Roche fort ina 1329 Quadmla 1259 Roche fortula 1325 Questimya 1431 Quidnipagus 1389 Rondeletia 1447 Quincuncina 1259, 1260 Rondelctiola 1447 Radiatula 1247 Rotundaria 1261 Ronibergia 1385 Russia 1444 Radula 1 Rudicardium 1337 237 Rudi tapes 1355 Rudlania 1247 Racta 1368 Ractella 1368 Raetina 1 Ruganodontites 1280 368 Rugifero 1264 R dieta 1400 Ramoliva 506 (pt. Rupellaha 1359 1) Rangia 1363 Rupicola 1421 Rangianella 1363 Rytia 1248 Rangitotoa 762 Rasama 984 (pt. (pt. 2) Saccella 1207 2) Rastellum 1242 Saginafusus 497 Rcctidcns 1251 Salacia 1352 Renatus 1248 Salaputium 1286 Reneus 1248 Salmacoma 1387 Reniella 1225 Samarangia 1344 Resania 1370 Sandalops 1483 (pt. Rcticulatus 1263 Sanguinolaria 1377 Retroteuthis 1487 Sarcpta 1205 Rexithaerus 1387 Saturnia 1204 Rhabdus 11% Rhectocyma 1285 Rhinoclama 1433 Rhinomya 1433 Savignyarca 1212 Rhipidodonta 1276 Sayunio 1263 Rhomalea 1355 Scabies 1256 Rhomboidella 1220 RhomhoiiL>s 398 Scacchia 1321 Rhomboscpia 1442 Rhombosepion 1442 Rhomhunio 1248 Rhombuniopsis 1248 Scaeofax 469 Scalaricardita Rhombus 1398 Scalenaria 1261 Rhopalogonium 1020 (pt. 2) Rhysotina 999 (pt. 2) Scalenilla 1275 Rhytidoconcha 1079 Scambulal287 Saxicava 1 398 Saxicavella 1399 Saxidomus 1346 Scaeochlamys 1233 1 (pt. 1) Scaeoleda 1207 Scaeurgus 1496 (pt. 2) 1 289 Scalpomactra 1364 Rictocyma 1285 Scapharca 1213 Ringicardium 1337 Scaphula 1211 1) 1524 Schepmania 1249 Setaliris Schistodesmus 1255 Silenia 1431 Schizocleithrum 1252 Silicula Schizodentalium 1197 Siliqua 1395 Schizodesma 1365 Siliquaria 1379 Schizothaerus 1369 Similipecten 1230 Scintilla 1326 1327 1326 Scissodesma 1365 Simpsonella 1254 Simpson ia 1256 Simpsoniconcha 1265 Scissula 1391 Sinodia 1348 Scintillula Scioberetia 1332 1021 1208 Simomactra 1367 Simonaias 1262 Simpsonaias 1265 Scintillona 1326 Scintillorbis 1428 Scissula 1209 Sinomytilus Scissulina 1393 Sinonovacula 1395 Scobina 1407 Sintoxia 1259 Scobinopholas 1407 Siphonentalis 1195 1224 Scrobicularia 1383 Siphonodentalium Scrobiculina 1390 Siphonodontum 1195 Solamen 1220 Solanderina 1347 Solatisonax 272 (pt. 1) Scutarcopagia 1386 Scutigera 1410 Scyphomya 1410 Scyphus 826 (pt. 2) Semelangulus 1381 Solecardia 1326 Solecurtellus 1379 Semelartemis 1349 Solecurtoides 1395 Semele 1380 Semelina 1381 Solecurtus 1380 Semierycina 1321 Solemya 1210 Solemyarina 1210 Solen 1397 Solena 1397 Solenaia 1268 Solenarius 1397 Semipecten 1235 Semirossia 1444 Senectidens 1215 Senilial213 Sepia 1442 Soleilletia 1295 Sepiadarium 1444 Sepidium \AA1 Solenella 1204 Sepiella 1443 Solenocurtus 1380 Solenocurtellus 1379 Sepietta 1447 Solenomya 1210 Sepiola 1447 Solenotellina 1377 Sepiolina 1446 Soletellina \311 Sepioloidea 1443 Solitosepia 1442 Sepioteuthis 1449 Septifer 1221 Souleyetia 1383 Spaniodon 1330 Spatha 1282 Serratisphaerium 1297 Spathella 1281 Septaria 1413 1 1 Serridens 1323 Spathidosepia 1442 Serripes 1337 Spathiodosepion 1442 Serrula 1374 Spathophora 1433 95 " 1525 Spathopsis 1252, 1281 Subcultellus 1396 Spathoteredo 1413 Suborbiculus 1250 Spengleria 1404 Subtagelus 1379 Sphaerella 1313 Subtentus 1268 Sphaeriastrum 1297 Sulcastrum 1297 Sphaerium 1297 Sphaerumbonella 1323 Sphenalia 1329 Sphenia 1402 Sphenonaias 1262 Spinosipella 1428 Sulcularia 1 265 Sundavitrina 956 (pt. 2) Sunemeroe 1347 Sunetta 1347 Sunettina 1347 Sunettina 1347 Sutura 1224 Spinula 1207 Spiroscutalus 1036 (pt. 2) Sydlorina 1320 Symmorphomactra 1364 Symphynota 1270 Simla 1441 Spisula 1364 Spisulina 1364 Symplectoteuthis 1471 Spixoconcha 1279 Synapticola 1331 Spondervilia 1361 Syndesmia 1383 Syndosmya 1383 Syntomodrillia 547 Spondylus 1236 Sportella 1307 Stalagmium 1220 Standella 1368 Stankovicia 227 (pt. Starkeyna 90 (pt. Tagalus 1379 1) Tagelus 1379 1) Stauroteuthis 1488 Talabrica 1286 Stavelia 1221 Talochlamys 1233 Steatodryas 1085 (pt. 2) Talona 1408 Talonella 1409 Steenstrupia 1463 Talostolida 412 Steenstrupiola 1458 Steironepion 567 (pt. 1) Stempelleria 1217 (pt. Tanea 392 (pt. Taningia 1456 1) Stenabralia 1453 Tankaia 1473 Stephanopus 1210 Tanysiphon 1394 Stqphanoteuthis 1445 Stirpulina 1425 Taonidium 1481 Taonius 1480 Tapes 1356 Taphrospira 985 Stoloteuthis 1446 Taria 1362 Streptopinna 1228 Tawera 1352 Striata 1260 Telemactra 1366 Sthenoteuthis 1470 Stigmatoteuthis 1463 1383 Striosubulina 882 Striotellina (pt. 2) Teleonychoteuthis 1459 1385 Strigillina 1) Tamsiella 1279 Stempellia 1217 Strigilla (pt. Syntoxia 1259 1389 Teleoteuthis 1458 (pt. 2) Tellidora 1388 Tellimya 1322 Strophitus 1267 Tellina 1392 Styganodon 1280 Tellinangulus 1391 1) 1526 Tellinella 1392 Tinctora 1345 Tellinides 1392 Tindaria 1203 Tellinimactra 1388 Tindariopsis 1204 Tellinungula 1387 Tivela 1347 Temnoconcha 1387 Todarodes 1470 Tentidonax 1374 Todaropsis 1469 Tenuisepia 1443 Teramachia 527 Tomala 1400 (pt. 1) Torulosa 1274 Teredops 1413 Teredora 1412 Tottenia 1353 Toxelasma 1271 Teredothyra 1413 Toxeuma 1479 Terentia 1357 Toxolasma 1271 Teretileda 1207 Tracheloteuthis 1467 Teretoctopus 1498 Tesseracme 1196 Trachyochridia 227 Tetragonostea 1416 Transennella 1346 Trachycardium 1336 (pt. Tetraplodon 1276 Trapezium 1290, 1302 Tetronychoteuthis 1458 Trapezoideus 1251 Teuthidiscus 1491 Tremoctopus 1501 Tresus 1369 Trichomusculus 1222 Teuthis 1450 1022 Toroteuthis 1472 Teredo 1412 Teuthowenia 1483 Textrix 1356 Thaumatolampas 1452 Thaumeledone 1499 Thecalia 1290 Thecodonta 1323 Theliderma 1260 Thelidioteuthis 1455 Thelxinovum 412 (pt. 1) Theora 1382 Thericium 318 (pt. 1) Thestyleda 1207 Trichomya 1221 Tridacna 1340 Tridonta 1285 Trigona \3A1 Trigonella 1347, 1365 Trigoniocardia 1339 Trigonocaelia 1215 Trigonodon 1250 Trigonulina 1428 Triodonta 1289 Triomphalia 1411 Thetis 1286, 1430 Thovana 1408 Triplodon 1278 Thracia 1421 Triquetra 1278, 1352 Tripterotyphis 442 Thracidora 1427 Triquetrana 1278 Thraciopsis 1422 Trisidos 1212 Thy as 1211 Trisis Thyasira 1314 Tritaxeopus 1495 (pt. 1212 Thyatira 1314 Tritogonia 1260 Thyella 1382 Trivellona 402 Thyreopsis 1327 Tropidocardium 1337 Thysanoteuthis 1472 Tropidocyclas 1297 Tichogonia 1310 Tropidomya 1433 Tropidophora 1433 Truncacila 1203 Tigammona 1349 Timoclea 1351 1) (pt. 1) 1) 1527 Truncilla 1270 Venatomya 1403 Truncillopsis 1274 Venericardia 1289 Trutina 1417 Veneriglossa 1299 Tuangia 1354 Tubidentalium 1195 Venerupis 1354 Tuceta 1214 Venus 1349 Ventricola 1349 Tucetona 1214 Venusta 1273 Tudes 1225 Tugonella 1403 Venustaconcha 1273 Vepricardium 1336 Tugonia 1403 Turlosia 1407 Veprichlamys 1233 Turquetia 1331 Verania 1456 Veremolpa 1351 Turtonia 1305 Verpa 1425 1467 Tychocardia 1300 Verrilliola Tyleria 1421 Verrilliteuthis Tyndaria 1203 Versipella 1215 Typhlochiton 33 (pt. 1) 1480 Vertambitus 1428 Verticipronus 1216 Ungoteredo 1413 Verticordia 1428 Ungulina 1313 Vertisphaera 1428 Vesicomya 1299 Uniandra 1251 Villorita Uni 1257 Uniomerus 1262 1294 Villosa 1273 Unionella 1255 Vimentum 1289 Unionium 1227 Virgus 1246 Uniopsis 1264 Vitreledonella 1494 Uperotus 1413 Vola 1234 Utterbackia 1267 Volsella 1221 Utterbackiana 1267 Vulcanomya 1433 Vulsella 1225 Vaferichiton 16 (pt. 1) Vulsella 1224 Vagina 1397 Vampyroteuthis 1486 Wallucinal318 Wamea 1426 Watasea 1454 Vancleaveia 175 Watasella 1487 Valbyteuthis 1468 Valdemaria 1475 (pt. 1) Vanganella 1370 Varicorbula 1401 Varotoga 1326 Watasenia 1454 Webbia 1 147 (pt. 2) Woodia 1285 Vasconiella 1327 Vasticardium 1336 Xerarionta 1097 Vaticinaria 1318 Xestopyrgula 227 Velargillal358 Xylophaga 1408 Xylophagus 1409 Xylotomea 1408 Xylotrya 1408 Veletuceta 1214 Velodona 1495 Velorita 1294 Velunio 1255 (pt. 2) (pt. 1) 1528 Zemysia 1312 Zemysina 1312 Yoldial209 Yoldiella 1208 r, , • >*>, Zachsial414 Zairia 1248 Zanassarina 482 Zearcopagia (pt. 1385 1223 1325 1) Zenatia 1371 Zirfaea 1407 Zoe n22 Zopoteredo 1412 Zozia 1379 Zucleica 1351 Zelithophaga Zygaenopsis Zemyllita Zygocranchia 1477 1477 PART 4 Comparative Morphology/Phylogeny Geographical Distribution 1531 Fundamentals of the Natural System of the Mollusks The to the task of the natural system is to give expression, as far as possible, of the animals. These relationships can be inter-relationships determined only on the basis of comparative morphology and anatomy; however there are innumerable species which are known only from their and with these we must try to determine their position in the system by a comparison of their shells alone. This will, in many cases, shells, provide the correct when result, which they can be related to position has been established. show sufficient characters by known species, whose systematic the shells the Of course at various times, species have been described, which are so isolated that they were placed genera, and exists whose relationships have not been recognized. A in separate similar case with fossils, which also, by a comparison with shells of living species can, with more or less certainty, be allocated in the system; as a rule, the uncertainty increases with geological age. The shell thus an exceptionally important, but not the only, is character for the system of the mollusks. Phylogenetically the shell is of great importance, because the molluscan type has originated also through its acquisition. In conjunction with the shell, the musculature could strengthen and give the body the characteristic thick-set form, through which the mollusks differentiate themselves from the worms. In the long evolutionary series of snails and cephalopods — margins — has become reduced in the mantle it whenever the shell most cases as a result of being overgrown by remains almost always demonstrable in the ontogenetic development. The shell mollusks. parts of the loricates is essentially different The immediately recognizable character lying musculature. from is its that of all other division into 8 one behind the other and joined with one another by It must further be emphasized that the shell as a whole directly overlies not only the visceral mass, but also the head, without forming a mantle margin. Also very remarkable is the permeation of the by strand-shaped continuations of the epithelium lying under the shell and along its margin; these "aesthetes" provided with conchiolin caps on the surface, are most probably equivalent with the epithelial packets of the perinotum, and are derived from the latter with the shell formation of the calcified shell, on which the scales have become Accordingly, the formation of aesthetes is a basis for the reduced. assumption that the shell of loricates has originated by calcification of the dorsal culticula impregnated with calcareous scales, which, like the aesthetes is absent in other mollusks. One can assume that, initially at the insertions of the muscles thin calcareous platelets were formed, 1532 which fused together 1024 in dorsum forming transverse the center of the bands, while the two end pieces became rounded. For the attachment of the gradually strengthened connecting muscles, at the anterior margins of the still 2nd—8th pieces, the apophyses developed, which is Lepidopleurus are wide apart from one another; although already small and fairly in Hanleya and Hemiarthrum they are considerably enlarged and laterally extend to the posterior corners. Correspondingly, the musculature here become considerably has already not the basis for the development of incisions at the margins, that this is but, rather that they result In Lepidopleurus, these and a and one can conclude strengthened, lateral part. In of the posterior from a different arrangement of the aesthetes. permeate the median part between the apophyses Hanleya, the In reflection. latter is fairly narrow and lies in front Tonicella and Lepidochiton, this field is divided into a posterior band situated in front of the reflection, and an anterior band, and the intervening unpermeated field forms a process at which accordingly the margin, by an is separated from the anterior apophysis The margins of incision. the two end pieces have similarly acquired incisions. In the loricate series, the insertion in their size 1st piece is number of and in the number of margins show great diversity, both incisions. The anterior margin of the smooth in Hanleya and Hemiarthrum, but has a variable incisions in several groups; in other groups their number is constant, there being 8 in mopaliids, 5 in acanthochitonines, and 3 in Cryptoplax. On the middle pieces only one incision developed on either side, is most cases in but in various groups (Callochitoninae, Stenoradsia, Ischnoradsia, Anisoradsia, Stenochiton, Rhombochiton, Radsia) there are 2 to 4 incisions on either side. In some groups the posteriormost shell part has undergone a shortening of the posterior part, along with a narrowing of the posterior insertion margin and a reduction of the incisions, occasionally with the formation of a sinus; these groups belong to various families (Mopaliidae, Acanthochitoninae, Ischnochitonidae, and Chitonidae), therefore this character is not a sign of relationship. The side, to insertion margins sometimes show radial furrows which there can be corresponding small nicks condition is in on the upper at the margin; this most cases considered as the principal character of the family Chitonidae, although the margins are also furrowed in acanthochitonines, and especially in Eudoxochiton, as well as in ischnochitonids such as some some Chaetopleura fulva (Wood), Ischnochiton nigrovirens (Blainville), Lepidozona, Lorica, and Loricella. The apophyses on the anterior margins of the 7 posterior shell parts, which are originally small and separated by a broad interspace, occasionally 1533 extend up to the middle, where they collide, as in Nuttalochiton and callochitonines. Frequently the connecting margin only narrow, and is is occasionally separated from the apophysis on either side by an incision, in some groups also with several incisions, as in Lepidozona, in Chiton, Enoplochiton, Mesotomura, and Tonicia; on the other hand, such incisions Squamopleura and Acanthopleura. are lacking in In Schizochiton, in part there are incisions on the individual pieces, in part they are missing. The pores of the median area between the apophyses, in most cases distinct primitive in 1025 when when can disappear loricates, apophyses are united; the the connecting part has incisions, these as a rule correspond to rows of pores, similar to the case of pores corresponding of sometimes the rows lateral incisions; the latter are to also overlain by an internal deposition. Whereas the insertion margins are still undeveloped in Lepidopleurus, they have reached enormous extension especially in Katharina, Amicula, Cryptoconchus, Choriplax, and Cryptochiton, however, the tegumentum has become increasingly small and become finally completely reduced, so that in Cryptochiton the aesthetes have also disappeared. It was natural to compare the structure of the loricate shell with that of other mollusks, then the tegmentum would correspond which likewise grows only at the margins and is to the "ostracum" covered by a periostracum, while the hypostracum of the snails and bivalves would be homologized not only with the hypostracum but also with the articulamentum, because it has probably originated from the hypostracum. Nevertheless, not only in lepidopleurids but also in higher forms, the layers are not so sharply separated, and in addition, the entire structure cannot assume a definite homology. completely covered hypostracum, the Philinidae, shell new is Whereas so different that one in Cryptochiton the consists only of the articulamentum shell of certain snails, such as and the Lamellariinae, Pieurobranchinae, has retained the ostracum along with the periostracum; moreover, the ostracum is never surpassed by the hypostracum. The external sculpture of the loricate shell originally consists of minute warts, which correspond to aesthetes and which often form rows on the end pieces and the rows on the median that the surface areas. lateral areas and parallel Such warts are sometimes becoming so weak appears smooth, often there are various sculptures, such as ridges or furrows or larger warts, have little effect radial longitudinal which in secondary most cases on the arrangement of the aesthetes, although occasionally these can be aggregated on the projecting places and can be reduced between them. In Lepidozona the median areas have longitudinal rows of small tubercles with the intervening spaces having minute pits, and 1534 under the ribs of the lateral areas canal-like spaces with lateral openings can be visible; in Lorica, on the outer side of the small folds on the areas, there can median be one row of perforations each and below the lateral areas there are fine canals, which open at the anterior and lateral margins. The shell of the remaining mollusks (concha) is laid down in one piece, as a dermis without any indication of scales or needles corresponding to those 1026 of loricates. It is highly variable in form, but is nearly always composed of the ostracum, the outer layer, covered by a more or less strong periostracum, and the inner hypostracum, which, along the margin, is always surpassed by the ostracum. The primitive concha has nacreous structure. Its phyletically first anlage must be visualized as a flat cap, directly overlying the visceral mass but leaving the head free. Its anterior and lateral margins do not overlie the body mass, but project freely, borne by a membranous expansion which is posteriorly produced into two symmetrical points, between which opens the rectum. The shell of Conchifera can be derived from such a primitive concha. In snails, the shell very early became considerably deep and at the same time spirally coiled. Along with the enclosed visceral mass it acquired such a weight and such a form that in its original condition it could no longer be carried by the crawling animal, and hence had to be turned around so In this way that- the opening was displaced forward. a shell form arose similar to that found in the still-living pleurotomariids, although already this group has given rise on the one hand and on the other hand to disk-shaped addition, the series slit of holes. to high-turreted shells. In could close itself at the end, thus forming a hole or a By a rapid expansion of the whorls, the shell acquired a very wide aperture, such as that found in haliotids; the series of holes is similar to that in the fossil genus Polytremaria. Proceeding further in a similar direction, the bilaterally symmetrical shells of fissurellids and docoglossans arose. A reduction of the shell flattening the gill slit could take place mainly as a result of chamber or reduction of the right gill; the sinuses or some higher groups of homologous with the slit of indentations of the apertural margin, developed in snails (Janthina, Turridae, Terebra), are not pleurotomariids. The embryonic subsequent whorls, is shell, in frequently sculptured differently from the most cases retained, but is occasionally cast off, sometimes along with a part of the subsequent whorls, especially turreted shells, in which the whorls, whereupon the shell visceral sack is is sealed in high- withdrawn from the by a newly formed wall. initial 1535 The whorls of the from one another, and shell are very rarely separated such forms, like Blaesospira (Fig. 110), Balambania, Vermetidae, Caecidae, Scala species, Lyocyclus, Camptoceras, are not primitive but are derived from normal groups with contiguous whorls; sometimes only a part of the last whorl has become separated. In such shells, the free part must naturally have a continuous apertural margin, whereas that part of the apertural margin which adjoins the penultimate whorl often does not project freely, but most cases indicated only by a callous deposition. is in Umbilicate shells are in most cases probably more primitive than nonumbilicate ones. The form of the aperture ovate, in higher groups occasionally it originally roundish or is becomes long and narrow, the whorls largely or completely surrounding each another. be narrowed by folds or Whereas the not On the columellar and sometimes also on the outer apertural margin, the aperture can side, shells show very teeth, which are developed striking sculpture, rings, also possess in various groups. of opisthobranchs and pulmonates in most cases do more or many prosobranchs, besides ribs and less large spines and bulges; such forms of scultpure partly serve for strengthening the external wall and partly for protection, and have developed in various groups. margin of species of Strombus and to the peculiar type not have a sinus certain it The expanded apertural processes in Pterocera are related of locomotion. The aperture of primitive snails does at the columellar end and lacks a more less long groove- shaped process. Nevertheless relationship; its presence alone does not indicate its has arisen independently in several series, such as in melaniids and cerithiids, in aporrhaids and strombids, cypraeaceans and doliaceans, as well as in the stenoglossans, where it in is sometimes very long, for which reason the siphonostomatous snails cannot be put together as a homogeneous group. may be elevated some prosobranchs In contrast to the very high-turreted shells, the spire 1027 only slightly or not at all, as is the case in (cypraeaceans and certain marginellids), but especially in several Cephalaspidea. In other groups, the spire has become so greatly reduced that a this cap or bowl-shaped shell with very wide aperture has developed; form of shell has also always developed secondarily from a spiral shell. Among the prosobranchs a complete reduction of the shell has taken place only in Titiscania, in which trace, .still it has been lost without leaving any and the pterotracheids, which are close to the possess a thin shell. The lamellariids show edge overgrowing the very wide-apertured, all spiral carinariids, which stages of the mantle or cap-shaped shell, giving rise to a mantle edge which has some similarity with the perinotum of loricates, although without being homologous with the 1536 A latter. similar event has taken place in some Cephalaspidea, as in Cryptophthalminae, runcinids, aplysiids, and pleurobranchids, in which the shell eventually completely disappeared. This has happeneed similarly groups of oncidiids and soleoliferans, as well as in the philomycids in the and Cystopelta, whereas other slugs in a more or less distinct shell rudiment has persisted below the skin (Athoracophoridae, Arionidae Limacidae, Trigonochlamydidae, and Aperidae). Also completely shellPhilinoglossidae, the are less the Pterota (gymnosomatous pteropods), several sacoglossans, as well as the long series of nudibranchs. The operculum, present in many prosobranchs, is attached on dorsum of the foot, hence behind the shell. posterior part of the form original is that of a the Its with several narrow whorls, with a central spiral nucleus and circular outline, corresponding to the nearly circular shell This type of operculum aperture. is present in the pleurotomariids, and trochids, also of most cyclophorids, of valvatids, and potamidids. When the form of the shell aperture undergoes scissurellids, turritellids, change and becomes ovate or even longer and narrower, the nucleus of the operculum becomes more or and growth either takes less eccentric place spirally with a few, rapidly enlarging whorls, or concentrically. In some it is with families the operculum shows considerable sometimes cartilaginous or an external variation; in cyclophorids calcified, in pomatiasids in calcareous layer, and sometimes has sometimes only a few, or only the last whorl is recognizable; naticids only the genus Natica has a calcareous operculum. turbinids, the Liotiinae most cases many whorls, among Among the have opercula with several narrow whorls, which have in Liotia a row of calcareous granulations, in Molleria and Leptothyra a continuous calcareous layer; in Turbininae and Phasianellinae the calcareous operculum is relatively thick, externally in most cases without indication of the whorls that are visible on the inner side. In operculum neritids the and an contrast, it helicinids it is calcified, spiral with rapidly enlarging whorls, internal process at the nucleus, similar to that in hydrocenids, in is is very peculiar in neritopsids (Fig. 55). The operculum of the rather variable, it is horny only in Pseudhelicina, otherwise has a more or less strong calcareous deposition; the roundish operculum of Ceratodiscus has nonspiral growth. In general, the higher prosobranchs in most cases have opercula with terminal or marginal nuclei, from which the direction of growth proceeds 1028 mainly straight or only slightly curved. In several groups the operculum has completely disappeared, mainly in shells with very wide apertures, into which the animals cannot shells with Among retract with incurved foot, but also in narrow apertures, such as the cypraeaceans and the marginellids. opisthobranchs, the operculum is still retained only in the 1537 actaeonids and spiratellids, and in all others it among pulmonates only in the amphibolids, lost. is The shell of bivalves has evolved from the primitive concha in a manner completely different from the snails. The repartition, indicated in the zeugobranchs by the has in bivalves proceeded to a division into slit, An 2 valves joined only by the ligament. happened, the median line elevation of the shell has never on the contrary, is, straight or only curved. With the bipartition, each half acquired its enable growth along the long median In order to own which the two line, at move valves were originally united, the two centers had to one another, giving moderately center of growth. apart from hinge plates, the margins of which bear the rise to hinge teeth and on the underside of which the foot muscles attach. both sides, mantle lobes and the shell the On valves are considerably broadened, so that they completely enclosed the animal along with the likewise broadened gills. Because the division of the shell into two halves is to be considered from as a secondary process, the hinge margins correspondingly differ the remaining margins of the bivalve shell and their teeth are not homologous with the marginal teeth. Originally the shell straight hinge margins, teeth fitting into pits may have been and low, with rather broad which were joined together by numerous minute on the opposite side; the ligament was situated over more or less far in most cases rounded, the dorsum and the the hinge plates and between the umbones, extending posteriorly and anteriorly. more compressed and However, the bivalve view in lateral it is shell is hinge margins narrow. This has already happened in the series of the taxodonts; in limopsids, the number of hinge teeth decreases and in' the genera Hochstetterina, Adacnarca, and Philobrya, the hinge margin shows only fine transverse grooves, but not teeth. These are as a small animals, the small mytilids Idasola and Dacrydium also finely rule show such grooved hinge margins. The anisomyarians do not possess any of the taxodont hinge margin most cases equivalent at all toothless, occasionally secondary tooth developments have arisen, of teeth, their is in which those of Plicatula and Spondylus are the most strongly developed. The hinge margin (cf. Figs. is straight, occasionally of considerable 799 and 800), often only short. The ligament when the umbones are situated near the middle; it umbones have moved toward the anterior end. the thickenings are developed in is length amphidetic opisthodetic when Several cartilagenous Crenatula and Pedalion, cases only one, as in the pectinaceans and ostreaceans. shell is in most other The embryonic along the hinge margin shows fine transverse grooves the phyletic significance of which seems doubtful. — 1538 In comparing the hinge of the trigoniids with will hardly be inclined to that of taxodonts, one homologize the large grooved teeth with the single small teeth of the latter, but will see them as secondary thickenings of the hinge margin. The homology of the teeth of Iridina with those of taxodonts completely out of the question, they have arisen secondarily is after the schizodont teeth Although 1029 denticles in were reduced. some taxodonts, the anteriormost and posteriormost can be very obliquely positioned, so that they are directed almost or completely parallel to the margin, they cannot be homologized with the lamelliform lateral teeth of heterodonts, but should be considered as secondary structures, The main grooves. which are occasionally provided with transverse teeth can taxodonts, but of these too be rather similar to the median teeth of it can be assumed that they have arisen secondarily as arch-shaped lamellae alternating in the two valves around a central tooth of the right valve; from these have developed the anterior and posterior main teeth; the central tooth is often reduced. In general, the hinge margin of the heterodonts increasingly undergoes a shortening, the lateral lamellae are frequently reduced. posterior to the umbones and The ligament always lies often sinks between the teeth, occasionally causing a reduction of certain posterior teeth. In the Adapedonta the reduction of the hinge margin has proceeded have a tendency toward reduction, whereas still further; the lateral main teeth lamellae are entirely Adesmacea not only the hinge margin but also become completely reduced, so that the two valves are joined together only by the musculture. lacking. Finally, in the the ligament have In a similar fashion as in bivalves, the shell of scaphopods can be derived from the primitive concha, but without bipartition; as in some bivalves, the mantle margins are ventrally fused with each other and with the ventral margins of the shell, so that was at more or it became an posteriorly open tube, which first extended less thin structure. to itself into a long, anteriorly and only moderately long, and then The shell is thus be considered not as turreted but as elongated. On the other hand, the shell of primitive cephalopods has turreted in bilateral symmetry, which became possible by a mode of life. become a similar fashion as in snails, but with the retention of A shift to the characteristic feature is the formation as a rule pierced by a more or less swimming of septa, which are wide siphuncle. The endoceratids elongated cylindrical forms with a large siphon divided by funnel-shaped diaphragms — were placed by Spath at the beginning; from these on the one hand the Nautiloidea are said to be descended, on the other hand orthoceratits, and from the latter the Belemnoidea and further the Recent dibranchiates. The large group with an external shell has become extinct, — 1539 with the exception of the few Nautilus species, their shell dibranchiates, only the shell of Spirula, with regular septa^pierced by a Among by the posterior part of the body, and seems the sepiids its enclosure within its The ventral inward coil. be very different, which to with that of similarity small size, its the calcareous nature and the its shows siphuncle, nautilids, but significantly differs with is spiral, simple, anteriorly concave septa and rather thin siphuncle. is still of shell calcified, but has acquired a completely different form due to the special displacement of the thin septa. In the majority of decapods, wherever the shell has not been lost, such as the sepiadriids and idiosepiids, and without trace of septa; is it uncalcified, elastic, can hardly be considered an this "gladius" equivalent of the original calcareous shell, but as secondary proostracum, 1030 whereas the chambered cavity (phragmocone), situated end, has disappeared. Among the posterior at the cirrate octopods, only Vampyroteuthis some has a thin leaf-shaped shell rudiment, which presents with the gladius of decapods, otherwise in it or brace-shaped fin support. In the Incirrata, a shell rudiment detectable; the shell in the females of structure, which is not fused with the similarity most cases forms a saddle Argonauta species body and is is hardly a secondary is by no means equivalent of Nautilus and ammonites. to the shell Like the form of the shells, its structure must also be taken into consideration for systematic purposes, but this must be done with caution. Boggild, for instance, states that the shells in so some among anisomyarian Bivalvia families are quite uniform, whereas in others they are variable that the structures Among have no systematic value. the nuculaceans, Boggild considers the condition in Leda and Yoldia species to be the most primitive, which presents no nacreous layer but where the shell is homogeneous or very indistinctly prismatic; Nucula (Lionucula) from the Eocene, the of very fine crossed lamellae; quite special Nucula in formation of radial trabeculae. In arcids the shell whose ostracum homogeneous or consists In s. s. is largely consists crossed lamellae. The structure of the schizodont shells nacreous layer. one species of in entire shell (?ostracum) consists is of very uniform, of an outer prismatic layer and an inner mytilids, an very thin, often external, indistinctly prismatic layer and an inner, nacreous, aragonitic layer are differentiated. in calcitic, most cases The Pteriacea have an ostracum consisting entirely of prisms and a nacreous hypostracum. differentiation in the structure species of the of the two valves Propeamussium and Anomia. In the is noticeable in shells A some of heterodonts crossed lamellae are in most cases recognizable. The shells of the primitive snails (pleurotomariids, haliotids, and trochids) have distinct nacreous structure, but already the fissurellids and 1540 among docoglossans have a different structure, and also we the trochaceans find smaller or larger groups {Fossarina, Skeneinae, Cyclostrematidae, and most Phasianellinae) without nacre. The neritaceans and snails have differently formed The shell of Nautilus is shells, all higher often with crossed lamellae. nacreous like that in Pleurotomaria, the septa forming the major part of the hypostracum; the shell of Spirula consists of fairly regular prisms, the septa of nacre. The mantle of conchaceans, which in its origins which anteriorly and laterally expanded lobe-shaped, and lobes are is of the slit shell margins; not fused with the head; the two posterior them so that between shell. In snails, the twisted to the right and the cleft is a cleft lies mantle and the shell are displaced anteriorly. The lobes then over the anterior part of the body and form a cavity which anteriorly open. closed. In to lacking in the loricates, should narrow, posteriorly on either side is separated by the anus, corresponding to a lie is be regarded as a fold on the lower side of the By fusing of the lobes with each other, the cleft some groups of higher snails the mantle is is is then produced anteriorly form a shorter or longer groove-shaped process. The two mantle lobes of bivalves are originally completely separated from one another, although in various 1 03 1 groups a more or less extensive fusion of the margins takes place along with the formation of sometimes short, sometimes very long, tubes for the in-current and out-current of water. arcids, and trigoniids, also in some unionaceans, In anisomyarians, the mantle has remained open, also in some nucluaceans, whereas most genera of the malletiids and ledids have formed siphons, and are fused with Solenomya the ventral margins in one another. The mantle of bivalves encloses a space which contains the entire animal, especially the foot is similar to the condition in the scaphopods, in is open anteriorly and whereas posteriorly, and the gills. This which the mantle cavity in the cephalopods it forms a posteriorly closed sack, which encloses the gills and covers most of the funnel-shaped foot. The mantle edges in snails are rarely beset with tentacles (Patellacea), but more frequently in bivalves, among developed at the current siphon; eye-like developed in some arcaceans and the siphoniates they are mainly organs of various structure are pectinids as well as on the siphons of a few cardiids. In some groups of edge extends more or snails with ear- or less subgenus Emarginella and bowl-shaped shells, the widely over the surface of the mantle shell, as in the and cypraeids, opisthobranchs in Phanerophthalmus, Philine, Gastropteron, aplysiids, and pleurobranchids; in some of these groups the shell is completely enclosed, and can then in pirulids, and in Fissurellidea, marginellids, among lamellariids, the * tend toward reduction; this among which completely is Among lost the shell. some pulmonate groups, similar also in the oncidiaceans, soleoliferans, bivalves, it is and philomycids have only in galeommatines and chlamydoconchins as well as in some montacutids partly or completely covered by the mantle. Among dibranchiate the cephalopods, it belemnites or similar forms that the shell was and that the shell is was probably in the overgrown, grasped, first completely enclosed by the mantle lobes; later 1541 thereby it first acquired the function of an internal skeleton, but in animals with short and massive body forms was completely it lost. one compares such a form as Lamellaha with loricates such as Cryptochiton, at a cursory glance the mantle of the former can appear to If be a homologue of the body edge of the latter, but a closer inspection reveals the impossibility of such a homologization. The mantle of the snails has the task of bringing about growth of the whereas the perinotum of loricates has nothing to do with shell growth, because this takes place only from a small edge beginning of the perinotum, whereas true mantle is at shell the dorsal absent. A very important difference exists in the fact that the perinotum attaches sides of the head, anteriorly at the covers the fused with gill it. If whereas the mantle of the snails cavity and often also the head dorsally, without being such characteristically differentiated forms as Lamellaria and Cryptochiton are compared with one another, without taking into consideration forms which are intermediate between them, one can get completely wrong results. The perinotum musculature, and is a is more or less strong ring-fold calcareous bodies; by an edge the upper side is fold at with separated from the lower side and the inner boundary of the latter forms a 1032 filled covered by a strong cuticula and variously formed more or less distinct which the cuticula ends. The calcareous bodies on the upper and lower sides are originally not very different, they are mainly minute scales, them which on the upper side are often ribbed, where scattered among are small cylindrical bodies in most cases in small groups; similar structures are located at the edge. The mopallids and cryptoplacids, on the upper side there are in most cases rather small needle- or club-shaped bodies and bristles with a small terminal spine or bundles of longer needles, the scales on the lower side are strikingly enlarged in more or club-like less large scales Craspedochiton. In Ischnochiton and Chiton of the upper side are placed so densely, that the bodies are restricted to the margin, whereas the lower side Most highly differentiated are the spines of Acanthopleura and Mesotomura, as well as the strong reduction bears minute scales in radial rows. of the calcareous structures in Tonicina and Tonicia. 1542 be assumed to is It that the cuticula with the minute calcareous bodies was originally a purely dorsal structure, and that the marginal fold, therefore, represented the lateral animal. It margin of the probably rather might have been interrupted anteriorly also posteriorly. With a strengthening of the at the flat head and perhaps and a ventral musculature concentration of the digestive organs, the dorsum bulged higher and the margins sloped downward. The musculature in the lateral was latter strengthened and an edge was developed, which then formed a secondary margin; anteriorly and posteriorly the margins united to form a closed Due ring. to the differentiation upper side, the edge, and the side. The most at the development of the edge, the impetus was given for of calcareous bodies on the lower primitive snails possess an epipodium, i.e. a fold beginning sides of the head and continuing posteriorly at the sides of the body between the mantle and foot; in Haliotis, developed, at the margin bears numerous tentacles and irregularly it where it is formed processes, mainly on the lower side small sensory its attachment runs a strong blood vessel. It most strongly hills and under could be that such a shell shape as in Pleurotomaria and trochids was less suitable for the retention of an epipodium than the ear-shaped shell reason the epipodium in the former fissurellids the folds along with sensory The is of Haliotis, and that for not so well developed; this in have become reduced, whereas a row of tentacles hills has been retained. position of the epipodial folds in Haliotis corresponds to that of the perinotum, both border the sides of the head and of the body. be considered that It must the loricates lack mantle folds and, if expansions corresponding to them are to be visualized along the shell margin, these, in terms of their position in relation to the perinotum, would completely correspond to the condition in Haliotis. In the same way as the marginal fold of the perinotum, the epipodium corresponds to the lateral margin of the ancestral forms; however, the former lacks tentacles, so that it must be assumed that these first developed in the conchiferans, and the fold not interrrupted is at the head as in the epipodium; this condition can be explained by the fact that with the development of the lateral edge, the two lateral folds have only secondarily united anteriorly and posteriorly. It cannot be stated with certainty as to what extent an epipodium has in the higher snails. Some Cocculina species possess a pair of tentacle-like processes on the posterior part of the foot. The opercular lobes of Lacuna on their posterior part have a process on either side, been retained 1033 whereas side are in Litiopa, in addition to 3 cirri. The lateral one pair of similar processes, on either folds of Janthina, which resemble an 1543 epipodium, are in Recluzia not clearly delimited, they do not have a blood vessel the base, and are lacking in the scalids, hence they should at not be considered as a true epipodium. Whereas the bivalves and scaphopods lack an epipodium, one can that the arms of the nautilids along with their sheaths, have arisen from such; the external system is dorsally interrupted by the cephalic assume hood and lateral by the funnel depression, so ventrally posterior part has been lost as a result of and the that it consists of 2 of the epipodiium, whereas parts, similar to the anterior part its its envelopment by the mantle shell. The mollusean foot is originally the ventral, sole-like flattened part of the body provided with a strong musculature, situated behind the head, and serving for attachment substratum and for creeping, the to attached to the shell by bundles of muscles. Its several modifications in the mollusean series. Corresponding to the form, in the loricates it is more or the primitive but in snails, docoglossans, which fissurellids, form of a powerful sucker. become reduced, laterally It compressed head. some In propodium, very little, it may assume which have assumed a special has undergone greater modification in the fin. the is swimming only indicated as a small sucker on the Remarkable also is the foot of naticids, which and has a propodium, the posterior margin of which covers distensible the move has a similar form It such as the haliotids, In the sessile vermetids the creeping sole has heteropods, where the sole is forms, littoral as also in the strombids type of locomotion. body less elongated, occasionally greatly narrowed, and without special glandular structures. in is it form has undergone olivids lateral its the foot is broad, with a crescent-shaped lobes adjoin the shell, but can also be sometimes lateral lobes, which serve wing-like swimming developed in some opisthobranchs (Atyidae, Acera, Gastropteron) and most characteristically in the pteropods; on the other hand the foot of nudibranchs is as a rule rather long and narrow, without used for swimming. Similar organs, are strong musculature and without retractor muscles, in rudimentary or completely lost. The serves exclusively for burrowing. although its form is variable, groups, in which the shell rudimentary. As in become broadened some to is It phyllirrhoids foot of scaphopods is functions similarly in many snails, the foot is bivalves, often hatchet- or finger-shaped, in cemented it protrusible and to the substratum, some the foot is of the primitive cephalopods has form a pair of large lobes, which another to form a tube, in Nautilus they are still enroll against one separated from one another, in others they are fused together to form the funnel. The foot is margin a groove often is provided with special glands. At the anterior developed, which in most cases gives off posteriorly 1544 is surrounded by mucus gland The glandular cells which open into the sole, in higher prosobranchs, have drawn together around a sometimes rather small, sometimes larger a more or less deep median blind sack and cells. cavity, 1034 which is frequently (always ?) used for the production of egg capsules; in janthinids this sole gland also produces the farm-float, which is attached to the longitudinal folds of the posterior part of the sole. Similar glands are also present in structure the known as many bivalves; the sole gland secretes byssus in most cases hornlike, in Anomia by which the animal attaches itself to stones, etc. In animals on sand or muddy substratum, the byssus gland becomes calcified, living rudimentary. On the funnel of the cephalopods, corresponding glands are recognizable as bulges of variable form. The condition of the respiratory organs of great importance for is the systematics of the mollusks. In the loricates, at the sides of the foot, in the groove formed by the perinotum, on either side are a few bipectinate gills, which are attached at the bottom of the groove bases. Their number varies greatly, either side, the acanthopleurids of the gills to the posterior in the holobranchial type The some between 70 and 80 half is by their lepidopleurids have 6 or 7 on gills. The restriction called the merobranclial type, while they extend to the anterior margin of the foot. largest gills are situated near the kidney opening: when with these the series ends posteriorly, they are called abanal, on the other hand, when a few small ones are also present between these and the anus, they are called adanal. Accordinlgy, the merobranchial adanal type (lepidopleurids) considered as the most primitive, the merobranchial abanal type in lepidochitonines, be found Amicula, Cryptoconchus, Acanthochiton, and in Cryptoplax, whereas the remaining groups, including ones, to is is such as Nuttalochiton and Callochiton, some fairly primitive have assumed the holobranchial type; hence, this character cannot be indicative of closer relationship, especially because some species, like Callochiton (Icoplax) puniceus (Gould) and Ischnochiton keili Plate are still called merobranchial. Schizochiton, with merobranchial but has a specially modified form in some gills, is highly advanced, respects. The primitive form of the conchiferans had a pair of bipectinate which were located below the posterior mantle lobes at the base of gills, which they were attached show some similarity laterally to the nephridia. Although these gills with those of the loricates, they cannot be considered as homologous structures, because they differ in their position, number and the innervation. They are called ctenidia. It is from these that development of the respiratory organs has taken place bivalves, and cephalopods, whereas they are lacking in all in snails, scaphopods. 1545 snails, In the gills dorsum with displaced anteriorly, so that they are their apices directed forward. groups with a spiral shell and the two gills are Among possess an asymmetrically placed largely attached efferent vessel, they are free over the lie the zeugobranchs, the gill chamber margin containing the on the opposite margin which is somewhat to the surpassed by the gill leaflets. In fissurellids, the gills have assumed a symmetrical position and, to a variable extent, they are attached to the mantle, partly also on the side of the afferent vessel. The trochaceans have lost the right gill; the left gill is largely attached to the mantle by both margins, and the lamellae of the upper side are gradually reduced the in posterior part, finally fuses with wavy 1035 it, whereas the rachis approaches the mantle and so that the lamellae of the lower side, which folds, arise directly show from the mantle. This process has proceeded farther in the higher prosobranchs, so that all their gill lamellae hang on underside of the mantle. The adeorbids and valvatids, however, possess a bipectinate and protrusible gill, of which it is doubtful whether it should be considered as a new structure. the In the stirps of the docoglossans, which follow the zeugobranchs, both ctenidia are reduced and can be represented by a pair of wart-like elevations, whereas in patellids, instead of ctenidia, on the underside of of lamellae has developed, which is sometimes anteriorly interrupted. Such a circlet of gills is also present in Lottia, but mantle a the circlet in addition there is a bipectinate gill, attached only at the base, which could have developed from a lamella arising from the mantle anterior to the heart. The small lepetids lack gills. The condition in the cocculinaceans similar to that of the docoglossans; the cocculinids possess a pleated lamella attached in the neck, similar to Bathysciadium pacifwum Dall, is whereas the very small are without B. costulatum (Locard), as well as Cocculinella, Lepetella, anteriorly on the right side, a few gill lamellae have developed on the underside of the mantle, and in Addisonia gill. In such have developed on the entire right side with considerable increase in number and size (cf. Fig. 73). Among the neritaceans, the neritids, neritopsids, phenacolepadids, and titiscaniids have a bipectinate nuchal gill attached, similar to that in acmaeids, only at the base; on the other hand, the terrestrial hydrocenids and helicinids lack gills. Also gill-less are the terrestrial cyclophorids, pomatiasids, acmids, assimineids, and the genus Geomelania, but also the marine, in most cases very small, pyramidellids. Very special are the respiratory organs of the ampullariids, in which a septum divides the mantle cavity into a right half containing the gill, and a Among of a left half which serves as the lung. the opisthobranchs, the actaeonids possess a single lamella, with its apex directed anteriorly, gill consisting which can be 1546 considered either as a completely new development in contrast to the ctenidium of most of the prosobranchs or as a homologue of only a single lamella. In other cephalaspideans this gill develops further, wherein it more shifts to the right similar to a ctenidium, in pleurobranchids The pterpods it in and toward the posterior, and at the most cases do not possess Also the structures. leaflets some some is and, when they are seem be to is undoubtedly a special of the shell-less sacoglossans possess leaf- or club- shaped dorsal appendages, condition gills pterotans, they of oxynoids, consisting of several narrow gill on the underside of the mantle, structure; flattens, so that hardly appears like a cavity. present, as in Cavolinia, Peracle, and new can become it same time the mantle cavity in part gills are lacking completely. A similar present in the nudibranchs, several of which (Doridoxa, Heterodoris, Doridoides, the hedylids, phyllirrhoids, goniaeolidids, pseudovermids, and rhodopids) are without gills, whereas others show variously formed processes which attach to the sides of the the anal region. In the scyllaeids, small gill tufts are Similar to the condition in patellids, the lobe-like processes. phyllidiids and dorsum or made of numerous arminines are in developed on the of gills lamellae leaflets on the underside of the mantle. The pulmonates 1036 are originally and predominantly gill-less. In the littoral siphonariids alone, in the spacious mantle cavity, several triangular on the mantle, which are lacking in the related ancylids a gill has developed in a different and gadiniids. In planorbids mantle lobe situated outside the lung ventral of a way, by expansion tuft-shaped gills on the upper side of are there oncidiids cavity. In some gill leaflets are developed the mantle. The gill-less mantle cavity of the above-mentioned groups serves as the lung, with the development of a vessels in the mantle. A more or less strong . athoracophorids, in which the mantle cavity is which lie in a wide blood sinus. In the ancylids more or less reduced, soleoliferans completely lost. tubes, is network of blood shown only in the sends out numerous branched very special condition Whereas, in accordance to what has been the lung cavity said, in various groups of and are sometimes replaced by new structures, they are retained throughout the bivalves, in which they have become rudimentary only in a few poromyaceans. The most primitive snails the ctenidia form of gill gills is have been lost displayed by the nuculaceans: on either side there is a consisting of an axis and two rows of short lamellae; these are in most cases directed downward, in solenomyids they are directed laterally. In contrast to these groups, which are known as Protobranchia, in the Filibranchia the two rows of lamellae are produced intq long threads, 1547 which hang down from the rachis on the sides of the foot and which are as a rule, sharply bent with their terminal parts so that each thread forms an inner and outer limb, and together form 2 leaflets on either side. Originally the consecutive threads are joined with one another only by brush-like, and each contains a septum so and-fro throughout its that the blood flows in to- it length (arcaceans). full Similar are the mytilids, also the trigoniids, in which the threads are As a fused with one another only at the margin. at the blood vessel free ends, an efferent result of such a fusion formed. The is in other gills anisomyarians also consist of threads, which can be identical (Vulsellidae, Plicatulinae, folds, Amussiinae, Anomiidae) or their longitudinal rows form the inner marginal of which are distinctly enlarged filaments (Pteriidae, Pinnidae, Pectininae, Spondylinae, Limidae, Ostreidae). Rarely the threads lack the ascending limb. In the series of eulamellibranchiates, the successive threads are fused to form leaflets, which are pierced by and there are also connections between the two limbs of the threads. The leaflets thus formed may fuse with their free upper margins clefts, on the inner side with the visceral sack and on the outer side with the mantle, as a result of which the mantle cavity an upper chamber. The outer lamella gill is is divided into a lower and sometimes more weakly developed than the inner or can even disappear completely. In the most cases verticordiids the gills are narrow, net-shaped, enclosed in a in incomplete septum, in poromyids they only form 2 or 3 small sieves or rows of holes and in cuspidariids on either side there are 4 or 5 separate holes in the septum, so that true gills are here absent. In bivalves, accessory gills are rarely ctenidia, such as small folds in 1037 some mytilids and in Panopaea, in septum stretched out between the lucinids as folds The is its developed in addition to the above the upper margin of the outer lamella some folds of the cardiids as gills posterior to the foot, and in few on the inner side of the mantle. ctenidia are always present in the cephalopods. duplication in Nautilus; this is Very remarkable probably explainable by the fact that the anterior ones were originally processes of the posterior ones, which subsequently become more independent, wherein the rachis became detached from the body and formed a free process; accordingly, the two pairs of gills are attached to the body with only kidneys, and throughout their length afferent vessels posterior and are situated anterior ones, on the and in their bases lateral to the lie freely in sides, the mantle cavity. facing each The other on the the basal part form thick bands, whereas the efferent vessels run on the opposite are irregularly triangular with parallel folds and sides. The gill two rows of leaflets tubercles. 1548 All possess only one pair of other cephalopods gills, lying symmetrically in the mantle cavity, their bases are attached to the body, and the outer sides are joined to the their apices are directed forward mantle by a band. The form and number of the the side ventral runs efferent blood the leaflets is variable. above which vessel, is On the afferent. Between them, the gill as a rule is traversed by a canal formed by an incomplete fusion of the leaflets with the rachis. Lying in the suspensory band is the "gill spleen," consisting of cells with large nuclei. The anteriormost part of the trunk, which contains the oral opening, often bears the eyes and tentacles. However, originally the tentacles were not yet developed, whereas eyes. The this is uncertain with respect to the have only a narrow sensory fold loricates at the anterior margin of the head; the adult animals lack eyes, but they have been found in juvenile animals. In Haliotis a transverse fold is visible between 2 short eye-bearing processes and, beside the eye-bearers and on the anterior tips of the of which epipodium is a pair of longer tentacles, the structure completely identical with those is epipodium and hence morphologically belong be assumed that this head-fold is margin of the the at epipodium. to the homologous with of the that It can loricates, perhaps the eyes also correspond with those of the loricate larvae, whereas the tentacles on the head and on the epipodial margin are new structures. In the trochaceans the head-fold varies, or fringed, sometimes divided into 2 longer, in sometimes lobed is it most cases branched processes, sometimes reduced {Angaria, Skeneinae); is it the fissurellids, docoglossans, neritaceans, as well as in The processes which bear also lacking in all higher snails. the eyes are also often completely lost and the eyes are situated lateral to the tentacles in the head or they are displaced more or lie less far completely forward on the outer side of the tentacles, rarely they at their anterior ends {Terebellum, Terebridae), when they are frequently contained in swellings or the common bases of the eye- and tentacles can be greatly elongated and separated only terminally (most strombids). The tentacles in prosobranchs are as a rule bearers more or in less long, cylindrical processes; they are absent in the hydrocenids, Homalogyra, whereas Olivella, and Diplomeriza; they are in rissoellids a pair the tentacles. They of similar processes is cleft in Janlhina, developed between are specially modified in the pyramidellids, sometimes more elongated, they possess a groove on the any case contains a special sense organ. The head short and broad, sometimes 1038 outer side, which in of the Cephalaspidea has acquired a shield-shaped expansion, under the anterior and lateral margins of mouth opening sometimes which serves as a tactile which lie the sense organs, and near the somewhat fold-shaped elevated area, organ, and more laterally there is an olfactory there is a 1549 organ which in most cases shows fine transverse folds which occasionally have a bipectinate arrangement (Haminea). Occasionally the head-shield has or 2 pairs of lateral processes. In Paraplysia the form 1 Haminea, so that in that the anterior tentacles similar to is correspond to the anterior corners and the posterior ones to the lobes of the cephalic shield; in Aplysia the form is further modified. Most frequently the opisthobranchs have an anterior pair of tentacles and a posterior pair of rhinophores, which often show a lamellate pair of processes pair although sometimes only one whose homology with one or the other developed, is structure, occasionally doubtful. is Among the pulmonates, the tentacles, only in basommatophorans by the position of the eyes distinctly characterized are in the in most cases head beside the Otina does the head bear a pair of short processes containing the eyes; on the other hand, in the stylommatophorans the eyes are borne in the tips of the invaginable tentacles. Small anterior tentacles are in most cases present although they can be in land snails, occasionally developed independently of the others, as in the Soleolifera; they are absent in the oncidiids, athoracophorids, and Strikingly large oval Some snail of adaptation In the in groups have rudimentary eyes, to life in the most primitive patetlids some vertiginids. lobes are rarely developed (some oleacinids). snails, deep in most cases as a sea, in caves, or result burrowing life-mode. they are in the form of open vesicles, which and acmaeids because of being covered by the remained as shallow pigment cups, in shell have Pectinodonta and lepetids they are hardly indicated any more. Most of the cocculinaceans are blind, in only one species (Cocculina fragilis Thiele) have eyes been found. The pelagic janthinids have rudimentary eyes. In the pyramidellids they are situated in the head are the cause of a in Olivella, and between the ear-shaped processes. Burrrowing habits more or in the less extensive reduction cephalaspideans. of eyes in the naticids, Pteropods have no or very rudimentary eyes. The cave-dwelling Zospeum species are blind. On the small head of the scaphopods the leaf-shaped processes at the mouth opening seem along with the cirri, to represent a situated at the head-fold of Haliotis, but contributed to In it; it new structure, whereas the folds, its base are probably homologous with is possible that the tentacles have also the scaphopods lack eyes. the bivalves the head is reduced, but this is only true for the process containing the mouth opening, because the upper produced into more or less large oral lip, which is lobes, has to be considered as a homologue of the head-fold of primitive snails, which has here acquired a new structure in the lower lip. The small cup-shaped eyes at the ends of the oval lobes, retained in some primitive bivalves, could be homologous 1550 with the eyes of snails; such eyes have not been observed in the nuculaceans, which on the other hand possess more or less long appendages arising at the ends of the oral lobes, each with a strong ganglionic nerve, 1039 they are probably homologous with the head-tentacles of snails. The head of Nautilus has become greatly modified through the hood and the cephalic its individual parts is with their sheaths, so that the homology of cirri uncertain; there is hardly any doubt that the open eyes correspond to those of the primitive snails but whether in this The dibranchiate cephalopods tentacles are ascertainable. to have certainly seem them. lost The seems doubtful it case homologues of the head-fold and the cephalic anterior part of the head along with originally a snout, short which is still the found in mouth opening many is herbivorous mesogastropods, as well as in the opisthobranchs and pulomonates. But some already in families of mesogastropods the become snout has elongated proboscis-like; the channel-shaped prolongation of the lower lip of Capulus proboscis at special, but is to is first be considered as a propodium. The can be simply shortened and elongated, invaginated by means of muscles attached (acrembolic proboscis), as is at the later it can be mouth opening some higher mesogastropods. In (doliaceans and become very long and is enclosed the case in the most highly developed predatory prosobranchs stenoglossans), the proboscis has often in a special sheath, the retractor muscles are attached only at median part of the proboscis, so that the temrinal part along with the mouth opening in the retracted condition always remains anteriorly directed (pleurembolic The proboscis sheath proboscis). which as is separated from the thin proboscis. in it is a permanently invaginated part, a rule attached to the body wall, only in terebrids Among it is the opisthobranchs the pterotans most cases have a protrusible proboscis of varying shape, in cliopsids very long, in pneumodermatids it is provided with suckers, it is is otherwise short and often has cone-shaped processes. The originally short oral tube, actually formed only by the lips, leads which mainly contains a tongue, covered with a conchin membrane, implanted into which are hook-shaped teeth of characteristic form; its posterior end extends into a sheath, at the end of into the buccal cavity, which the continuous formation of teeth takes place; as a moves forward result the wear out membrane gradually anteriorly. With the exception of bivalves and some groups of snails and is present in all mollusks, and is a character to the extent that the teeth cephalopods, such a radula of great importance loricates, teeth, in in systematics. Its structure is very peculiar in the which cutting edges are present mainly on the 5 median whereas the lateral parts bear scale-like plates, except the 3rd row, 1551 attached to which as a rule there a shaft with a more or less broad is Each transverse row accordingly always has 17 cutting edge. on the whole the differences are not very great, important for the systematics of the class. In median plates are taken into consideration, hooked following, plate detachable cutting edge. lepidopleurids is The Lepidopleurus species sometimes broadest has a very hard, black, of the rasping plates of The central plate of structure characteristically variable. longer than broad, but is sometimes posteriorly, ,5 are moderately large, but it strong and is most cases only the of which the central plate and the intermediate plate lying on either side of the and plates, but are nevertheless is variously shaped, the anterior part, nearly in always with a distinct curved cutting edge; the intermediate plate in some species bears 1040 a cutting distinct edge, hooked plate, the cutting edge of which is other species in rudimentary or completely reduced; most striking is it the variability of the is sometimes narrow and unicuspid, sometimes provided with a small, sometimes rather large 2nd point, or also with 3 points. have to be considered to Among these forms, the most primitive ones be those with cutting edges on the central and intermediate plates and with a tricuspid hooked such as in plate, Lepidoleurus algesirensis (Capellini). In Hanleya the central plate broad, with rather a cutting distinct without such, and the hooked plate radula Hemiarthrum in shows Lepidochitoninae; the central plate edge, is a is the tricupsid. intermediate plate The condition of with relationship clear is is the the posteriorly pointed, anteriorly rather broad, with distinct cutting edge, the intermediate plate without such, the hooked plate with 3 cusps, denticulate. The and the cutting edge of the greatest similarity with this Tonicella, although the species are T. somewhat is lateral plate is shown by the radula of variable, but the radula of rubra (Linne) differs only by the slightly different form of the hooked plate. The groups of the genus Lepidochiton, as well as Schizoplax, Mopaliella, and Middendorffia, have cutting edges on the central and intermediate plates and tricuspid hooked plates, the margin of the cutting edge of the lateral plates Nuttallina, Nuttalochiton central plate is sometimes slightly nicked; the radula of and Notochiton also shows similar rather broad, structure: with distinct cutting edge, cutting edge of intermediate plate rudimentary or absent, hooked plate tricuspid, cutting edge of the lateral plate nicked. Of the species of the genus Callochiton, those belonging to the subgenus Icoplax have a well-developed lateral plate with a smooth-margined cutting edge, as well as the genus in Callochiton s. s. and Trachyradsia the lateral Eudoxochiton, whereas plates have lost their cutting edges. 1552 The same type of radula with in the families hooked plates are very strong, whereas Among cutting edges. we find initially is at first inconspicuous, but and several considerable size in Pallochiton, Dinoplax, a many Ischnochitoninae. In Ischnochiton groups and in Lorica and the appendage chitonids, a small not very on the inner side of the hooked plates a wing-shaped appendage develops, which lateral other plates have lost their all ischnochitonids the different rasping plates, but attains been retained slight modifications has of mopaliids and cryptoplacids; in Cryptochiton the tricuspid is also developed margin of the intermediate and intermediate plates are often on the anterior part of the The form and plate. size of the central characteristic in the different groups; as a rule the cutting edge of the hooked plate in the ischnochitonids has 3 more seldom only a or 2 cusps, cusp remains, or the cusps single, pointed are obliterated, so that a broad rounded cutting edge that also characteristic formed, such as is of most of the chitonids. Only in the subgenus Lucilina (besides Onithella) and the genus Schizochiton the cutting edges have acquired 4 more or If less distinct cusps. one compares the rasping plates of the condition, such as one must then becomes clear that the assume loricates with a primitive for the ancentral conchiferans, former are highly specialized, which it is evident mainly in the very characteristic structure of the hooked plates and of the cutting edges of the marginal in the reduction Among plates. the conchiferans, the most primitive snails possess rasping plates with numerous which are more or denticles, developed more distinctly less The radula of strongly on the median field than on the lateral fields. Pleurotomaria characterized is more numerous than 104! in the by the plates on the median field being remaining rhipidoglossans, the central plate and the inner intermediate plates have no cutting edges, whereas the outer intermediate plates are strong and curved hooked-shaped, most lateral plates on their backside near the which are lacking special haliotids acquisition seems long, beside it all end bear a tuft and other rhipidoglossans of small may bristles, represent a of the recent pleurotomarians. The radula of the be quite to on in different, the central plate is broader than either side there are 5 intermediate plates, of which the 2 inner ones are medium-sized, the 3 following ones are very strong and armed with triangular cutting edges; the lateral plates are narrow numerous. The radula of the scissurellids it smallest and the 5th edges. fissurellids, is the largest, all plates is is the bear finely denticulate Similar characters are shown by the radula of the because here again the 4th intermediate plate and the 5th and also clearly different, besides has 5 intermediate plates, the 4th of which the central plate, cutting is the most strongly developed; is the central the weakest, plate of the 1553 Emarginulinae is variably broad, inner intermediate plates denticulate edges, cutting the denticulate; distinctly it it is broadest in Fissurellidea, and like the has only slightly recurved, not or finely only large in Clypidina the cutting edges are outermost intermediate plate most in cases has only one outer lateral cusp on the pointed cutting edge; in Hemitonia there are in addition 2 small outer denticles and in Clypidina a small inner tooth. The radula of the Fissurellinae differs neck of the central plate by the narrow and the broad quadricuspid outermost intermediate The first lateral plate has frequently lost its cutting edge. The radula of the patellaceans is very peculiar, because the bases of the median plates bear detachable, very hard and brownish-yellow plate. cutting edges, and because the radula The most somewhat original form has farther posteriad is narrow and sometimes very long. 5 plates in a row with simple cutting edges, on either side one plate with a broad, split quadricuspid cutting edge, the margin on either side bears three simple The central becomes narrow and loses its plates with small, nondetachable cutting edges (cf. Fig. 23). plate has a tendency towards reduction, edge, cutting so that in it most of the inconspicuous longitudinal ridge; patellids the in it appears only as an Nacellinae the innermost intermediate plate has disappeared; the lateral plates here are often only weakly developed. The radula of the acmaeids has the greatest similarity with that of the Nacellinae: central plate rudimentary, in most cases completely lost, on either side only one anterior intermediate plate with simple cutting edge and one posterior plate with bipartite cutting edge; of the Patelloida there are 2 on either side, in Lottia and lateral plates, in Collisella a small one is retained, they are absent in others. In Pectinodonta the outer cutting edge of the posterior intermediate plate is is cuspidate and fused with the other two to form a more or less long oblique cutting edge (cf. median Fig. 27). The reduction of plates proceeds part of the radula of lepetids, edges have become fused to form a truncated straight or is in still farther in the which the two inner cutting common pointed, whereas the alongside and in most cases remain cutting edge which is two outer ones are situated separate, in Cryptobranchia concentrica Middendorff they have united with the inner ones to form a single long cutting edge; lateral plates similar to Patelloida, with smooth or denticulate cutting edges, are always present. In the series 1042 of trochaceans, the median part of the radula is in most cases represented by a central plate and on either side 5 intermediate however the number of intermediate plates in become reduced to one (Basilissa, Seguenzia, plates, the Margaritinae has Guttula), as in more seldom they are more numerous (Cittarium, some Calliostom species). The central plate in most cases has a constricted cyclostrematids, 1554 neck with more or rarely it less broad lamellae and a pointed cutting edge, lateral assumes other forms (Umboniinae) and may cutting edge its become rudimentary (several turbindis); in Phasianella the central plate has become a narrow ridge or is completely reduced, and in Eulithidium a secondary central plate has developed by fusion of the two inner intermediate plates. In their form the intermediate plates in most cases resemble the central and plate, in the plates are in lateral most cases, narrow, although in the turbinids the innermost become often more or The radula of Angaria less strong. is characterized by the large size of the 2 outer intemediate plates, which are similar to those of Haliotis. Among the neritaceans, the median part of the radula has undergone distinctly differentiated development, but as a rule are 4 central plate edge, in helicinids is two following small, similar to the weakly developed intermediate plate The plates. first intermediate sometimes greatly broadened, with smooth cutting is it either side there lateral weak, without distinct cutting edge, the is plate in the neritids are also on followed by numerous intermediate plates, plates, which on the other hand the outer in the neritids, very strong, with large smooth or denticulate cutting is edge and an outer process of the basal and neritopsids the plates in the median part. In part hydrocenids, titiscaniids, of the radula have become reduced, so that only a few outer intermediate plates are retained. In the stirps of cocculinaceans, the cocculinids rhipodoglossate area 1 still have a typical with numerous narrow lateral plates, whereas the outermost of the 4 or 5 intermediate plates is large and strong, on the other hand in the Lepetellidae the lateral plates are reduced and the remaining plates strikingly differ not only among the known genera but from the Cocculinidae. also Because in the trochaceans the either side is already reduced to one, number of intermediate plates on and the number of lateral plates is decreasing, the taeniglossate type differs but slightly from this condition, because in plate this case as a rule and 2 lateral The rasping on either side there is one intermediate plates. plates of cyclophorids can be derived has been retained in some subfamilies (cf. Fig. from a form which 84): central plate anteriorly rather broad, with pentacuspid cutting edge, intermediate inner lateral plate with 4, the outer one with 3 cusps. modified is the form of the plates and the number of occasionally decreases; the genus Alycaeus ' "Gebiet" -Editors. = is More teeth, characterized area, in the original text is probably in error for by "GebiP" = and or less which large dentition. 1555 lobe-shaped cutting edges with indistinct modification cusps and the greatest and have large simple cutting edges, whereas the rather narrow are lateral seen in the dentition of Cochlostoma, in which the plates is outermost plate has become rudimentary. The other families of architaenioglossans, which have highly variable dentition, the viviparids have most cases rather and thin plates with finely denticulate cutting edges, but the large 1043 live in freshwater, in Campelominae have smaller plates ampullariids the central plate is intermediate plate with cutting edge, lateral with simple cutting edges; short the inner and outer adjacent cusps, plates with strong, pointed cutting edges, in most cases with a small inner adjacent cusp; the radula of lavigeriids (Fig. 90) outermost plate similar to that different, in and broad, with pointed, cuspidate in is also very the melaniids with several cusps. Among the marine taenioglossans, the radula of the lacunids considerable similarity with that of some cyclophorids, shows so that one can think of a certain relationship; the base of the intermediate plate of the Littorinacea always has an outer identation, in littorinids the radula often reaches considerable length, whereas the form of the plates it is lives not only in the sea but also in freshwater, modified, and partly even having invaded the seashore and land, the central plate on on is peculiar in Tectarius species. In the large stirps Rissoacea, which either side often The absent. typical 1 form of dentition, such as families of hydrobiids and rissoids, plate, in its posterior part has or a few small denticles, but which can also be which the cutting edge in that occurring in the shows a posteriorly broadened central most cases has a few adjacent cusps, an intermediate plate with a more or less long lateral process, plates as a rule with finely denticulate cutting edges. and lateral The micromelaniids always lack the posterior denticles of the central plate. A certain similarity is also evident in the radula of the valvatids, but they also lack the posterior denticles and the intermediate plate in Valvata plates s. s. all have a slender dentition in a tip, few genera hand are those is only slightly broadened, plates are finely denticulate, in Borysthenia the lateral without denticles. is Among the Barleeinae, the similar to that in the Rissoinae, on the other in Eatoniopsis, Boogina, and Eatonina characteristically modified. The structure of the rasping plates of adeorbids, as far as known, also approaches that of rissoids. The same is also true of the Assimineinae, in which the central plates in part have retained the posterior denticles and in part have lost them; the form of the plates and their cutting edges varies rather strongly, as a rule they are cuspidate, the outermost plates being more or less finely denticulate, in the more original groups they are moderately broad, in the more highly developed 1556 groups they become very broad and the denticles very fine and numerous, secondary larger denticles are formed due to several deeper incisions (Omphalotropidinae). This radula is very similar to that in the pomatiasids, mainly through the very broad outer lateral plate (Fig. 102). The denticulation of which two subfamilies. differs In the planaxids and Batillariinae, we find on the central plate a pair of posterior teeth, which however seem to be scarcely homologous with in the those of the Rissocea, also noticeable lamella on the outer lateral plates, is pomatiasids; a corresponding lamella Among the presence of a broad thin which is may the cerithiaceans, the Litiopinae some group, the dentition of which shows similar to is represent the most primitive shows considerable more or differences, the intermediate plate is often produced into a long process. Such a condition in which the plates bear is also shown by denticles, fine 1044 find pointed, a few lateral more or denticles, in related less strong lateral plates, as also in less the radula of Amaltheacea, but the lateral plates have a tendency to become elongate and pointed, and we of the similarity with that the form of the plates within the stirps lacunids; the in that developed in Cerithidea. also groups as a rule sometimes with only whereas the other the Triviinae, subfamilies of cypraeids have retained the characteristically formed lateral of which those of the Amphiperasinae remind of the plates, pomatiasids on account of the strongly broadened outermost plate. Some larger or smaller groups of the taenioglossate radula, either plates, have deviated from the normal form of the in the very peculiar structure or in their different number. Microdiscula, the rissoellids, the mathildids, and the solariids of the genera Torinia and Philippia, have only 5 plates in each row, in the homalogyrids, in Turritellopsis and Lamellaria, the lateral plates are completely lacking. in the choristids on either side there are 3 or scale-shaped marginal plate (Fig. side there has 5 may lateral be 3 plates in 164); 4 side. the other hand, and a small species on either Turritella lateral plates, the struthiolariid on either On lateral plates genus Perissodonta The genus Solarium from differs by the loss of the central plates and a considerable increase in the number of the remaining plates. The radula of the triphorids has Philippia undergone still greater modification, with its very small bi- or tricuspid plates in several rows, in the trochaclidids with numerous numerous in Aclis uni- to tricuspid teeth which are sometimes thin, pointed more or less fairly strong, and lamellae, in the ptenoglossans (Figs. 222 and 224) with and Liostraca with numerous, very small, needle-shaped From the taenioglossan radula the stenoglossan radula loss of the intermediate plate and one lateral plate, is teeth. derived by so that the typical 1557 stenoglossan radula has one central plate and a pair of lateral plates in each row. Very probably the central plate primitively has 3 teeth and the lateral plates are families, simply pointed, because on the central plate may increase, secondary denticles, in some this form and the other forms can be derived from The number of in Pseudanchis (Columbellidae), buccinids, in nassids, in Olivella (Olividae), in in marginellids. On teeth some muricids through smaller in way in a different present in various is it. some mitrids, and number and may the other hand, the teeth decrease in disappear completely, mainly in the columbellids (Pyrene and Columbella) and some buccinids (Liomesus, Beringius). The central plate of Halia and Volutomitra (Volutidae) has a single long cusp, and in Cancellaria this plate has assumed the form of very long and narrow lamella. toxoglossans originally the central plate most cases it is In well developed, but in still becomes small or disappears completely. In some families the lateral plates have developed teeth on the posterior margin, as in the columbellids, nearly and in the 2 last all buccinids, galeodids, nassids, fasciolariids, mitrids, mentioned families the the toxoglossans the more or less lateral plates are elongate lateral acquired a wing-like, thin process (Turrinae), 1045 very broad. In plates have often Brachytominae and in the the remaining conids they are modified into groove-shaped teeth often with barbs, their basal membrane is reduced, so that they into the end of the proboscis and are used as terebrid genus Hastula are similar, whereas simply pointed, solid structures. The project singly The teeth of Diplomehza they stylets. in lateral plates are completely the are lost in Cylindromitra, most of the volutids, and in Cancellaria and marginellids. Several groups of prosobranchs have completely lost the radula, such as the partly parasitic melanellids, the stiliferids and Thycinae, the pyramidellids, as also magilids and the genera Scaphella, Admete, and Terebra. A survey of the phyletic development of the dentition in the prosobranch series shows structure, the number of that, apart from the few groups with abnormal plates in the transverse rows has consistently decreased, so that the extreme form shows only one central plate without lateral plates or only one pair of a result of the loss of a lateral homogeneous have attained the most peculiar plates without central plate; as basal membrane, the toxoglossans structure. The opisthobranchs show an independent parallel development of One can assume that, like in the ptenoglossans, first of all a form developed with numerous plates, differing from the normal taenioglossan form. The great variability of dentition among the genera of actaeonids is striking both in the form and size, as well as the number of plates, which may be considered as the primitive condition. They lack the rasping plates. 1558 a central plate, as in the ringiculdis, hydatinids, and notodiaphanids, and in most of the On and gastropterids. philinids, philinoglossids the other hand, the diaphanids have a well-developed central plate, in Toledonia in addition on either side there is a scale-shaped lateral plate, which is lacking in Newnesia. Approaching the latter are the sacoglossans with one longitudinal row of plates, while the bullariids have 2 plates with cuspidate cutting edges and a small scale-shaped plate on either side of the broad, denticuilate central plate, the atyids, aplysiaceans, most of the Pterota, the umbraculids and pleurobranchids have numerous these are related the Doridacea, in which the central plate well-developed, sometimes plates lost, and the Aeolidiacea, which the in have a tendency toward reduction, so that some of have a single-rowed radula, plates. To sometimes is lateral its families retusids of the like the sacoglossans. Some opisthobranchs have no radula: the cephalaspideans; the genera Corolla, Gleba, Laginiopsis of the pteropods, the also, Oleidae, Phyllidiidae, Dendrodoridinae, Tethyidae, and Rhodopidae. In certain groups we come of pulmonates which may possibly be considered as the initial across a form of radula form, in which all plates have an inner and an outer cusp on the pointed cutting edge. Very often become more or the plates closer to the margin have from those of the median differentiated part, less strikingly but on the whole, the modifications of the -radula within this subclass are less extensive than in the other two. Among the ellobiids the lateral plates of Carychium have a small inner and outer cusp on the pointed cutting edge, the broader marginal plates have a few small cusps; in the Pedipedinae the lateral plates lack the outer cusps; the radular plates of the Ellobiinae are their cutting edges tend The radula of of the the Amphibolacea (Fig. 560) lateral plates more modified, toward enlargement and simplification of the chilinids, and denticulate and are arranged latiids in peculiar. is The (Fig. 558). cutting edges and physids are broadened oblique rows, whereas in the lymnaeids and planorbids they have retained the more original form and among arrangement; others it is The most some 1046 place in habits the ancylids some still have a similar dentition, in considerably modified (Figs. 579 and 580). striking modifications terrestrial or with arboreal characterized by more or of the rasping plates have taken pulmonates associated either with predatory life. The radula of less strong, narrow, the predatory snails is claw or thorn-shaped plates arranged in oblique rows; such are found in the rathouisiids, in oleacinids and testacellids, Streptaxacea. The in daudebardiines, trigonochlamydids and in the dentition of tree snails shows enlarged, especially 1559 broadened cutting edges on the plates which are arranged in oblique rows; such a form has developed in genera belonging to several groups [Peruinia (Fig. 626) (Clausiliidae), Rhinocochlis and Sasakina (Fig. 692) Oxychona and Zaplagius (Xestinae), 710) (Bulimulinae), Gaeotis (Fig. 721) (Amphibuliminae), the Urocoptinae (Figs. 727 and 728), Amphidromus (Fig. 739) and Calycia (Fig. 741) (Pleurodontidae)]. A (Fig. peculiar development has taken place in 2 helicid groups (Vidovicia and Allognathus), wherein the large radula numerous rows of beset with is very small, narrow, hook-shaped /denticles. The radula of in the scaphopodsl is very uniform, always with 5 plates each transverse row, of which the central one and the two outermost have no cutting edges great (Fig. 786). The cephalopods also do not Each transverse row of the radula variability. teeth in show Nautilus consists of 13 plates with simple, partly long, partly short, cutting edges The dibranchians possess (Fig. 868). 7 plates, in most cases with simple pointed cutting edges, occasionally also with a pair of toothless marginal plates in each row. In some groups the bases of the 3 median plates form Only the octopods have undergone distinct pointed outer cusps. modifications, the most striking of which plates in distinctly radula has become Cirroteuthacea). patellids, below the anterior end of the radula, there transversely pleated bulge (sublingual which bear a strong cuticula on is the strong broadening of the is rarely the 887); rudimentary (Thaumeledone) or has completely disappeared (Spirulidae, In Bolitaenacea (Fig. the most cases variable, in it around the mouth opening is the organ), their anterior side; in individual acmaeids is folds this a of organ covered by a denticulate cuticula, the area may also show similar denticulations. Such structures also occur in the neritids, and in Cocculina species they are in the form of small bristles. armature of the The jaw is Some of the doridids possess a special lips. a plate situated on the dorsal wall of the buccal cavity, opposite to the anterior part of the radula. In most cases and a cuticula and originally parallel rods epithelium such a jaw it is not yet developed, in bivalves Among the snails also in rudimentary or has been totally lost. It consists of it It protects the it has been many groups is lie free has like the become in the lacking, the anterior marginal outwardly reflected, so that here a sharp edge a large portion does not lost, it shows a peculiar condition docoglossans, in which the layer of rods is bipartite. covers against injury from the radular teeth. In loricates entire buccal mass. part is it is formed, whereas toward the buccal cavity, but is covered by cartilage, muscles, and the sensory palps, which are attached to it. The cymatiids and doliids have a pair of jaws which are completely 1560 separate from one another, those in the latter are produced anteriorly into hooks. Among the Trochinae a few genera have lost the jaw, as also the Neritacea and Cocculinacea, in which cuticula. 1047 It is weakly developed it is developed merely as a simple the littorinaceans and in is not or scarcely present in the pomatiasids, assimineids, trochaclidids, melanellids, stiliferids, heteropods, most of the cypraceids (except pyramidellids, Triviinae) and stenoglossans. Among the opisthobranchs also, the jaw has been lost in several groups: the Diaphanidae, Retusidae, Scaphandridae, Philinidae, Philinoglossidae, Aglajidae, of the pterotans the Clionidae, Thliptodontidae, Anopsiidae and Laginiopsidae, also the sacoglossans, the umbraculids, some polycerids, finally the hedylids, Tethys is and the phyllidiids, and doridids and Rhodope. Among the pulmonates the jaw lacking in the amphibolids, gadiniids, most of the oncidiids and achatinellaceans, and some predatory systrophiids (?), trigonochlamydids snails: rathouisiids, oleacinids, and Streptaxacea. Occasionally the rods of the jaw are peculiar, in the rissoellids they are rhombic and are finely denticulate on one side, in Turritellopsis are basally broadened and distally provided with a they few small cusps, in Microdiscula they are small in number and are arranged arch-shaped, the more or less long knife-shaped with finely The rods of some opisthobranchs also have denticulate margins. The jaw of aeolidiaceans is sometimes strongly developed, the two halves may fuse together and acquire a cutting edge. In the buccal mass of Acera and aplysiids, besides the jaw, there are numerous minute teeth on the dorsal wall, and most of the Pterota have evaginable hook sacks. The jaw of pulmonates is in most cases a half-moon-shaped, more or less strong structure, it is rarely distinctly composed of rods (ellobiids) or platelets (vaginulids, some endodontids), in the succineids and outermost are the largest, denticulate anterior margins. athoracophorids it has acquired a broad reflected lamella (Elasmognatha); frequently the center of the concave margin has a tooth-shaped projection. More or less numerous folds are developed on the ribs in many jaw of bulimulids and jaw has helicaceans. In the lymnaeids and planorbids the a pair of lateral processes. The jaw of scaphopods overlies an epithelial strongly developed; the is horseshoe-shaped, with sharp edge, and The jaw of cephalopods is much more upper jaw, corresponding to the jaw of gastropods, fold. consists of a broad palatal plate and an outer plate which is fairly broad only in the center and rapidly narrows toward the sides, the cutting edge forms a pointed tooth; besides the upper jaw, the cephalopods also possess a lower jaw, the two together serve for biting like a parrot's beak, in Nautilus the internal esophageal lamella is not broader than the 1561 outer plate in contrast to the Dibranchia, in which the outer plate distinctly undergoes little The usual. modification, in the bolitaenaceans the radular sack bears a horny cuticula mollusks the buccal cavity and In is narrower than the esophageal lamella. The form of the jaw jaw is armed with softer than thorns. or the oral tube, are as a rule lips, provided with stomodeal glands, which develop from epithelial mucus cells. The loricates, on the anterior part of the dorsal wall, possess only one pair of mucus glands more or animals, and subradular blind sack the form of sacks, which are simple in the in small less folded in large animals; the posterior part is of covered by glandular epithelium; also salivary glands are absent. Similar mucus esophageal sacks oglossans but also in 1048 still the higher forms. are developed not only in rhipid- lower taenioglossans, they are disappearing in the Opening beside their anterior ends are a pair of salivary glands, which are very rarely absent (Neritacea and Cocculinacea, Trochaclididae, Melanellidae). or they may be more correlated partly They may be simple tube-shaped glands or less highly branched; their structure with the Among phylogenetic relationships. may be of the animal, but also with their size Pleurotomaria, the primitive snails, Haliotis and fissurellids have branched glands, among the trochaceans such glands have been reported in Calliostoma, they probably also occur in on the otherhand, simple tubes are present others, Gibbula and Monodonta. and each in others like glands are profusely branched In patellids the divided into 2 parts, which open close together into the is anterior part of the buccal cavity, each with probably provide different secretions. In its narrow duct; the two parts scalids 2 pairs of tube-shaped glands are present, one pair of which opens into the sheaths of a pair of horny some stylets and probably produce a toxic secretion, and other glandular tubes lie on the outer side of the jaw in addition plates. The glands in Recluzia are similar, but the true salivary glands form distinct lobes, jaw whereas are in Janthina both pairs are tube-shaped, the ducts near the more weakly developed and the stylets are lacking. The glands of the doliaceans are very strongly developed and produce an acidic secretion in most cases sulfuric acid; in Dolium, at the beginning of — each excretory duct, also a lies small acinous accessory gland. The salivary glands of the rhachiglossans as a rule have a similar, structure; besides these, several sometimes paired, sometimes unpaired, as the 2nd elliptical pair of salivary glands, glands with long, compact groups also possess agland which in in Volutocorbis Melo there terminally joined is it is is considered a pair of small excretory ducts; in Cancellaria there are 2 pairs of tube-shaped glands, the longer of which discharge at the mouth opening; Oliva has an unpaired gland with narrow 1562 excretory duct and the Mitrinae have a long tube-shaped protrusible poison gland. It is and whether they not certain whether all all these glands are homologous have the same function. The structure of the salivary glands of the toxoglossans is very different; here they are very unequally developed, the right one in contrast the left one is is medium-sized, simple tube-shaped, modified into a large poison gland with a very long excretory duct and an unbranched gland surrounded by strong musculature, with the secretory cells probably situated in the outer part of the muscular sheath. In the opisthobranch series the oral tube glands are often strongly developed; the salivary glands in most cases represent a pair of simple tubes, in oxynoids they form a pair of bundles of fine tubules. In the notaspideans the two salivary glands are in the form of more or less branched, often interconnencted masses and their excretory ducts in most cases have an ampulla (Pleurobranchidae) or a transverse connecting duct (Umbraculum); in addition, there is an unpaired, often very strongly branched gland opening into the oral tube, acid. The its secretion contains sulfuric salivary glands of nudibranchs are variable, they are sometimes very small, in other cases they are strongly developed, as in Sphaerostoma and especially In in Armina, where they form many small tubes. the pulmonates they are in most cases lobed, more seldom roundish. In scaphopods the They lack oral tube forms a glandular pouch on either side. salivary glands. In the bivalves, along with the buccal mass, The pharynx of Nautilus on either side flat, somewhat lobed gland with very short excretory duct; this gland cannot be considered homologous with the salivary glands of snails. Similar glands are more or less developed also the glands have also disappeared. 1049 of the tongue contains a broad, in the Dibranchia, in Spirula as minute irregular depressions in the mass and on the subradular organ; they are best developed in the octopodids, where they have moved out from the buccal mass and are in the form of paired masses, the excretory ducts of which open into the radular sack. In addition, the dibranchians possess a poison gland lying behind the buccal mass and opening into the subradular organ by a long duct; occasionally it is paired and the excretory duct is bifurcated; this again is a new structure, which is not posterior part of the buccal homologous with similar glands of some snails. The foregut of the primitive mollusks is not a simple esophageal tube, but is provided with 2 glandular sacks, it on both sides. They which are connected with are distinctly developed in the loricates, scaphopods and most of the prosobranchs. In the former the sacks are separated by muscle bundles posteriorly from the esophagus, so that they are connected 1563 only with its anterior part; The epithelium forms villous elevations. its foregut of the prosobranchs has undergone a rotation of about 80°; in 1 the primitive groups the glands are connected throughout their length with the median part which internally it separated only by longitudinal is are variably developed; when they are distinct both dorsally appear to be the glandular sacks lateral, reduced so that only a dorsal groove mainly folds; has villous or fold-shaped elevations. The longitudinal folds is when and the ventral present, ventrally, folds of the esophagus, then the gland in the posterior part are which may happen to is be considered as a ventral structure. The esophageal pouches of the neritids numerous are rather short, internally with folds, in Hydrocena they are long and only slightly lobed, posteriorly in the form of a blind sack. Cyclophorus has esophageal glands, which are anteriorly channel-shaped, posteriorly sack-shaped; open in Pila they represent rounded the beginning of the esophagus through at Ampullarius species the esophagus is short greatly widened. sacks, ducts, which one in The esophageal glands of Viviparus are moderate expansions without sack-shaped part, of the longitudinal folds only the dorsal ones are developed. In the assimineids (Pseudocyclotus) the esophagus anteriorly has a pair of lateral grooves, which then fuse ventrally and posteriorly terminate as blind pouches. The in turritellids and solariids have a long and narrow esophagus, but the groups Amaltheacea, Calyptraeacea, Strombacea and Heteropoda also the esophageal glands are weakly or scarcely developed. In contrast, the Naticacea, Lamellariacea and Cypraeacea have a very well-developed gland with numerous lamellae. The esophageal gland of the Doliacea bulge with many folds, delimited by a pair of Dolium there are also numerous gelatinous pads on the longitudinal folds, and in the blind sack at the posterior end of the represents a ventral longitudinal folds; in gland fine folds with special epithelium are developed. The Rhachiglossa also possess well-developed foregut glands. In muricids these consist of a smaller part situated directly on the esophagus and a larger part opening cases a more or into large less by a duct (Leiblein's gland). it It is in most tube-shaped appendage of the foregut. Because, according to more recent opinion, the poison gland of the 1050 toxoglossans represents one of the two salivary glands, it cannot be homologous with Leiblein's gland and hence the esophagus lacks special glands. In the opisthobranchs also it is in most cases simple, sometimes distinctly widened; some sacoglossans have a more or less large suctorial crop on the buccal mass and a glandular tube may be present on the esophagus. The esophagus of Nautilus is greatly enlarged, in decapods it is thin, in octopods it often has a lateral crop-like dilation. 1564 The more or less enlarged stomach receives the originally probably symmetrical excretory ducts of the large digestive gland, although this symmetry of the stomach is wider is more or less greatly disturbed. In general in herbivores than in carnivores. The stomach of sack-shaped, wherein the cardia and pylorus have The pleurotomariids possess a well-developed structure is also found more or less distinctly come close together. spiral blind sack; in many it snails is often such a trochaceans, but the scissurellids and fissurellids also possess a blind sack, on the other hand it is lacking in the docoglossans and most neritaceans. Sometimes, The stomach shows Whereas folds or constrictions separate different parts. most striking differences primitive groups in the series of opisthobranchs. (Actaeonidae, Ringiculidae, the the Diaphanidae Hydatinidae, and the subgenus Laona of the Philinidae, also the Gastropteridae and Aglajidae) possess a simple sack-shaped stomach, in other groups hard plates are developed in its anterior part, which can be worked against one another by strong musculature. Their form and number is important for systematics. In Bullaria, besides 3 strong, quadrilobate plates, there are few cone-shaped spines, the 3 plates of the atyids are keeled and more or less strongly transversely furrowed; in Haminea, anterior to also a are these, there are also 3 pairs of small denticles; the in the Retusidae and Scaphandridae and Philine s. s. is somewhat in 3 plates Scaphander the plates are calcified, one smaller than the other two. The stomach of Runcinidae contains 4 cuspidate shaped plates form of the different, in plates; several pyramid- 2 to 3 transverse rows are present in Acera those in the Aplysiidae are similar. The thecosomate pteropods also possess a few masticatory plates. numerous small The stomach of the umbraculids is armed with The plates or teeth occurring in some nudibranchs teeth. are not homologous with those of the pleurocoels; Marionia has numerous narrow plates, Scyllaea and Melibe have a ring of plates and Bornella longitudinal rows of thorns in the posterior part of the stomach. In the shell-less sacoglossans, the liver has lost its Hermaea it forms 2 lateral compact form, in canals with processes which branch in the dorsal appendages, in elysiids the branches extend into the lateral folds; in the limapontiids the digestive gland is not greatly branched, but is divided into 2 anterior and 2 posterior main parts. In the aeolidiaceans also, this gland has undergone a similar modification to a variable extent, in Heterodoris it forms 3 main lobes with short terminal branches, in the stomach of Armina on either side opens a small and posteriorly a large branch, similar to a few other groups. In the hedylids and pseudovermids the branches are not very developed; the liver of the phyllirrhoids has 3 or 4 simple branches. The branches form a network in the body wall of the zephyrinids and notaeolidiids; in a few groups the branches extend 1565 appendages and open externally into the dorsal 1051 ends an expansion their cally modified is formed, which The contents cells. is consists been derived from granules of the at their ends, on each of covered with characteristi- of cnidocysts, which have liver cells. The stomach of pulmonates has undergone fewer modifications. In basommatophorans it is in most cases strongly muscular and is provided with a small blind sack. The stomach of the rathouisiids forms the a long blind sack, which, along with the hepatic ducts opening into it, occupies the entire posterior half of the body. A similarity certain dentaliids. As in some with this snails, the which contains a a blind sack, blind sack (Adesmacea). is shown by the stomach of bivalves stomach of the in most cases has crystalline style, rarely also an additional The cephalopods also have a blind sack, opens into the posterior chamber of the stomach, and roundish (Nautilus, inrolled, as in Sepia), sometimes long and more or most of the dibranchs. The which are further divided halves, also the 2 halves are separated, in the loliginids it is is liver less is spirally of Nautilus consists of 2 into lobes, in the spirulids it which sometimes and sepiids otherwise in most cases undivided, traversed by the esophagus. The pancreas constitutes a part of the liver, adjacent to the beginning of the excretory ducts or is developed within them. The one shows 2 loops, which become more complicated in the higher groups, most strongly in the family Chitonidae. A single loop is formed by the initial form in snails, as also still happens in the series of trochaceans. The intestine of loop. intestine in the primitive herbivores always forms at least Among fissurellids is the loricates, somewhat the longer, taenioglossans a few old forms in most cases it is and very long still also has a short intestine, in a nudibranchis it in the patellids. have a moderately long Among the intestine, but short and scarcely coiled, as also in the stenoglossans; the terminal part of the intestine in simplest form is short; is often distinctly thickened. Actaeon few other pleurocoels in Calma lacking. it forms Among 1 or 2 loops, the taxodont Area as a single loop, similar to some nuculaceans, whereas in Nucula the loop has become elongated by inrolling; the intestine of Solenomya is very short, also in poromyaceans; in most it forms few bivalves, loops. Among the cephalopods the intestine is as a rule short, in Nautilus with one loop and in Tremoctopus with several coils. On the rectum of some snails, blind sack-shaped evaginations have developed, which do not have any great phyletic significance, thus there is a narrow tube in the fissurellids, a branched gland in the naticids and muricids; among Much more the pulmonates, strongly developed some is oncidiids have a glandular tube. the ink-sack of the dibranchiate 1566 cephalopods, which however in lacking in the cirrate octopods and in the Bathypolypodinae. The condition of the nervous system is of great importance for the recognition the phyletic interrelationships of mollusks, mainly the different classes and its development in its form the series of snails. in The nervous system of loricates shows a primitive structure, which in most cases reminds of some worm-like animals, especially Solenogastres, mainly through the presence of a pair of gangliar ventral cords and a pair of 1052 lateral rectum. is cords which posteriorly merge into one another above the The head contains a anteriorly part. The and especially gangliar ring around the oral tube, which laterally much stronger than in the posterior anterior half of the ring gives off 3 series of nerves, above those to the perinotum, in the center to the horseshoe-shaped head fold, and below those half of the ring. to the lips, corresponding to those From from the posterior the initial parts of the latter arise connectives to the ganglia of the subradular sense organ and to the buccal ganglia, which innervate the musculature of the buccal mass. These ganglia also form an esophageal ring and originally consist of 2 pairs of small ganglia; the posterior sheath. From commissure lies above the beginning of the radular the lateral parts of the large esophageal ring arise posteriorly both the ventral as well as the originally joined with lateral ganglionated cords, which are one another by several transverse connectives, although the connectives between the ventral and toward reduction, at any rate in some lateral cords tend species only a few or none have been found. While the ventral cords supply the foot, the lateral ones innervate the perinotum, the musculature between the shell valves, the aesthetes and the gills, at which small ganglia may be present in the lepidopleurids. Among the conchiferans, the nervous system of only the most primitive gastropods shows enough similarity with that of loricates that definite homologies are ascertainable; mainly the esophageal rings and the pedal ganglionic cords differ little. Because in Haliotis, which is especially suitable for comparison, the epipodial folds terminate at the cephalic tentacles and, unlike the perinotum of loricates, are not continuous anterior to the head, the nerves corresponding to those going from the anteriormost part of the esophageal ring to the perinotum are lacking; the ganglia of the subradular organ and the anterior commissure of the buccal ganglia are also absent. The nerves corresponding in the two groups are those to the head fold and to the anterior part of epipodium = perinotum, in this connection loricates lack epipodial tentacles it only needs to be considered that the and eyes, whereas in Haliotis the lateral swellings of the esophageal ring give out nerves to the large cephalic 1567 and on either side one nerve tentacles, to the eyes, the anterior part of the ventral In wall. become sparse, connectives, so that this nevertheless the part is latter to the dorsal body gangliar cords the cells have to be designated as cerebropedal on either side give out a pair of body nerves to the epipodium and to the dorsal Beside these wall. connectives, a 2nd pair of connections between the esophageal ring and the ventral cords has developed, running over the cerebropedal connectives and reaching the dorsal part of the ventral cords. This part is joined with of the other side by a strong garlgliar commissure, and it gives off that another nerve to the dorsal wall, a ne;rve into the mantle and a gangliar strand, the so-called visceral commissure, which has assumed the form of an 8 as a result of the peculiar twisting of the visceral sack along with the shell against the foot and head, in which the part arising from the right pedal cord runs left left above the intestine, and that arising cord runs to the right below the intestine. The dorsal from the initial part of the pedal cords and of the visceral commissure, giving off the mantle nerves and the upper connectives to the esophageal ring, pleural ganglia. The pedal cords is known as the are connected with one another farther posteriorly by several commissures arising from the ventral half and send nerves to the foot, to the epipodium, and nerves proceeding dorsally from 1053 the inner side of the dorsal half, which correspond with the anterior nerves to the dorsal wall and probably also to both mantle nerves from The epipodium contains a gangliar nerve net, which The visceral commissure inner margins of the two mantle lobes as well as the the pleural ganglia. serves the sense organs and the musculature. innervates the and viscera, In is connected to a pair of branchial ganglia. comparing the most primitive snails with the loricates, if we accept the homology of the epipodial gangliar with the lateral cords, the main difference then which at all is the gangliar visceral attached ctenidia; also correlated connectives. commissure of the former, events has arisen along with the mantle However, it is lobes and the the development of the cerebropleural also needs to be emphasized that the nerves corresponding to those supplying the dorsal body wall of Haliotis are not known in the loricates, and that the dorsal musculature in the latter is innervated from the lateral cords. The nervous system of Pleurotomaria haliotids mainly by the fact that the visceral differs from commissure that of the arises not from the anterior end of the pedal cords but from the cerebropedal connectives, and is asymmetrical, extending farther forward on the right than on the left; in addition, the fold is epipodium is more weakly developed and a head commissure absent. In the trochids the beginning of the visceral has a similar position as in Haliotis, but in this case, along with the right 1568 gill, the ganglion belonging to has been it lost; at the connective to the branchial ganglion and at the origin of the visceral nerves, the ganglion cells have drawn together to form more or less distinct swellings that are as the supraintestinal and the visceral ganglion, whereas a known subintestinal ganglion is still scarcely delimited; as a rule a connection joining the latter with the right mantle nerve and of the supraintestinal ganglion with the left mantle nerve have developed, as they are present most prosobranchs. The pedal cords of the Fissurellidae are considerably shortened, and do not lie within but on the musculature; epipodium forms a series of tentacles with sensory hills, the ganglia of which are not in interconnected. In the distinct docoglossans the posterior part of the esophageal ring contains ganglia for innervation of the palps lying beside the oral commissures between the pedal cords, besides the anterior main commissure, are in most cases restricted to only one or two in the aperture; the posterior part of the foot; short gangliar bridges connect the anterior ends of the pedal cords with the well-developed pleural ganglia, each of which as a rule sends out 3 strong nerves into the mantle, in which, along the marginal tentacles, a gangliar nerve ring has developed, which therefore cannot be considered as a homologue of the The fairly weak visceral commissure hence the connective of the one is is left pleural lateral cords of the loricates. somewhat displaced to the right ganglion with the subintestinal of the right pleural ganglion with the distinctly longer than that supraintestinal one, whereas, conversely, the nerves to the gill rudiments situated left on the neck are longer on the left than on the right. From the branchial ganglion a nerve runs out on the underside of the mantle obliquely forward and to the right, corresponding to the left pallial of the zeugobranchs; in the acmaeids from this nerve near its nerve beginning, branches off the branchial nerve. 1054 The nervous system of the neritaceans shows several striking characteristics. Due to shortening of its connectives to the pleural ganglia, the subintestinal ganglion has come so close to them that in most cases it lies between them and in immediate contact with them; and together with the anterior ends of the pedal cords in which the statocysts often unlike in the trochids, the lie. gill In addition, it is of the neritids it forms a narrow ring quite remarkable that, is not served by the supraintestinal ganglion, but that the branchial nerve is a branch of the pallial nerve, which arises and helicinids lack the from the gill and left pleural ganglion; the hydrocenids this nerve. The nervous system of the cocculinaceans is more concentrated. A commissure between the cerebral ganglia seems to be absent, the labial small pleural ganglia lie above the larger pedal ganglia which have only 1569 one commissure. The posterior part of the mantle pleural ganglia, on the other is innervated by the hand the supraintestinal ganglion gives off a strong nerve into the anterior part of the mantle, a branch from which enters the gill. Among close to the architaenioglossans, the viviparids and cyclophorids are the both of them have pedal trochids, commissures and a normal commissure nerves; the pallial to retained in the viviparids still cords with a few commissure with weakly developed which are connected ganglia, parietal visceral reduced is the labial in the cyclophorids, whereas the pleural ganglia, which in the ends of the pedal cords are former closer to the cerebral ganglia; the in the connectives of the parietal become more shortened weak labial the anterior lie at nerves have ganglia with the pallial in the cyclophorids, especially ampullariids also possess a lie cyclophorids on the right. The commissure, the pleural ganglia the anterior ends of the pedal cords, the subintestinal ganglion at fused with the right pleural ganglion and is joined with the is pleural left ganglion by a connective situated posterior to the pedal commissure, as is connection between the straight supraintestinal connective is ganglion pleural left conspicuous; is A and the visceral ganglion. also the case with the supraintestinal strong, in formed only by a branch of the ganglion and the place in its Lanistes Hence pallial nerve. a in this case a zygoneury has developed on both sides. Among the marine taenioglossans, the littorinids to the trochids, but after the loss ganglia have become displaced have come very close to of the labial show close relations commissure, the cerebral farther posteriorly and the pleural ganglia them; the pedal ganglia are no longer cord- shaped, but are rounded, anterior and posterior to each ganglion lies a smaller ganglion, of which the posterior ones in Lacuna are joined by a commissure; in commissure both the visceral parietal developed and are connected with branches of the Approaching some this condition, ganglia are well pallial nerves. although with certain differences, are other groups, such as the planaxids, the cerebral ganglia of which have a shorter commissure and are connected with the pleural ganglia, the subintestinal ganglion also closely adjoins the left pleural. hydrobiids also these ganglia and the supraintestinal ganglion together; is system similar to that the and are lacking. 1055 in similar. is in most cases present; the The pomatiasids have a nervous littorinids, the connectives between the parietal ganglia are long, small ganglia Among the close commissure a posterior pedal condition in the valvatids pleural In lie on the pedal ganglia the cerithiaceans, in the Pleurocerinae, Melanatriinae, and Melanopsinae there is a long cerebral commissure and distinct connectives between the different ganglia, but the cerebral and pleural 1570 ganglia in most cases the left lie close together and the subintestinal ganglion on pleural ganglion, while it is often joined with the right pleural ganglion by a straight bridge. Among the ptenoglossans, the scalids have short commissures between the cerebral and pedal ganglia, and attached to the former are the pleural ganglia, with left which the supraintestinal ganglion is connected by a shorter right connective, whereas the subintestinal ganglion is and a longer joined only with the left pleural ganglion. In Janthina, as a result of the very large size of the buccal mass, the esophageal ring is greatly widened, the cerebral and pedal commissures are long, the pleural ganglia are fused with the cerebral ganglia and each parietal ganglion is joined with both pleural ganglia, not quite in a straight line with that of the same side. Both parietal ganglia of the capulids are joined with the pleural ganglia by distinct crossed connectives, and the subintestinal ganglion is joined with the right pleural ganglion by the pallial nerves; the long groove-shaped lower lip is innervated by the pedal ganglia and is homologous with the therefore Vanikoridae, anterior foot lobe of the Amaltheidae, and Trichotropidae. The nervous system is much more concentrated in the calyptraeids, in which the subintestinal ganglion near the right pleural ganglion and zygoneury is broadly joined with it; a lies left not yet developed in Calyptraea, but in Crepidula the is supraintestinal ganglion lies between the pleural ganglia, connected directly with both. Originally the nervous system of the Strombacea concentrated. is less Corresponding to the elongated neck region, the parietal ganglia of Xenophora are widely separated from the pleural ganglia, the subintestinal ganglion is directly joined with the right pleural ganglion, but already in Struthiolaria the subintestinal ganglion adjoins the left pleural ganglion, connected with the right pleural ganglion by a rather short connective; the connective of the supraintestinal ganglion with the right pleural ganglion is longer. The nervous system of the Aporrhaidae and whereas it is Strombidae has greater similarity with that of Xenophora. The nervous system of the naticids is characterized by the absence of right zygoneury, whereas the supraintestinal ganglion with the left pleural ganglion by the pallial nerve; the a sometimes short, sometimes longer connective to is latter the connected ganglion has subintestinal ganglion; the connectives of the supraintestinal ganglion are longer. The ganglia of Lamellaria are much more concentrated, with double zygoneury, the supraintestinal ganglion lies over the left connectives to the supraintestinal ganglion, which pleural lies to ganglion, the the right of the remaining ganglia, are somewhat longer. In the cypraeids the supraintestinal 1571 ganglion lies close to the pleural ganglia joined with both of them, the however subintestinal ganglion a right zygoneury is is more or of the pedal ganglia, which is removed, and less distinctly sometimes incomplete; very striking is the condition Cypraeinae are produced into 2 long cords joined together by a few commissures, whereas in the Triviinae they are greatly prolonged posteriorly, but are not rope-ladder-shaped and their posterior latter ends send out nerve bundles into the foot. from Because the group, in general, appears to be more primitive than the former, which is also evident from the longer connectives of the parietal ganglia, and, because there are otherwise no closer affinities between the cypraeids and the architaenioglossans, the assumption 1056 ladder-shaped pedal cords Among Doliacea, in in this lies near that the rope- case represent a secondary structure. the cymatiids the parietal removed from the ganglia are rather pleural ganglia, the subintestinal ganglion is joined directly with both pleural ganglia, the supraintestinal ganglion is distantly connected with the left pleural ganglion by the pallial condition in the cassidids and doliids the ganglia lie more is closely together, similar, whereas nerves. The in the pirulids so that the nervous system is similar to that in the stenoglossans. Corresponding to the small size of the buccal mass, in the latter the buccal ganglia approach the cerebral ganglia and the excretory ducts of the salivary glands esophageal ring, whereas they show • still lie outside the great variation in the approach of the parietal ganglia to the pleural ganglia. For instance, in Clavatula the subintestinal as well as the supraintestinal ganglion are joined with them by distinct connectives, and in Conus the former of these is even more distantly removed, but the latter however adjoins the right pleural ganglion. The subintestinal ganglion in most cases lies between the two pleural ganglia, ganglion is with them, whereas the supraintestinal closely united joined with the right pleural ganglion sometimes by a rather long connective (Volutidae, Cancellariidae), sometimes by a short connective (Buccinidae); this may vary within the same family. All ganglia are most concentrated in olivids and marginellids. A comparison of such a nervous system with that of Haliotis shows enormous differences, although these terminal forms are connected with one another through all possible intermediate forms. Interruption of the labial commissure results in the lateral thickenings of the esophageal ring forming the cerebral ganglia, connected together only by an upper esophageal commissure. The pleural ganglia, originally adjoining the anterior ends of the pedal cords, and innervating mainly the mantle, shift away from them and adjoin the cerebral ganglia. The long pedal cords shorten gradually and lose their numerous commissures, of which the large anteriormost alone is left, likewise the epipodial nerves. In the 1572 visceral commissure develop the the former of which same the parietal ganglia and the visceral ganglion, become connected with first side through pallial the pleural ganglia of nerves, thereafter often giving rise to a connection, mainly on the right side (zygoneury). direct ganglia move distinct constrictions. Among all system of the actaeonids the opisthobranchs, the nervous shows strong Finally, being separated only by more or less close together, similarity with certain taenioglossans; the pleural ganglia are united with the cerebral ganglia, the latter are also joined together by a fine ventral commissure in addition to the upper esophageal commissure; the pedal ganglia have a strong anterior and a weak posterior commissure, the ring formed by these ganglia and their connectives surrounds the anterior part of the buccal mass, the connectives between the parietal ganglia and the cerebropleural ganglia are rather long and crossed and on either side contain a small there are more or esophageal ring pallial ganglion. less striking modifications. is retained in some Already The families, (Atyidae), Acera (Aceridae), and aplysiids it is in the pleurocoels anterior position of the whereas Haminea in displaced to the posterior of the buccal mass; the pleural ganglia often remain separate; whereas 1057 the toward the gill shifts right and then posteriorly and the mantle cavity correspondingly widens posteriorly, the supraintestinal ganglion to the right so that the crossing The ganglia contained the latter in in separated from the pleural right pallial of the visceral commissure is is pulled eliminated. pleurocoels as a rule remain by longer connectives, except the ganglia ganglion, which not seldom lies on the pleural ganglion, sometimes (Aglaja, Philine) the supraintestinal ganglion also adjoins; however, in Gastropteron all ganglia of the visceral commissure adjoin the pleural ganglia and are situated lateral to the oral tube. is Tylodina and in with it, is similar, where only the Pleurobranchaea, from this in The condition visceral ganglion remains separate, which the supraintestinal ganglion is united condition Pleurobranchus differs only by the short cerebral commissure, whereas in Umbrella and the nudibranchs all these ganglia are united with the pleural ganglia. In Petalifera and Notarchus (Aplysiidae) these visceral ganglia ventral to the esophagus. lie between the pleural ganglia, but Besides the cerebropleural and pedal ganglia the esophageal ring of sacoglossans also contains 2 or 3 visceral ganglia, the left of these begin sometimes fused with the median; they lie above the pedal ganglia. Accordingly, the nervous system in the series of opisthobranchs also shows considerable variation, the concentration of the gangliar mass has taken place in different ways. In the nudibranchs the visceral commissure is weak, situated below the esophagus, and the ganglia are aggregated 1573 above and beside the esophagus, whereas in the sacoglossans the commissure with its 2 or 3 ganglia lies above the pedal ganglia. The striking, variations the nervous system of the pulmonates are in less involving mainly the length of the connectives between the ganglia. In only one species of Chilina could an indication of the crossed commissure be demonstrated, which visceral The case, similar to that in Latia. most cases close are in commissure shortens, they remain constrictions, at rather long in this ganglia approach one another, in most cases partly but often still and because the visceral to the pedal ganglia, its least is originally independent pleural ganglia separated by short connectives some of them commissure gradually shortens until terrestrial snails, especially primitive fuse together. the The two ganglia touch. or by cerebral Among conditions are present in Carychium, the cochlicopids, the clausiliids, also the subulinids and the endodontids, although differences may occur within the same family. The nervous system of the scaphopods shows a mixture of characters of gastropods and bivalves, but has greater similarity with the latter has retained the original symmetry, as well as an uncrossed because it visceral commissure, and because the pedal ganglia are no longer rope- ladder-shaped, but knot-shaped with cerebral commissure is commissure. The short single a also very short, the initial parts of the visceral commissure on the cerebral ganglia are somewhat swollen ganglia), their connective to the pedal ganglia cerebro-pedal connectives. However, scaphopods a lingual commissure is as in is (pleural largely united with the primitive snails, retained, connectives from in it go the to the buccal ganglia, as also to the ganglia of the subradular organ, as in the loricates. here, Compared with Haliotis, a concentration has taken place evidenced by the short commissures of the cerebral and pedal ganglia, the shortening of the latter, and by the proximity of the pedal ganglia to the cerebral ganglia. 1058 Among bivalves, more or less distinct pleural ganglia are recognizable only in some nuculids, in the same position as in scaphopods. The central commissure is in most cases longer than in the latter; in the limids the ganglia are shifted far to the rear toward the ganglia of the visceral commissure, which correspond to the snails and in most cases lie parietal and visceral ganglia of the close together. Because these innervate the posterior part of the mantle along with the sense organs and muscles, they sometimes attain greater importance over the remaining ganglia. In some bivalves, lying below the cerebral ganglia there is a pair of small ganglia supplying mainly the labial palps; they correspond neither to the labial nor to the buccal ganglia of snails, but are Accessory ganglia may also otherwise occur or in the mantle margin. new in the visceral structures. commissure 1574 In the nervous system of Nautilus the three pairs of main ganglia are not separated from one another, the strand lying above the esophagus, corresponding to the cerebral ganglia, laterally divides into the anterior pedal ganglia joined together by a thinner commissure, and the posterior visceral both of which form narrow half-rings around the ganglia, esophagus; separate pleural ganglia are absent. The pharyngeal ganglia, each of which is joined with the cerebral ganglia by 2 connectives, probably correspond to the labial ganglia of snails and scaphopods, on either side they give out a connective to the buccal ganglion. The lateral of the pedal ganglia, which innervate the arms and the eye parts have to be assigned to the cerebral Both ventral half rings are fused together ganglia. tentacles, will the in dibranchiate cephalopods, whereas the innervation centers of the arms have separated and come to lie anterior to the pedal ganglia, to by strong connectives; the latter are rather which they are joined long in some decapods, but especially in the octopods they are so shortened that the ganglia fused together; in the latter the arm ganglia are joined together above the esophagus. In general, they are by a commissure also joined with the cerebral and upper buccal ganglia by connectives, which are greatly shortened in The gangliar arm nerves are connected at the base of the arms by a ring commissure. The visceral ganglia, forming the posterior the octopods. part of the ventral gangliar mass, innervate, besides the viscera, also the mantle and the form the gills; for serving the mantle muscles the mantle nerves stellate ganglia, which are joined together in some decapods by a commissure probably formed of 2 fused nerves. In this group also the most highly concentrated form of nervous system the is to be considered as most highly evolved. Some phyletic initial pits, and sense organs are also important for the recognition of the relationships among the mollusks. One may assume that because such structures are present in nautilids. in the most primitive gastropods Because indications of eyes have also been observed the juvenile stages of loricates, have become reduced as a it result is bivalves may in probable that originally present eyes of the extension of the perinotum over the head. Also, the small eyes at the ends of the labial palps in 1059 the molluscan form had simple organs of vision in the form of open some correspond to the primitive cephalic eyes. The eyes of the higher snails, and also already those of the fissurellids, turbinids, and neritaceans, are closed and contain a vitreous body, but little functional ability. On still have only the other hand, in the dibranchiate cephalopods they have attained a high level of capability; the anterior wall of the optic vesicle produces a lens and an iris is formed by a circular addition, a second circular fold forms an anterior eye chamber, fold, in which has 1575 Architeuthacea, Cirrata, and Bolitaenacea) or narrow a wide (Spirula, (Sepiacea — excluding integumental — and Spirula may be formed octopodids an eyelid opening; Loliginacea) fold. developed In contrast to these cephalic eyes, the accessory eyes various groups of mollusks are of of shell eyes the in over the closed cornea by a third of some oncidiis, and the eyes loricates, the dorsal eyes in phyletic significance, such as the little at the mantle margin of certain bivalves. An important sense organ for phylogenetic history of the the mollusks are the so-called osphradia, which are most closely associated we have no with the ctenidia. Because assuming sufficient reason for stem forms of loricates possessed a pair of ctenidia, the we many consider the sensory elevation situated beside the anal papilla in species as The homologous with the gill that cannot sense organs of the conchiferans. bands of sensory epithelium over the branchial latter originally are ganglion and the nerve in the efferent gill margin, such as those present in the zeugobranch snails and the primitive bivalves. snails that this whereas is it organ reduced at in others. Along with the of the docoglossans have become more or a pair of symmetrical is It only in the times has undergone a distinct complication, ctenidia, the osphradia less rudimentary, they form sensory elevations in the posterior part of the mantle cavity, thus indicating derivation from symmetrical zeugobranchs. Along with the osphradium of the trochaceans right ctenidium the right has become reduced, and to the extent that the left gill rachis fuses with the mantle, the osphradium also joins the latter and then a simple sensory band to the left homologous with that neritids is not as is of the and comes Because the of the trochids, also the case with the hydrocenids this is the gill. it to lie as gill of the lacks an osphradium, helicinids; associated with atrophy of the supraintestinal ganglion. The sense organ situated near the mantle is not homologous with the osphradium. is rather short, in some groups it is still margin in the cyclophorids The osphradium of ampullariids simple, in others it is bipectinate. Whereas in the more primitive taenioglossans it is in most cases a long simple band of sensory epithelium, it has become modified in a few small or large It is retained in the terrestrial assimineids and pomatiasids. groups; thus, in the solariids it consists of small radial folds forming a semicircle beside the anterior end of the it is short and broad and melanellids, is trichotropids, bipectinate; it calyptraeids, doliaceans and stenoglossans, and also triradiate form has developed in the gill, in Campanile (Cerithiidae) has assumed a similar form in naticids, in lamellariids, the triviines, remaining cypraeids. in whereas the in 1576 Whereas the gill of the actaeonids consists of a single lamella, the osphradium forms a small roundish sensory elevation; from be inferred that this gill is lamellae hanging on the underside of the mantle in and 1060 that, this may it homologous with only one of the numerous correspondingly, the osphradium is many prosobranchs, greatly shortened. It is most of the Cephalaspidea and the Anaspidea, and in Tylodina, lacking in Umbraculum, in pleurobranchids and the nudibranchs. In similar in but is Newnesia has been described as a lamellate organ below the it oxynoids as a yellowish patch or short band anterior to the somewhat uncertain whether the the gill, in seems gill. It organs of pteropods described as osphradium are homologous with those of the cephalaspideans. The in aquatic pulmonates have retained an osphradium similar to that whereas the cephalaspideans, it is lacking in the terrestrial Similar organs have nevertheless been described in forms. some of them, but homology with true osphradia is improbable. The osphradium of bivalves is a simple band of sensory epithelium on both gills, which is not specifically modified and becomes rudimentary in the septibranchs. The scaphopods have no osphradium. In Nautilus their there are 2 pairs of small sensory elevations, one of which lies between the anterior gills, the other further posteriorly near the midline of the body; an osphradium Of the statocysts and loricates, known in the dibranchiate cephalopods. should be remarked that they are lacking in the it nuculaceans they are often connected with the the in not is surface of foot by an open canal and contain sand grains; taxodonts the canal indicated only is by a strand of in tissue. other Several statoconia are found in the arcaceans, mytilaceans, and pectinaceans, in addition a larger statolith probably also is present in Saxicava, Lyonsi, Lyonsiella, and other pandoraceans; in 2 or 3 Poromya, whereas the remaining bivalves rarely the statocysts are reduced. in Among statoliths found are in most cases have one. Very the prosobranch series the have several statoconia, including also the architaenioglossans and some cerithiaceans, whereas the rest of them possess a single statolith in each statocyst. Most of the opisthobranchs primitive groups have several statoconia, but the aplysiids have one The In those statocysts statolith of the decapods the sensory epithelium forms (crista statica), each. of Nautilus are thin-walled, with numerous statoconia. one of which (the main plate) bears a 3 elevated plates statolith, whereas numerous statoconia lie on the two accessory plates; in addition, arising from the vesicle wall, there are a few peg-shaped processes (in most cases 11 or 12, 10 in Rossia, 6 in Sepiola). horseshoe-shaped crista is In the octopods only a developed, without accessory plates and statoconia, the pegs also are nearly always absent. 1577 A few, in most cases primitive, mollusks possess various epidermal some of which sense organs, the phyletic significance of The small sensory is uncertain. elevations present in the lepidopleurids in a the outer wall of the row on groove, hence on the morphologically ventral gill side of the perinotum, are very probably homologous with those on the epipodium of Haliotis; they are still retained also on the epipodial tentacles of fissurellids, and trochids, but disappear in higher snails. The lowest snails possess on either side a band of sensory epithelium, which begins near the osphradium and externally continues below the mantle around the pedal retractors (subpallial organ): such structures have been observed in Haliotis and patellids, the in fissurellids the organ is roundish sensory elevation on either side beside the osphradium. 1061 a In on the right side of the gill, below the mantle attachment, row of small sensory elevations which probably correspond to certain trochids there is a the right subpallial organ of Haliotis. arcaceans and anisomyarians, also in Neotrigonia, on either In the side of the anal papilla, there is a sensory elevation (abdominal sense organ) provided with long nonmotile cilia, the epithelium of which similar to the olfactory epithelium of vertebrates. is not known in snails; it seems doubtful whether the so-called osphradia loricates, In many at the retractors of the incurrent siphon. siphonate bivalves a sense organ of similar function phyletic uncertain for significance long time, a is corresponding organ which do have a similar position, are homologous with of The A is it. present of the nephridia, which has remained is now clear. They represent modified gonoducts, because the gonads were originally associated with the pericardium, which was only the enlarged initial part of the gonoducts. After the pericardium had separated from the gonads, so that longer in contact with the germ function. cells, the it was no gonoducts assumed excretory The nephridia thus formed completely lost their association it was more or less distinctly retained, or it could with the gonoducts, or have been secondarily restored. of the pericardium posterior In the loricates the original position the gonoducts has persisted, although they have acquired their ducts, to exit which are connected neither with the pericardium nor with the nephridia. The latter represent a longitudinal canal with branches, which communicates with the pericardium through limb and below the 7th shell duct, the outermost part of is longer, so that numerous an inner piece with the sea water by a short exit which probably has ectodermal epithelium. Both limbs are directed anteriorly and canal own anteriorly in it most cases the more or less lateral main- surpasses the renopericardial dust. In the lepidopleurids the nephridia are short and as 1578 a rule do not extend beyond the 6th shell piece, in the higher groups they are longer 2nd the and shell most cases terminate below the in Mainly piece. excretory duct, the main gives off a branch canal sometimes below 3rd, Acanthopleurinae, anterior to the the in running anteriorly above the pedal musculature and extending nearly as canal. far as the main- This form represents the highest level attained by the loricate nephridia, although also Ctyptochiton has attained a peculiar condition, wherein the posterior parts of the main-canals have become considerably widened and have united together and their anterior parts have loopshaped connections with the inner limbs. The nephridia of loricates have only minor value for the recognition of phylogenetic relationships, because they may be similar in rather different groups and may be dissimilar in related groups. The nephridia of snails are very strongly affected by the torsion of the viscera against the foot and head; the originally right nephridium enclosed anteriorly on the and is left is between the rectum and the mantle cavity separated from the digestive organs, consequently it cannot give out any outer processes and an enlargement of the glandular surface has been brought about by internal club-shaped papillae; nephridium with numerous processes infiltrates has thus acquired a 1062 condition, as is much more in contrast, the left among the viscera and favourable position. From such present in Haliotis, that of the fissurellids derived, in which the left nephridium has and has also (always?) lost the is to a be become considerably reduced connection with the pericardium, whereas the right nephridium has enormously enlarged. The nephridia of the docoglossans are very similar, except that in most cases both of them have retained their connection with the pericardium. The trochids also are related to the zeugobranchs with a spirally coiled shell, but in this group, along with reduction of the right rectum moved more left nephridium, whereas the right one receives a lesser quantity of blood; (uninary chamber). gill, the to the right, thereby leaving a large space for the On is its correspondingly restricted and apertural part is not excretory the left nephridium, a part has especially developed with canals, which open into the nephridium and are surrounded by blood lacunae (nephridial gland). The condition in the neritaceans is fundamentally different, because they no longer possess a right nephridium functioning as excretory organ; in contrast, the left nephridium is more highly developed, sometimes become branched surpassing the rectum, the papillae in most cases have folds and often the outer part is differentiated into a nonexcretory urinary Hydrocena the two parts are connected by a long loopshaped canal. The apertural part (ureter) is sometimes covered with chamber; in 1579 ectodermal glandular epithelium. The nephridium of the cocculinaceans is simple sack-shaped. A corresponding nephridium nephridial gland is also present in higher snails. all A some groups (Viviparidae, Rissoacea, absent in is Valvatidae, Pomatiasidae, Cerithiacea). In the viviparids and valvatids a long ureter developed. In Turritella, running from the nephridium to is the mantle margin there function a as an elevated ciliated groove, which is the similarly in ureter; may (?) The nephridium of communicating by a narrow solariids. ampullariids consists of 2 different parts aperture, certainly a special acquisition of the family. Like the littorinids, the strombaceans possess a nephridial gland, as also most of the higher prosobranchs. The nephridium of the doliaceans 2 into right which parts, identical. However, in Dolium are divided by the rectum is almost completely separated but in naticids there are 2 lobes differing in structure, the one showing a network of lamellae, while the left which one, adjoins the nephridial gland, having papillae similar to those of the left kidney of Haliotis. In cypraeids the right part one is similar, the other is occupied by numerous parallel lamellae and is nephridial gland. In stenoglossans also 2 lobes are separated from the more or less distinctly separated and unequally developed; designated as the highest stage condition in muricids and buccinids, where the left among lamella with secondary lamellae which infiltrate the is lobe forms a marginal the lobules of the right lobe. The nephridium of pericardium and the the Cephalaspidea lies in the mantle between the gill, as a compressed sack with internal folds, without a separate ureter and without a nephridial gland, similar in other shelled groups; in the shell-less forms renopericardial duct Duvauceliidae, (Aeolidiidae, The kidney 1063 is is sometimes more or Polyceridae, Elysiidae); sack, it which less originally simple, The long (Pleurobranchidae, Dendronotidae), sometimes Elysia there are several in is displaced into the body. may such very short connections. in various groups of nudibranchs give out a few or numerous processes, similar to the right nephridium of Haliotis and both nephridia of The nephridium of loricates. the most primitive pulmonates (Ellobiidae) is very similar to that of the Cephalaspidea: a sack lying in the mantle beside and anterior to the pericardium, internally with a few folds, anteriorly opening into the mantle cavity with a papilla, without ureter (Fig. 894). In the series part has of basommatophorans become lengthened and although folds are present in in it in most cases the anterior an excretory epithelium its interior; this part is to is absent, be considered as the urinary chamber, which represents a part of the true kidney chamber. 1580 Fig. Roof of 894. the mantle cavity of Marinula juanensis N. Odhner. c, heart; g, pallial gland; n, kidney; r, rectum (after Odhner). In the stylommatophorans, as a rule, a tube, known as ureter, has separated from the opening of the kidney chamber onwards on the underside of the mantle, which transports the excreted materials toward is represented in a few the opening of the lung cavity. Such a ureter primitive groups only by a posteriorly running ciliated groove, whereas, basommatophorans, the kidney sack extends far forward, where A distinct boundary between the latter and an (ectodermal) ureter constricted from the mantle is often formed by a pore, corresponding to the original opening of the nephridium, but as in the it serves as urinary chamber. not readily clear whether it is a kidney chamber or a where the boundary between the two lies; thus in the athoracophorids it seems uncertain whether the long many-limbed ureter occasionally it is ureter, or as to is entirely or partly of ectodermal origin. In the oncidiids the kidney sack opens through a short and very narrow duct into a papilla situated in a this process thus represents a ureter. The short process of the anus; condition in the soleoliferans, which lack a lung cavity is to understand. In the rathouisiids the three-limbed ureter a narrow terminal tube on the right side more difficult opens through between the foot and notum, 1581 rather far anteriorly together with the rectum, into a slight depression above the ? genital opening, separated from the pore by latter a small fold; a not present at the beginning of this duct, and the ventral part of is the terminal limb surrounded by a subepithelial is Vaginina, which In is mass. cell among probably the most primitive form the vaginulids, the kidney sack and the three-limbed ureter are very similar, but the rectum and the ureter extend further to the back within notum, the former opening externally with a wide aperture of the posterior of the tip foot, the latter with a the to the right narrow opening in the midline of the animal posterior to the foot; soon after leaving the body cavity, that intestine is, in the region where they open in the rathouisiids, the upwardly gives out a short process, and the ureter gives out another process, opening into the former with a narrow aperture. This 1064 condition thus has a similarity to the kidney opening of oncidiids, if the intestinal process latter. It may of Vaginina is compared with the gut opening of the thus be concluded that the three-limbed ureter of Vaginina and the remaining vaginulids actually represents a urinary chamber, evidently a difficulty posed by the presence of the subepithelial gland is should this be regarded as ectodermal, although represent a homologue of rather, this aggregation of the cells it probably does not hypobranchial gland of cephalaspids; may represent a blood gland. At any rate, the ureter situated posterior to this connection, which a is rathouisiids, to is still be considered as a secondary acquisition; in intestine running within the notum appears most Vaginula species the intestine to Vaginina connected with the rectum by a few tubules arising from the and opening into the ureter through narrow pores. Hence, in also present in few other vaginulids (Pseudoveronicella), has, when compared in this it latter case the similar to a cloaca, whereas and the ureter unite only at their ends. In the shell-bearing is variable, sometimes in the vicinity stylommatophorans the form of the kidney sack short, sometimes more or less long, the pore lying of the pericardium and the pulmonary vein. From ureter as a rule runs backward on the right it the margin of the kidney sack and then often more or less far to the front beside the rectum; this latter part is designated a secondary ureter. It has probably developed in various groups which are not closely related with one another, so that its presence alone has no great phyletic significance, although compared to its absence it generally has to be seen as a wall of the ureter is more advanced condition. The sometimes smooth, sometimes more or less richly folded. The scaphopods possess nephridia, which a pair of symmetrical, are connected neither with somewhat lobed one another nor with the 1582 pericardium and open into the mantle cavity beside the anus; they are primitive, the absence of pericardial ducts alone is a secondarily acquired character. The nephridia of more ancient bivalves the show also primitive and zeugobranch snails, the original form seems to comprise 2 more or less folded and entirely separated sacks, communicating with the pericardium through one ciliated Similar to conditions. in the scaphopods canal each, and opening externally without distinct ureters; an indication of a connection with the gonoducts open may be Solenomya these The nephridia of the present, in into the anterior parts of the proximal ducts. nuculaceans appears as two-limbed tubes, connected to one another and opening externally together with the gonoducts, and this urogenital cloaca is in most cases connected with the proximal part by a short canal or a perforation of the walls. The nephridia of the arcaceans, mytilaceans, and trigoniids are sack-shaped, separated from one another, and open together with or beside the gonoducts. In the pectinids they have a short proximal and a sack-shaped distal limb, the latter being connected and receiving the openings of the gonoducts. In limids these open in the ends of the proximal limbs, similarly in anomiids. The form and location of the openings as well as their positional relationship with other organs are and variable of little phyletic nevertheless significance, the eulamellibranchiates uniformly have the nephridia situated posterior to the pericardium and. in lacking any connection with the gonoducts. Just 1065 as nuculaceans differ from arcaceans because of the loop-shaped nephridia, those of the unionaceans, in contrast to the trigonaceans, have assumed a loop shape and beside the posterior bend the proximal limb forms folds covered with excretory epithelium, the the other side. The nephridia of shaped proximal and lateral distal limb connected with that of the corbiculids also consist of an arch- and an additional distal limb connected with form of the nephridia of sphaeriids is to be derived, with a complicated loop formation (Fig. 895). In most heterodonts, as well as in the Anomalodemata, the distal limbs are sackshaped and connected to one another, as also in the pholadids, whereas that of the opposite side; from this the in the teredinids, the nephridia are elongated and are reflected anteriorly over the pericardium, so that both limbs merge into one another behind the adductor muscle and the internal and external openings are posterior in position; a connection between the two nephridia is here lacking. In the cephalopods also the nephridia represent sack-shaped cavities, of which in Nautilus, corresponding to the 2 pairs of gills, there are 4, the posterior of these being homologous with those of other mollusks. Because their excretory parts are developed at the afferent branchial vessels, the division of the gills into two also resulted in a division of the kidney 1583 Fig. 895. Kidney of Pisidium henslowanum (Sheppard) (after Odhner). sacks. A direct communication with the pericardium is not present, but the posterior larger sacks open into the mantle cavity immediately beside the exit ducts of the pericardium, so that it may be assumed that these have only secondarily detached from the kidney sacks. The dibranchiate cephalopods have one pair of nephridia, which in octopods remain separated from one another and possess each an accessory chamber, with decapods both nephridia are united without another, and a wide dorsal dilatation may develop, which which they stand in open connection. In the extends posteriorly below the shell; this contains various veins with glandular appendages. The exit ducts of the pericardium open into the of the nephridial ducts, which open beside the anal papilla. Because the pericardium of mollusks has arisen from enlarged initial parts initial parts of the gonoducts, originally paired, consisted of 2 another. has still It may in so primitive in is to be assumed like the gonads, these were that initially the pericardium also which however almost always fused with one seem doubtful whether the originally paired condition parts, also maintained genus Area, of it and because, itself in any group; nevertheless the species of the which alone 2 completely separated pericardia occur, are their entire make-up, that one can assume it to be also this character as well as the fact that the two nephridia are entirely separated, whereas in the nuculaceans and most of the bivalves they are interconnected. As a result of misinterpretation of homologous parts, the pericardium together with the nephridia of mollusks, was declared equivalent to the body cavity and the segmental organs of 1066 annelids, but it cannot be doubted that the molluscan nephridia correspond to primary gonoducts, which have disappeared in annelids, and that in addition the body cavity 1584 (coelom) does not agree with the pericardium of mollusks. As a rule the among latter is no larger than what the heart needs snails has attained an extrordinary extension in Septaria, stretching out it from the into the posterior part of the animal between the viscera up lies, to a greater extent, still enlarged; to the right that it between the gonad and gonoduct which that the left side, the where the heart side. In a similar fashion, but pericardium of Nautilus has become the and one can assume from ectoderm, so for its expansion; gonad seems pushed with one of is its to lie in the body lobes formed largely or completely cavity, which represents an enlarged pericardium and extends between the viscera; by means of the suspensory band of the gonad, an incomplete septum is formed between the body cavity and the true pericardium, the latter of which encloses the heart with The decapods 4 its auricles. wide body also have a cavity, which may sometimes (cranchiids) extend very far anteriorly. In octopods, on the other hand, the body cavity is considerably restricted and the true pericardium is reduced, the heart being enclosed only by a connective tissue capsule; by a pair of canals part is connected the gonodal to pouches, which contain the glandular appendages of the are joined to the nephridia by The gonads of mollusks 2 bottle-shaped gill hearts and ciliated funnels. and with are originally paired, symmetrical, separate sexes. Their original position anterior to the pericardium has been retained but they are almost always fused with one in the loricates, another, remaining separate only in Nuttalochiton, so that here they are The gonoducts similar to the solenogasters. in all loricates are entirely separated from the pericardium and the nephridia and open into the gill groove anterior to these. They consist of an inner part which derives from the gonad, and an outer part formed by ectoderm, and in the by glandular epithelium and ? this part is in at is most cases much larger than the inner, but in Lepidopleurus the latter forms the entire portion lying within the visceral cavity. assume that this condition is the The gonad of loricates, it the snails more always single; because, in contrast to the is it with only one of the two original gonads, the lies on the right In right. patellaceans, and trochaceans) nephridium, opening as One can original. always has only a single exit duct, after torsion covered times presenting an enlargement; it it is left probably homologous one, which however the primitive groups (zeugobranchs, still shows a does into its distinct connection to the terminal part or in renopericardial duct. At the opening into the mantle cavity, in the the ? an They are ectodermal glandular duct develops. Considerably altered are the conditions simplest in hydrocenids. In the ? in the neritaceans. sex the oviduct gradually becomes 1585 glandular and opens into another duct which is surrounded by subepithelial glandular masses and anteriorly opens into the mantle cavity beside the anus; beside the opening on the oviduct into this duct there are also openings of 3 other tubes; one of these 2nd 1067 which be called bursa copulatrix and opens into dorsal side of the to is glandular duct; the 3rd a duct, a blind-sack-shaped gland, the is an anteriorly narrow, posteriorly somewhat widened blind sack, is in the posterior continuation is, of the glandular wide tube which through a narrower terminal opening fairly passes into a sack-shaped cavity, the epithelium of which consists of glandular cells without supporting a homologue of the it is right cells. close to consider this sack is It kidney of trochaceans, because like the latter, connected with the glandular duct by a direct passage. However, must be emphasized that a connection to the pericardium has not proven and that the oviduct does not open into connection it been sack, but that a this effected only through exit ducts which are covered with is ectodermal glandular epithelium. From this condition the structure in the helicinids can be derived without difficulty, if one assumes that the bursa copulatrix has acquired a separate opening into the mantle cavity, which lies within the interior, and that it more or duct by an in most cases short duct; attached to this and vesicle at which sack, its posterior end there view of in its less deeply has remained connected with the glandular is a more or may be less well position and the nature of its a seminal developed epithelium corresponds with the sack of Hydrocena. The conditions more difficult to understand. As a by spermatophores, the bursa copulatrix has become greatly enlarged and its opening has moved forward beside that of a result in the neritids are fertilization of the glandular duct (ootype), the connecting duct with the in helicinids, is also more or less lengthened rule has a receptaculum seminis. The oviduct in is in this case a short most cases communicates with the pericardium through a ciliated funnel. there latter, and complicated, and as a homologue of the sack It is uncertain whether lying at the end of the glandular duct of helicinids, such as the peculiarly lobed part of the connecting duct between the ootype and spermatophore sack of Nerita. In some groups even to the a third opening of a duct has been formed, leading receptaculum seminis. It is evident that such a condition most divergent from the normal than The duct, <? that of the The d organs of found is much hydrocenids. apparatus of Hydrocena consists of a strongly coiled sperm which leads into a wide glandular tube; posteriorly the glandular blind sack, and another one opens into is littoral at the it near its latter has a anterior end. the helicinids are similar; in the neritids a lobed prostate opening of the sperm duct into the spermatophore gland, 1586 and beside the is cephalic tentacle a lobe-shaped copulatory organ right developed. There probably no indication of the is right kidney remaining. The gonoducts of the Cocculinacea are very simple; the hermaphroditic gland has a single exit duct, the epithelium of which consists of glandular and supporting cells, it opens into the mantle cavity near the anus; a variously shaped depression of the mantle cavity serves as bursa copulatrix. At the in sometimes a d copulatory organ right tentacle Bathysciadium pacificum Dall of which is this is more developed; and presents an enlargement before forming partly glandular a narrow and long terminal tubule. The the gland may be appears as a tube, the inner epithelium d duct of strongly developed and near Titiscania sperm duct runs spherical seminal vesicles; the coiled is opening its simple, only lie about 12 to a small elevation behind the right eye. The d gonoducts of the higher prosobranches similar in structure; 1068 often a receptaculum seminis is opening of the oviduct into the glandular mass and gland is are essentially present near the opening the at its connected to a blind sack, known as bursa copulatrix. In Littorina a connection of the pericardium to the end of the oviduct has been demonstrated and it is possible that such a connection also present in other groups, because \X it is is it is is developed in ? calyptraeids, whereas absent in the preceding d gonoduct and also in the ? Capulus. Thus uncertain whether such a gonopericardial duct always to be is regarded as an inheritance of zeugobranchs and trochaceans or sometimes as a secondary acquisition. The same applies to the question whether the receptaculum seminis represents a rudiment of the right kidney. Such an interpretation is possible in cases like Littorina, structure and is where a sack-shaped it is connected to the pericardium; but in other cases be absent or cannot be interpreted in this Pomatias the oviduct median is widened in in Pila (Ampullariidae) the oviduct its way because of part forms several its it may position. In and receives the sperm; spiral coils within a bean- shaped body formed of connective tissue. In Calyptraea however a bundle of vesicles separates from the posterior end of the "uterus," similarly in Crepidula; and in are present, similarly in different nature, Marsenina and lamellarines several vesicles These are apparently structures of a Trivia. which have possibly arisen in different not always of equal value. These conditions are still groups and being poorly known among higher prosobranchs; in Oliva the receptaculum seminis represents a coiled, tube-shaped appendicular structure with extensions, surrounded somewhat by a lateral sack-shaped thick fibrous connective tissue layer, hence similar to that in Pila; in Concholepas the oviduct in the middle has a thick-walled sack-like bean-shaped extension, perhaps representing 1587 a receptaculum; in Melo, at the end of the oviduct, there a fairly large is sack-shaped appendage with thin walls of doubtful function. The glandular mass into which the oviduct opens, most cases in considered as the uterus, consists as a rule of a proximal albumen gland and following is added. a capsule- or shell-gland, to which at times a jelly gland it The may be sometimes species closely related in latter developed, sometimes absent; thus in Littorina rudis a non-glandular brood space differences, present in is which in These glands also show other plate. its most cases have only phyletic significance. little The anterior part of the uterus sometimes has a long cleft-shaped opening (cyclophorids, pomatiasids), but in most cases anterior opening. A tube-shaped with an is it separate vagina with a bursa is not seldom absent but frequently the anterior part of the glandular tube In Strombus the glandular tube shaped; opening into it is very long, posteriorly blind-sack- is along with the oviduct is a receptaculum seminis and a thin glandular tube; from the outer opening a of the to the anterior part Some considered as the more weakly developed. vagina, where the glands are absent or they are foot; the ? groove runs ciliated organs of heteropods are similar. melaniids show brood care; in Tanganyicia a brood pouch opening below the The sperm duct A differences. is widened sometimes present is formed right eye. some usually long and coiled, but there are part, which serves as vesicula seminalis, sometimes in the proximal, in the distal is portion. A prostate can be developed as an open glandular groove or as a closed tube; in this respect species of the The 1069 is cf copulatory organ shows developed at the closed, rather short right tentacle; same groups can be different. some peculiarities. In viviparids it is connected with the sperm duct which passes and a thin-walled terminal part; it it by a testis into a thick-walled expansion has certain similarity with that of Bathysciadium. The penis of Cyclophorus is cone-shaped, attached below the right tentacle, connected with the genital opening through a seminal groove and supplied by a nerve from the right pleural ganglion. situated behind the right tentacle is present Trichotropidae, Capulidae and Calyptraeidae, in the the in first it is penis of these families with closed sperm duct, in the others with a sperm groove. pomatiasids A Vanikoridae, In the located rather far to the near on the right side and innervated from the subintestinal ganglion; the sperm duct a pear-shaped prostate. The cf is copulatory organ of ampullariids unique, lying on the inner side of the mantle margin; it is is closed, with is variably strong developed and as a rule consists of a more or less long, thin process with a sperm groove, at the base of the process a tubercle or a lobe being 1588 present; the process is surrounded sheath-like by a rather thick extension with a groove. The condition in the hydrobiids the penis groups still it situated in the neck region; is its is also peculiar, for here shape is varied, leaf-shaped, in others with a basal process. is appears uncertain, in Pseudocyclotus, where the penis is some in innervation Its also located at the neck, the nerve appears to arise from the connective between the and pedal ganglion, but close below the cerebral. In most of the taenio- and stenoglossans the penis is located on the right side not far from the right tentacle, more seldom farther away from it, and is right cerebral innervated from the right pedal ganglion. In view of the condition in Pseudocyclotus, it seems possible innervation from the pedal that the ganglion is not to be regarded as fundamentally different; thus in the case of Oliva it has been stated that the nerve arises at the place where the right pedal ganglion merges into the cerebral ganglion. Nevertheless, it can be considered as certain that mainly in the lower groups of the prosobranchs a d" copulatory organ has developed in various ways. It is absent in the Cerithiacea and Ptenoglossa. Seldom has hermaphroditism developed in the series of prosobranchs. Whereas in the cocculinaceans, and probably in the pyramidellids, the gonoduct remains simple, times complications appear in various ways, at part has developed alongside of a complete in which the is the case in the valvatids. cf a similarly formed appendage of the copulatrix, part, as The hermaphroditic duct divides and both branches bear appendicular organs, the prostate sack; 9 and another one a shell ? a club-shaped blind is part Among gland. may be a bursa the lamellariids, in lamellariines the sexes are separate, in both of the other subfamilies they combined and their form shows considerable variability and species, Marsenina is most similar to Lamellaria. are In a similar fashion the pulmonates developed. In in the genera hermaphroditism of the opisthobranchs and Actaeon there is a glandular duct (uterus) opening into the mantle cavity, and a bursa copulatrix, as well as a closed sperm duct and a non-retractile penis lying on the right side, similar to that in some prosobranchs, with sexes are here combined; the penis, as in 1070 from the right pedal ganglion. The the only differences that both all opisthobranchs, ringiculids a closed sperm duct but a retractile penis; but in as well as anaspideans and pteropods, opening by a ciliated canal, sometimes it it is is innervated and hydatinids also have all other cephalaspideans connected to the genital has a prostate. The form of the gonoducts and the appendicular glands shows considerable differences, at the sperm duct in most cases a vesicula seminalis is developed and on the outer part of the stalk of the bursa copulatrix a sack-shaped expansion may be present, but an equivalent of the receptaculum seminis of 1589 prosobranchs appears always to be absent. Haminea agrees with Acera and the aplysiids having a special nidamental gland in terminal at the part of the gonoduct. The sacoglossans have oxynoids and in the a closed sperm duct, which partly glandular is connected with a large seminal vesicle, whereas is The glands the vagina receives the duct of a double bursa copulatrix. in this family are massive; in the shell-less sacoglossans the hermaphroditic gland and the albumen gland are branched, and the duct divides in 9 some genera and opens with an anterior exit duct of the mucus gland (ootype) and with a posterior vagina, which is connected with a larger spherical bursa copulatrix; accordingly the reproductive apparatus here is very complicated. In the notaspideans the approached the sperm duct opening, which $ also closed is and the penis has occasionally divided is into the anterior vagina and the posterior opening of the mucus gland, but the ? duct is undivided; Next prostate. to it has a bursa copulatrix, and the sperm duct has a these stand the nudibranchs, among which there are certain differences that must be noted for systematics. The of the primitive pulmonates genital apparatus of the cephalaspideans, here again the genital found similar to that is retractile penis is connected to the opening only through a sperm groove. Variations are already in the ellobiids, in united up to its which the hermaphroditic duct opening, sometimes it is times remains at divided, to a varying extent, into a female and a male duct, opening at times together, at times separately; a bursa copulatrix in most cases is the opening, but in Tralia and Melampus its is attached not far from is rather far away from innervation from the right cerebral ganglion in pulmonates be explained by a displacement along the pedal connective. sperm duct is in most cases present end of the penis. to the inner and it. The very probably homologous with that of the bpisthobranchs, retractile penis is hence long-stalked and this also is the case at the penis, In Otina the is to In ellobiids a extending from the groove sperm duct is already closed, of most basommatophorans. In Siphonaria the penis opens together with the genital duct without an inner sperm duct, a prostate is Amphibola present; in but an inner sperm duct the proximal is also both openings lie close together, present, as is also a long and thin prostate end of the penis, whereas a bursa copulatrix Gadinia has separate openings and a closed sperm duct; gland lying beside the ? shell gland duct serves as basommatophorans the is prostate. similar. at the is at absent. in this case a opening of the hermaphroditic The condition in the hygrophilic These are often expansions present at the hermaphroditic duct which have been called vesiculae seminales or fertilization pouch and are probably not always homologous; also 1590 improbable 1071 from the may be a is homology with receptaculum seminis arising the kidney in some prosobranchs, even though their location right similar. Because of the separation of the d" copulatory organ from the 9 opening, the oncidiids approach the basommatophorans; however, this separation has here reached its peak, wherein the posteriorly with the lung and rectum, whereas the anteriorly, ? duct has shifted d duct has shifted opening beside the right tentacle. The hermaphroditic duct receives the exit ducts of albumen and mucus glands and (spiral glands) has a sack-shaped or internally folded appendage of variable size, probably a prostate; after separation of the sperm duct from the oviduct, the latter has a spherical bursa copulatrix, whereas the former runs under The d copulatory apparatus is very some species a penis gland the skin forward to the penis. differently developed within the family; in is developed, probably from a blind sack of the penis sheath, similar to the prostate of Amphibola, sometimes of considerable size, terminally with a spine. In the soleoliferans also the genital openings are another; in the rathouisiids the female opening lies away from on the below the anus. The gonoduct has some resemblance with oncidiids, copulatrix, while a prostate is of present at the beginning of the sperm duct. apparatus, which lies at the head, of the oncidiids in having a more or which opens side that receives the exit duct of a large gland and has bursa it The d copulatory that the one right less large is also similar to tube-shaped gland, into the penis sheath; a similar gland is often also developed The opening of the ? genital duct of vaginulids lies on the underside of the notum in about the middle of the right side, the fertilization pouch is represented by a widening of the hermaphroditic duct, the oviduct is long and coiled, the sperm duct in most cases on the left side. provided with a club-shaped prostate and directly connected with the bursa copulatrix through a short tube (canalis junctor). The penis of Vaginina has only slightly developed glandular tubes, which open into its posterior end; in the remaining genera these tubes are much more strongly developed and open into a special cone-shaped process of the penis pouch, which In is all is called a stimulatory structure. remaining groups of land snails the opening of the penis sack united with the $ opening or d ducts are internal folds; more or is at least very close to it. The ? and and are separated only by a pair of the ? part receives the secretion of the albumen gland and less united wall is often folded and glandular, it sometimes serves as uterus which the eggs develop into embryos. The bursa copulatrix, which variable in size, sometimes with a short, sometimes long stalk, has its in is in 1591 some groups acquired a blind sack on the stalk for the reception of a spermatophore. The <$ part is glandular (prostate) and then runs as a sperm duct to the penis; also associated with at its are often glands (epiphallus) and it opening into the penis a thin tube (flagellum). Like these some groups stimulatory organs are developed, in the gland" (glandula amatoria) often with dagger-like tip, parts, jn form of a "love or as a calcareous spine (Gastrodontinae), or love dart in association with simple or a multipartite gland (Fruticicolidae, Helicidae). first The terminology of homologous parts in the literature and also in the two parts of this handbook lis not uniform; the copulation pouch (bursa copulatrix) principally has often been called the receptaculum seminis; the fertilization pouch, not seldom developed on the hermaphroditic duct, very different from is groups are to Similar structures developed in various it. be considered analogous, not homologous, even if they have received the same designation. The conditions unisexual gonad in its is in Siphonodentalium also own exit duct; scaphopods are uncommonly simple: the the unpaired, in Dentalium lying only on the dorsal side, dissolution of the wall it of the mantle, in ventral part maturity at it releases its germ and the gonad, as well as its mode of position in the posterior part of the body, and especially the release, are not to after through the kidney into cells The unpaired nature of the mantle cavity. does not have it fuses with the right kidney be regarded as primitive. The gonads of the bivalves paired are symmetrical, originally unisexual and lying in the visceral sack, rarely extending more or less far into the mantle; their short and simple kidneys or near them; some in kidneys, through which they empty into the in Solenomya and however it in the pectinaceans, to At any show only common openings rate, of primitive into the cavity. This is the case which the anomiids are this is to close; be viewed as an and mytilaceans, as well as the for the kidneys and gonoducts. the gonoducts of the bivalves correspond only to that part which snails, kidney or into its is formed from the gonad and opens into the connection with the pericardium, so that as a rule they have no ectodermal part, just Hermaphroditism has arisen families, gill seems somewhat doubtful whether original condition, because the taxodonts trigoniids open together with the exit ducts primitive groups they open sometimes only in as they always in lack copulatory organs. various groups, sometimes single genera or species; even in in entire species which are otherwise unisexual, hermaphroditism may develop under special circumstances; all Anomalodesmata are hermaphroditic, with the exception of Cuspidaria. 1592 The gonad of cephalopods always unified and the sexes are is separate; because the gonoducts are originally paired, whether the gonad corresponds have fused together as in to the most of the sum of it may be questioned the paired anlagen, which only to one of them, loricates, or The genital sack containing the gonad opens in Nautilus into the body cavity, but opposite to this opening lies the beginning of the gonoduct which receives the germ cells, without itself being situated in the body cavity. The left gonoduct the other having completely disappeared. has no connection with the gonad and represents a pear-shaped vesicle opening into the mantle in the outer part, The oviduct cavity. and opens at the is short and wide, glandular base of the mantle cavity. The sperm duct forms a spermatophore gland, then a spermatophore sack, and ends a penis-like process posterior to the funnel in the in "spadix" side, is employed cavity. gill for copulation; this is a group of 4 cirri of The one body which represent the ventral part of the inner system and are peculiarly modified. gonoducts are in most cases paired, but in In the dibranchiates the ? the Sepiacea and Loliginacea, and also in the cirrate octopods, the right oviduct has one; 1073 its become reduced, terminal part in Pterygioteuthis in contrast The d gonoduct 1 glandular. is Calliteuthis, otherwise only the left and coiled, followed by a one trilobate is is it the left is paired only in retained. Its initial part is narrow spermatophore gland, thereafter a "Rangir gland" and finally the spermatophore sack (Needham's pouch). In the decapods the gonoduct communicates with a pouch-like depression of the epidermis through a narrow ciliated canal arising between the two glands; the glands are enclosed in this depression; in the Architeuthacea it is are anteriorly open, in others more divergent; it forms a closed capsule. The octopods here the end of the gonoduct forms a penis-like a gland which process, on which there is but a genital pouch lacking. is is sometimes strongly developed, For the transfer of the spermatophores to the female, use a rule of a more or less Nothing a known about is made as modified arm, or more rarely a pair of arms. this in some genera, as for instance in most of the Architeuthacea and the cirrates. In decapods, in most cases one of the ventral arms is hectocotylized, rarely both of them (Spirula, Idiosepius, Todaropsis), in sepiolids and histioteuthids on the other hand the dorsal arms are hectocotylized. The modification of a 3rd arm of octopods has taken place in a different way, in the Octopodacea by the development of a spoon-shaped terminal part, in elongation and detachment from the Argonautacea by a considerable body in the mature state. 1593 Outline of the Phylogeny of the Mollusks There is no doubt that the animals. shell-less constituted, In mollusks developed in Precambrian times from order to determine how animals were these one can draw conclusions through a comparison of some living animals pertinent to this problem. Among still these, principally the Solenogastres are important, which together with the loricates have been grouped as Amphineura, and in comparison with the latter even have been considered by Pelseneer as secondarily simplified, although viewpoint untenable and has been given up is The Solenogastres are this at present. completely shell-less and their regular dermomuscular tube proves that they could not have descended from shelled animals. They are in most cases cylindrical covered with a more embedded calcareous needle- or scale-shaped mouth and anus in most cases groove, into which subepithelial glands open. The or less strong cuticula with bodies; but running ventrally between the there is a ciliated mouth opening cirri, often lies at the base of an atrium provided with sensory occasionally separated from the which may contain gills. the anus also lies in a cavity latter; The nervous system consists of an indistinctly paired upper esophageal ganglion and 4 ganglionic longitudinal cords, of which one pair is positioned ventrally and the other laterally; as a rule they are connected by several transverse commissures; in addition, a pair of buccal ganglia radula, 1074 which is is in The foregut has various glands and often a most cases small and without a uniform basal present. membrane. The midgut runs as a straight tube toward the rear, not seldom with regular lateral expansions. The heart consists of a posterior auricle and anterior ventricle; true blood vessels are not developed; the space between the dorsal body wall and the gonads serves as an aorta and ventrally, above the ventral groove, there is an incompletely delimited sinus. The gonads comprise a pair of elongated sacks lying side by side, rarely fused with one another, or as of pouches with longitudinal series ducts lying between the intestinal sacks; the are widened and fused with one another to initial parts of the exit ducts form a space which surrounds the heart and thus simultaneously serves as pericardium and uterus. The following part of the exit ducts recurves anteriorly, then forms evaginations serving as sperm containers and turns backward, opening into the below the anus; this terminal part is glandular and often posterior cavity unpaired, the ducts fusing together before their opening. Some of these conditions are characteristics which the Solenogastres share with the "worms," and which distinguish them from mollusks, such as the cylindrical form, the absence of a shell, the regular dermomuscular tube, the elongated midgut, the long nerve cords, the gonoducts with their 1594 widening serving as pericardium, and the cloacal chamber; hence the Solenogastres are to be excluded from the mollusks. The They agree with them loricates are closest to the Solenogastres. mainly in the basic form of the nervous system with the 4 longitudinal cords and in the position of gonads under the dorsal body wall and anterior to the pericardium, as well as in the possession of a cuticula with calcareous bodies. the calcareous embeddings However, there are important differences, foremost which has developed as separated calcareous shell one behind the other; these remained in the cuticula, lying joined to one another by muscle bundles which have separated from the was possible. In the region of the embedded in the cuticula disappeared and extended to the surface (aesthetes). The shell parts dermomuscular tube, so that inrolling shell, the calcareous structures the epithelial papillae then formed 8 entirely external plates, which at the attachments of the connecting muscle bundles and the musculature of the perinotum, developed projecting margins and correlated differentiations in the structure of the plates. Because of the formation of the covered the entire dorsal at the fold was which surrounds the formed the originally side, which previously body margin. It ends shell, the cuticula, restricted to the gill groove of the loricates. This fold margin of the body and probably terminated lateral anteriorly at the head; gradually a muscular bulge developed above it, assumed the shape of an edge which then formed a secondary body margin and closed itself in the form of a ring anteriorly above the head as well as posteriorly above the anus. and this From loricates the fact that the cuticula covered only the dorsal side of the and left the ventral side free, probability that the turbellarians. originally Besides Hence, more this, loricates it will flattened the derive it may be deduced from flat with much animals similar to be assumed that the Solenogastres too were and protected by a cuticula only dorsally. common ancestral forms probably possessed longer midgut processes, between which muscle bands descended; the midgut glands of the loricates processes. The may be considered to have been desired from such foot of the loricates derived from the ventral dermomuscular tube and the transverse muscles, the sole corresponding to the ciliated groove of the Solenogastres. Because the formation of the anterior (atrium) and the cloaca of the Solenogastres probably 1075 of the cuticularization of the ventral in the loricates. The gill is pit a consequence side, these invaginations are lacking groove has formed through the development of the foot and the perinotum. The with those of Solenogastres. gills lying within it are not homologous 1595 While the 4 ganglionic longitudinal cords in both animal groups are homology does not seem doubtful, the anterior parts so similar that their of the nervous system show considerable differences. The Solenogastres have a pair of adjacent upper esophageal ganglia and a pair, of small buccal ganglia, the loricates on the other hand have an esophageal ring with lateral swellings and 2 pairs of buccal ganglia, which also form an esophageal ring; in addition they have the ganglia of the subradular sense organ which lacking in the Solenogastres. is of the parts In the latter the anterior cords are often more or less swollen and these lateral swellings correspond to those of the esophageal ring of the loricates; other differences are due to the development of the perinotum. The digestive organs of the two groups are considerably different. The radula which is present in several genera of the Solenogastres never attains a such a size as in much loricates. Moreover, in the latter has attained it higher condition, not only by the development of a basal membrane and a complicated musculature, but also by the differentiation of the plates in the individual rows, mainly of the large hooked plates with especially hardened and detachable cutting edges, and the reduction of the cutting edges of the marginal plates. The esophageal glands of the Solenogastres are various, and homologous glands are lacking in the loricates. The alternations great: with the the long, open which the midgut has undergone are very (liver), and sack-shaped anterior glands, the midgut gland more or less coiled intestine into a cloaca. The of the loricates; the latter heart of the loricates can be derived does not from that of the Solenogastres, perhaps by reduction of the simple posterior auricle and the new development of 2 development of gills. lateral auricles in connection with the The haemocoel of the Solenogastres is at a very low stage, and in loricates a complicated vascular system has developed. Whereas the pericardium of the Solenogastres is a part of the gonoducts, in the loricates it has separated from the latter and its exit ducts have assumed excretory function; the gonads, on the other hand, which in most case have fused together, have received their Through all own secondary these differences, especially the shell, the gonoducts. foot, the reduction of the complete dermomuscular tube and the stronger transverse musculature, the perinotum, the fore- and midgut glands and the coiled intestine, the separation of the pericardium from the gonads, also the first acquired the essential loricates begins with forms that did not yet paired auricles of the heart, the loricates features of the molluscan type. The phylogeny of the possess insertion margins, so that the shell was entirely external except for 2nd to 8th pieces; probably the surface of the most primitive forms had only minute warts, which corresponded to the small apophyses of the 1596 and the narrow perinotum was covered with minute aesthetes, among which were scattered outer wall of the gill small needle- or club-shaped bodies. scales, On Originally the hooked plate probably had a tricuspid cutting edge. 1076 nephridia and the retained in gill rows were short. The These characters have been the group of Leptochiton, to which are joined the other of Lepidopleurus sections the groove there was a row of sensory elevations. The rasping . plates in genus show this considerable variability. Hanleya has larger apophyses and a smooth insertion margin at the anterior margin, also a stronger perinotum. A very Hemiarthrum, with smooth insertion margins on both end pieces, with groups of longer needles on the fairly strong perinotum at the margin of the anteriormost shell piece and between the following pieces; the radula with tricuspid hooked plate and remarkable transitional form is notched cutting edge of the lateral Tonicella. these and The condition all plate is very similar to that in attained in the Lepidochitonidae distinguishes other loricates from the lepidopleurids: the development of incised insertion margins on distinctly granulated; the all shell perinotum pieces. The like that surface is more or less of the lepidopleurids with minute scales or needles and small groups of larger needles; the cutting edge of the hooked plate of the radula is tricuspid, that of the lateral plate in most cases notched or comb-shaped. Nuttalochiton is a remarkable is sculptured with ribs or rows of warts and has group, the shell of which connected apophyses and which differs from all by the paired others gonads, apparently a feature of very primitive organization, but this does not put the genus at the beginning of the phyletic development. At the same time it indeed shows striking affinities with various groups of loricates. The Callochitoninae likewise have connected apophyses; in Icoplax species the median areas may bear similar longitudinal ribs as in Nuttalochiton martiali, but the shells contain small intrapigmental eyes, the insertion margins have many incisions; lateral plates of the radula with rather small smooth cutting edges or without these. Like Nuttalochiton, the mopaliids as a rule possess 8 incisions of the anterior margin, corresponding to which there are often radial ribs, the sometimes connected, the covering of the perinotum may also be very similar, the cutting edge of the hooked plate is tricuspid, that of the lateral plate is smooth. Otherwise the genera apophyses are more of less large, The posteriormost shell piece sometimes has a few normal incisions, sometimes only 2 or none at all. In Katharina, and especially in Amicula, the tegmentum is reduced, the of the family are fairly variable. insertion margins is strengthened. and apophyses are greatly enlarged and the perinotum of the perinotum is In Placiphorella the anterior part considerably broadened. Such characters are special acquisitions of the individual groups. 1597 Some similarity is shown development of the series of the in cryptoplacids, which differ from the mopaliids in the smaller anterior incisions, of cases 3 Cryptoplacinae. in affinities which there are 5 Among in number of Acanthochitoninae, and in most Craspedochiton shows the genera, with Nuttalochiton, in particular the covering of the upper side of the perinotum is strikingly similar, the granules of the shell surface are enlarged, the apophyses are separate, the posterior margin is irregularly may be notched, the cutting edge of the lateral plates of the radula The tegmentum notched. Cryptochiton the large articulamentum extreme 1077 in Cryptoconchus s. s. very narrow, in is completely reduced, so that the shell consists only of is it in + hypostracum, hence a certain direction; plate, all the cutting in this genus presents an besides the large hooked addition, edges of radular plates are reduced and the nephridia The perinotum in this family has become very strong, and in the Cryptoplacinae the body has become more or less elongated, so that in some species of the genus Cryptoplax the 4 or 5 posterior shell parts have moved apart; in this genus only the anteriormost shell part has are fused together. incisions in the margin. The of the shell in Chaetopleurinae often shows great sculpture similarity with incisions is Nuttalochiton, the somewhat variable, number of perinotum sometimes consists of small scattered among which scales, posterior sometimes of needles, are larger needles or those with double cups; the lower side has smooth small of the radula has a tricuspid cutting edge, cutting edge, and anterior and and the covering of the upper side of the in on the inner side of the scales. more or less long The hooked plate Chaetopleura shaft an in s. s. a bicuspid most cases weak expansion, which in Dinoplax represents a rather large wing. Approaching the forms with ribbed scales on the perinotum are the Ischnochitoninae in which these scales are more or less enlarged and aggregated, so the needles with double cups are restricted to one this species-rich group the shell modifications; Stenochiton it the is is may be sometimes become granulose, or ribbed; in side, exceptionally the insertion notched comb-like. The cutting edge of the hooked plate tricuspid, in most cases bicuspid, the outer cusp may a small accessory cusp or entirely disappear; the wing-shaped appendage on the innerside of the shaft a small that margin. In very long and narrow; the intermediate valves sometimes have more than one incision on either margins at the and the radula have undergone some may be smooth, shell row wing is is in most cases large and often also developed on the outer side of the intermediate plate. The Chitoninae are not very different from Ischnochiton, the insertion margins being notched comb-like, which is seldom the case in the 1598 Ischnochitoninae, the marginal scales are in most cases larger, and the hooked cutting edge of the intrapigmental eyes may The end forms of plate is appear in the broadly rounded; exceptionally, shell. developmental series are represented by the this Acanthopleurinae, in which the shell contains extrapigmental eyes and the marginal scales of which are in most cases either elevated in the form of more or less long thorns or are reduced to minute needles; the radula is either similar to that in Chiton, or the hooked plate has received a quadricuspid cutting edge. Schizochiton be regarded as a special end form of is to this phyletic with large eyes which, corresponding to the incisions of the series, insertion margin, are arranged on the anteriormost shell piece in cases in 6 rows, and on the intermediate valves in 2 rows. greatly elongated and the perinotum is The perinotum is most shell is broad, posteriorly divided by a deep sinus which corresponds to a sinus last shell piece. The in the posterior margin of the covered above and below with small needle- or club-shaped calcareous bodies, and at the margin and in groups on the upper side stand larger longitudinally grooved needles. show These characters and also the complicated intestinal remarkable similarity with Cryptoplax, which probably to be explained by a similar mode of life, is coils a but in any case does not represent a sign of closer relationship. 1078 All the remaining mollusks stand in opposition to the loricates, so can be combined as Conchifera. They can be derived from that they whose nature a comparative study mainly of the most primitive gastropods and bivalves can give some information. Like the latter, their body was bilaterally symmetrical with paired nephridia and gonads as well as with 2 auricles of the heart; it is uncertain whether ancestral forms about the ventricle and the pericardium paired; at any rate may the latter arose also be assumed corresponding to the gonads and nephridia, to which If the intitial portions tract, were paired may assume of the anterior in as having been from an originally paired anlage, aorta, it was connected. which lay above the intestinal accordance with the divided heart chambers, one below the was embraced by the aortae, as a result of which the pierced heart chamber developed, frequently found in lower conchiferans. Also bilaterally symmetrical was a pair of gills (ctenidia) near the anus. The primitive shell which was overlying only the visceral that the posterior aortae arose as branches running intestine, so that the latter sack but not the head, bivalves, is to be conceived as and was posteriorly produced flat, but not bipartite as in into 2 lobes to which a pair of mantle lobes corresponds, on the lower side of which the attached. gills were 1599 As form had a soled creeping in the gastropods, the ancestral foot, the ganglia of which were rope-ladder-shaped as in the loricates; the ganglia of the head were also similar, but a ganglionic cord, the visceral commissure developed, issuing from the anterior end of the pedal cords; at all events developed it mainly innervates. it perinotum of the loricates the sides of the connection with the formation of the mantle in which lobes and ctenidia, is An equivalent of the the epipodium, which appears as a fold on body proceeding from the head backwards, provided at the margin with tentacles and on the/ lower side with sensory elevations, but it lacks the covering of the upper side with a strong cuticula and calcareous bodies. The digestive organs begin with the situated in a short snout-like process mouth opening and a buccal mass, which contains a well-developed radula with near-identical teeth, opposite to which on the dorsal wall of the oral cavity lie a pair of jaw plates; the glands of the midgut are similar to those in the loricates. From such an ancestral form the gastropods descended by an asymmetric turreting of the visceral sack covered by the The shell. asymmetry may have been the consequence of reduction of the left gonad. At any rate, the shell became spirally inrolled and gradually assumed the form of a broad, rounded cone. Because, with the enclosed visceral mass, it attained a considerable weight, it had to tip over to the left and thus came into contact with the substratum, and hence dragged during crawling, resulting in rotation until the shell acquired the most convenient position possible; this happened with the part touching the substratum had reached a position to the right beside the end of the foot. In this way one can conceive the displacement of the originally posteriorly situated parts: the shell aperture with the slit, the mantle lobe and gills, together with their centers of innervation, and the rectum along with the heart, the pericardium, dorsum, the gills are and the kidneys. The cavity gill now lies over the forwardly directed, and the visceral commissure has assumed the shape of the figure 8, the kidneys have developed in various ways. 1079 The group of marine gastropods which preserves most of primitive features in the shape of shell which has maintained living species visceral is we have make of in their organization entirely the most basal animals, thus the only rather weakly developed, the attachments of the may be coiled shell having a haliotids to commissures have become displaced somewhat the radula too the of the pleurotomariids, with a few species into the present. These of course do not correspond to the picture that epipodium itself that is especially developed. row of holes and the have indeed altered externally With loss anteriorly, their and only slightly of the operculum, the in a fashion similar to that of 1600 among Stomatia and Gena the trochids, but on the whole they have retained such a primitive organization as no other group of snails; this is well-developed epipodium and the nervous true especially of the The eyes system. The in Pleurotomaria. open cups, as are scissurellids are more and partly direction of fissurellids in the direction always small, in Incisura the shell aperture and short and have developed partly varied, is in the of trochids. They are only slightly coiled, with wide the epipodial folds are reduced, whereas a few slit; and below them small club-shaped sensory elevations are tentacles retained; the eyes are closed vesicles. of In several genera in both sexes; perhaps the d from is some trochids, a tentacle- found behind the right eye tubercle copulatory organ of neritids derived is it. Among by fissurellids, as also in of unknown function like process anterior The the fissurellids, judging from the shell, which with adjacent slit is characterized symmetry, the forms with backwardly inclined apex and bilateral its slit band show the most primitive characters. more or less broad, with smooth or central plate of the radula is finely serrate cutting edge, the large outermost intermediate plate with lateral cusp on the large pointed cutting edge; the related genera Hemitonia and Clypidina have acquired a cup-shaped shell with an an outer indistinct latter slit and the radular plates genus. Puncturella is especially in the differ distinctly, also close to Emarginula, its slit is anteriorly closed; in Fissurisepta the thus-formed hole occupies the center of the shell, so that the groups is apex is reduced. According to Odhner, the crop in these very asymmetrical, the internal villi, whereas the right half the crop of Diodora is less left is half forming a large sack with greatly reduced; strongly twisted and in on the other hand, its interior provided with dense folds, so that this genus as well as Lucapina and Fissurellidea approach the Fissurellinae; hence they can be separated as the subfamily Diodorinae. In some groups the shell is covered by a broad fold of the mantle margin. Whereas the shell in the more primitive groups completely covers the animal, it becomes smaller in the higher groups and the hole becomes larger, as Fissurellidea in annulus Odhner, where the shell represents only a fairly narrow ring, and in Macroschisma, so that these forms are to be placed fissurellids, The although patellaceans, it at the end of the phyletic development of the although without any immediate relationship to one another. is similar to Clypidina, have a cup-shaped shell, sometimes more, sometimes less sometimes approaches the anterior margin, but 1080 in deep and the apex most cases it lies in about the center. Most important for the systematic placement of the stirps is the presence of two gill rudiments together with the osphradia 1601 which lying symmetrically in the not very deep mantle cavity, a fact indicates a derivation from animals with a pair of symmetrical gills, such as only the fissurellids possess. As a consequence of the reduction of the the heart has undergone considerable modification, gills, from the middle somewhat to the left, it displaced is whereas the rectum has turned to is no longer traversed by the intestine; of become reduced and the left one has shifted One can assume that a ring of lamellae has the right, hence the ventricle the two auricles the right has anterior to the ventricle. developed on a ring-shaped blood sinus such as which projected from the fold-like On which took over the respiratory function. shell it occurs in fissurellids, of the mantle attachment and site the left side, anterior to the muscle, this sinus emptied into the auricle of the heart. In this area acmaeids a bipectinate in the has developed, probably from a larger gill lamella, and in Lottia and Scurria in addition to this a circle of gills, like in patellids is present. The efferent blood vessel of the gill of the mantle sinus and the which corresponds to the gill nerve a branch nerve of Haliotis. The anterior mantle left is a branch of the mantle nerve, is relationship of patellaceans with fissurellids is also decisively indicated by the condition of the kidneys, the left of which is very small, the right in contrast is very large. Both groups have a ring nerve in the mantle, provided, especially in patellids with tentacles; but the epipodium has disappeared. concerned; in The two groups differ as as far the pedal cords are they have retained the more original position patellids, within the musculature, whereas Sensory palps have developed in in the fissurellids they overlie it. mouth, the jaw has become the uniquely modified by the development of a cutting edge and by the attachment of cartilage and musculature on true of the very long its inner side. This is also and narrow radula, attached on the median band of which very hard, yellow-brown, detachable cutting edges appear, which occur nowhere else. The esophagus is strongly twisted, following the crop, separated from it by a constriction, stomach with the opening of the liver, is an anterior part of the then the only slightly widened main stomach and the strongly coiled intestine. In the phyletic development of the patellaceans 2 organs are especially important: the radula and the gill. The first of these in the family of patellids very clearly shows a development which begins with Scutellastra and ends with the Nacellinae; in the former there are on each side of a well-developed central plate 2 similar intermediate plates and somewhat behind bipartite this cutting edge; a plate with a large quadricuspid and uniquely the margin on simple, non-detachable cutting edges. central plate becomes narrower and either In side bears the remaining loses its cutting 3 plates Patellinae edge, in with the the 1602 Nacellinae it always rudimentary, and the adjoining intermediate is plates have also become reduced, so anterior intermediate plate and that on either side there one posterior one with is only one bipartite cutting edge; the marginal plates are also sometimes rather weakly developed. The acmaeids approach this condition. In most cases the central plate is without leaving any trace, and the intermediate plates have lost the closer together, bipartite cutting edge; more anterior one of the marginal plates, sometimes 2 (Patelloida), only one or none often come with a simple, the posterior with at all are retained. Potamacmaea and Pectinodonta have uniquely modified dentition. The radula of lepetids has the greatest similarity with Patelloida, because always 2 marginal 1081 plates are present to on either side, but one pair of plates form a single cutting edge, whereas the other pair always fused is in most cases has separate smaller, simple cutting edges, which in only one species are fused with the others to form a broad cutting edge. Just as that it rudimentary One impossible to derive the dentition of Scutellastra from is of Lottia or Acmaea, will it also seems impossible derive the to of the former from the condition existing gills in the latter. have to assume that the original ctenidia were so affected by a reduction of the mantle cavity that they lost their function, whereas respiration was taken over by the mantle, on which a ring of lamellae may have developed. The strong development of the digestive organs given the impulse to the flattening of the of the patellids are less distinct in the gill cavity. The rudiments gill acmaeids; also, a subpallial sense organ, which the patellids inherited from the rhipidoglossans, has been lost in the in the acmaeids. The auricle of the heart in Scutellastra roof of the gill heart of acmaeids has shifted considerably farther to the there can be hardly any doubt that more lies largely cavity and extends far on the right, in contrast the among left. Accordingly, docoglossans, the patellids are primitive than the in most cases smaller acmaeids and lepetids, the of which have entirely lost their gills. The trochids approach zeugobranchs with spiral shell and operculum, which the right gill and shell slit tend towards reduction, similar to the latter in condition in the scissurellids. In trochids the right it is gill has disappeared, indicated only by a blood vessel corresponding to the the right auricle; but the left gill in gill vein and the posterior part has fused with the mantle, so that the upper series of lamellae has disappeared and the lower lamellae are attached scissurellids in and most cases has first at the underside of the mantle. fissurellids the radula on 5 lateral plates in each row, not very different. The epipodium As in the either side of the central plate is which in this case are at anteriorly broadened, often asymmetrical, in the posterior part with few tentacles are similar sensory elevations as in Scissurella; the nervous system is also similar. 1603 Among the currently living genera, Margarites primitive the condition, is it more or less most strongly rounded whorls, with weak, not strikingly colored outer layer, spirally sculptured, aperture roundish without thickenings number of intermediate the plates varies reflects broadly cone-shaped with smooth or of the margin; between 4 and 6, they have well-developed, laterally cuspidate cutting edges and their shape does not distinguish them much from the lateral plates, the first of which has only occasionally lost lives mainly with sometimes in the cutting edge. Approaching this group, its which cold seas, are various phyletic series: primarily one sometimes more strongly sculptured similar, shell, represented mainly by the genera Calliotropis, Euchelus, Solariella and Seguenzia; in this series the number of intermediate plates has become increasingly reduced, so that finally only one has remained, the radula thus approaches that of the taenioglossans from which having a larger number of the in Coming Among number of intermediate the Trochinae, related to Margarites. In it differs only in close to this series are most cases cone-shaped Calliostomatinae, likewise bears a varied 1082 lateral plates. in which the radula plates. Gibbula can be regarded as most closely this series the size, shape, and sculpture are variable, the outer shell layer tends to be distinctly colored, the apertural margin not seldom has tooth-like thickenings and the umbilicus may be partly or completely covered by callus. Jaw plates are often reduced, the radula as a rule has 5 intermediate plates on either side (except in Cittarium) of a shape similar to that in Margarites, but the cutting edges are sometimes series, the shell larger. The Umboniinae may be considered of which is sometimes very similar genera with an umbilical callus; their main characteristic the as another to Gibbula, in is some the form of median radular slightly projecting plates, the cutting edges of which are not or only and lack a narrowed neck part. The Stomatiinae also seem to approach Gibbula; they are characterized by the loss of the operculum and by the progressive reduction of the spire, so that the forms have become cap- or cup-shaped. The genus Angaria resembles Liotia in the shape of the shell, but has an uncalcified operculum, and the form of the radular plates is considerably different; the genus seems to approach the Gibbula-Tegula series. terminal The anatomically little-known, generally small, from most genera of the heretofore mentioned groups non-nacreous shell, Skeneinae differ to trochids the trochids, as for instance in Fossarina; their operculum The radula by their but exceptionally this character can also be found in is uncalcified. genera shows differences, in most cases the central plate is broad, with only slightly curved cutting edge which is not demarcated neck-like and is smooth or finely cuspidate, 4 or 5 intermediate in these 1604 plates with cuspidate cutting edges. finely spirally sculptured shell, which Because of the colorless, smooth or is sometimes and probably originally group reminds of Margarites and cone-shaped, this may have them very early from the other trochids. Perhaps approaching diverged are also the cyclostrematids, previously united with them, and the radula of which has only one intermediate plate and few weak lateral plates. The turbinids differ from trochids mainly by a more or less strong calcareous deposit on the operculum; in Liotia it consists of a spiral row of pearl-like granules which do not form a solid, continuous layer; in Molleria it is only thin and spiral like the inner layer; in Leptothyra in most cases with a callous covering; in Bothropoma externally forming only a broad whorl around a median and Phasianellinae The operculum of the Turbininae in most pit. thick and externally the inner whorls are is cases not recognizable, these rapidly increase in the latter group. Liotia is thus closest to the trochids, perhaps in particular to the Gibbula group, with which the radula also agrees; Molleria and Leptothyra are related Bothropoma is distinguished by a different form of the radular plates, which however also deviates little from certain trochids and shows rather primitive characters. The more or less large species of the genera Turbo and Astraea have often lost the cutting edge on the central plate here; of the radula, the strongest plates here are not the intermediate but the inner lateral plates; both genera are closely related with one another. In contrast, Prisogaster is considerably different; the striking similarity with certain coast, such as T. two species show Tegula species from the American west gallina (Forbes) and funebralis (A. Adams), not only in the nature of the shell but also in the shape of the radular plates, so that one can think of a relationship, but the operculum externally greatly bulging, 1083 internally is calcified, somewhat concave, with nearly marginal nucleus, thus showing the same characters as in the Phasianellinae; the genus has therefore to be placed with that group, although the shell which is is internally nacreous. Of the other genera, the shell of not nacreous internally, externally in most cases quite colorful, Tricolia as well as Prisogaster have a broad central plate without cutting edge, in Phasianella is it is of the radula modified into a narrow ridge or completely reduced, and in Eulithidium the two inner intermediate plates are fused to form a secondary central plate. Because, according to their dentition, the neritaceans belong to the rhipidoglossans, and show closer relationships neither to zeugobranchs nor to the docoglossans, they can be derived only from the trochaceans, from which however they show important differences. Transitional forms between the two stirps are not nacreous shell with its known. Because of the low-spired, non- callus-covered umbilicus, the Australian 1605 Callomphala the animal Fig. 41) (cf. strongly resembles Nerita; but unfortunately unknown and hence is is it uncertain whether this similarity can be considered as an indication of relationship. The aquatic neritaceans have a bipectinate which however gill, is very peculiar in not being fused with the mantle as in trochaceans and is quite differently innervated, the nerve arising from the left nerve being a branch of the mantle gill ganglion; pleural osphradium. For these reasons the neritid homologue of the trochid explain, perhaps gill; the reduction of the latter came about through adaptation it a lacks also it distinct cannot be considered as a gill to life difficult to is on the seashore, such as Hydrocena leads, whereupon a return to the sea or to freshwater resulted in the in the nature may the new development of is more primitive and hence one neritids, however, the right auricle of the heart, which latter, has disappeared and the ventricle intestine; thus in this respect the common stem forms than the The operculum genus is at the hydrocenids are farther removed from neritids. uncalcified only in Pseudhelicina; is present in is not traversed by the is its form in this similar to the initial form: about semicircular, forming less than one whorl; in the hydrocenids and neritids a process is present internally becomes concentric. The very unique; the operculum nucleus, in helicinids the growth often strongly calcified operculum of Neritopsis is Hydrocena gill. accept the idea that the latter descended from the hydrocenids; in neritids, the a of the reproductive organs than the is absent in the cap-shaped phenacolepadids, the completely naked titiscaniids, and the proserpinines. The buccal cavity does not contain which are also lacking in some trochids, jaw plates comprised rodlets, and also no salivary glands, but only the anterior glandular pouches and a pair of esophageal sacks which correspond to the crop of the trochids, shorter in etc., and which are considerably than in hydrocenids and helicinids. neritids developed radula has 4 intermediate plates on either of which is many on the other hand Titiscania also the neritids the innermost also reaches considerable in Neritilia and Neritopsis the central inner intermediate plate, hydrocenids only a few weak plates are retained nervous system 1084 outermost very strong, especially in helicinids, the others are in most cases small, but in size; The normally side, the is in the characterized mainly by the subintestinal ganglion and the pleural ganglia plate, in have reduced and median part. in The compression of the above the anterior ends of the pedal cords, in helicinids are probably also hydrocenids by interruption of the supraintestinal part of the visceral commissure. The left position of the kidney, which undoubtedly corresponds to the one of the trochids, somewhat varies according to the extent of the 1606 mantle cavity, and similarly its shape and the urinary chamber; instead of the club-shaped papillae of the trochids, here more or less strong folds are developed, a nephridial gland is absent. A right kidney is not present; may be the blind sack on the gonoduct of Hydrocena remnant of such this kidney, may also be retained but no longer has an excretory function. In considered a in other neritaceans, neritids the oviduct has The nature of the ? genital simple opening, is the most primitive in the retained a connection with the pericardium. of Hydrocena, with tract stirps; its the helicinids differ from this in the development of a separate opening of the bursa copulatrix into the mantle cavity and in neritids the is considerably enlarged as a result of spermatophore formation, its bursa opening has therefore moved farther forward, and finally in some groups a 3rd opening is also developed. In contrast, the gonoducts of Titiscania Whereas the are simple; the receptacula seminis are a unique structure. hydrocenids and helicinids lack a d copulatory organ, the neritids in most cases have a lobe-shaped process posterior to the right tentacle; Phenacolepas As it is in finger-shaped. whole, the neritaceans are a highly developed stirps of a rhipidoglossans, which are unique in various organs so that they are not in phyletic direct relationship with taenioglossans, even though the reduction of the right kidney does indicate a certain relationship; moreover, the structure of the gonoducts of Hydrocena is essentially like those of several taenioglossans. Considerably more divergent are the cocculinaceans, a group of small, mostly deep-sea, snails with cap- or cup-shaped shell, of cocculinids still uniquely modified in lepetellids. A ctenidium absent, and is cases replaced either by a larger folded lamella or leaflets which the have a distinctly rhipidoglossate dentition, whereas is in by few or it is most several which, similar to the condition in patellids, are attached on the underside of the mantle, but only on the the simple sack-shaped kidney, right. The short pedal ganglia, and the hermaphroditic gonad with simple gonoduct represent characters of a unique development. The architaenioglossans are interrelated shaped pedal ganglia and their more or showing a to have primitive organization, certain resemblance to the trochaceans, arisen. distinctly differ still only by the rope-ladder- less Among from which they seem these the cyclophorids are land snails, from the remaining families living unclear from which marine snails considerable similarity of the dentition of with that of Lacuna may indicate among this (cf. Fig. relationship, and the It is although the some cyclophorids because the shell form does not contradict be regarded as the most primitive they derive, a certain which in freshwater. latter 84) especially group can the marine taenioglossans. As 1607 in the trochaceans, the pleural ganglia ends of the pedal cords, but move away from them, weak the rather of cyclophorids some genera in lie at the anterior (Poteria, Cyclosurus) they so that they are connected by distinct connectives; ganglia are removed from the pleural ganglia, parietal the supraintestinal ganglion farther away than The jaw the subintestinal. and the salivary glands are well developed, the buccal pouches are plates small; the kidney has no separate urinary chamber. The oviduct leads the widely open glandular duct, attached at the posterior end of into which is a sack-shaped receptaculum seminis, a bursa copulatrix being absent; the duct cf similarly shaped, is it! has a spermatophore gland at the posterior end of the wide terminal part; attached behind the right tentacle is the penis, connected with the genital opening through a groove and innervated from the Accordingly, it shares still the —probably from to right pleural may be assumed ganglion. that a An epipodium is absent. group of marine gastropods, which ladder-shaped pedal ganglia with the trochids the group of the Margaritinae, in which the radula tends number of the intermediate plates (cf. Fig. 31) approaching the littorinaceans in the structure of kidneys and a reduction in the —but was reproductive organs, migrated to the seashore and then to land, lost the and gave gill, groups shell, rise to the cyclophorids. among themselves can be The interrelationships of the assessed only from the character of the the operculum, and the radula, because the comparative of the animals has in anatomy most cases not yet been investigated. Probably the broadly cone-shaped, medium-sized shells with tightly coiled horny operculum are to be regarded as primitive, similar to Leptopoma, possibly also Craspedopoma, on the other hand a calcified operculum and turreted different shell or the fatty shine of the surface of Pupineae or the radular forms (cf. Figs. 81 and 85) indicate secondary modifications; the European group Cochlostoma on the whole seems to be the most different. The nervous system of the by the viviparids differs from that of cyclophorids moved away from the pedal ganglia and toward the cerebral, as well as by the retention of a lower esophageal commissure. The neck lobes are similar to those of trochids; they receive their nerves from the pleuropedal connectives, the margin of the right pleural ganglia having one also receives a branch of the mantle nerve, in the trochids they are supplied from the anterior part of the pedal cords; perhaps these nerves, along with the pleural ganglia, have become displaced farther forward in The gill is retained here, its leaflets The form of the radular plates shows little the viviparids. are attached to the mantle. similarity with that of cyclophorids. A blood gland, which special acquisition of viviparids is the long ureter; the is otherwise part of the nephridial gland, in this case 1608 wall of the auricle. lies in the Use of the right cephalic tentacle as c copulatory organ as well as viviparity are also peculiarities of the family. thus to be assumed that It is it trochids but in other organs it has retained some primitive characters of has developed so independently that a close relationship with cyclophorids genus distributed The widely most primitive, whereas the out of the question. is may be Viviparus the North American Campelominae because of their small radula with simplified plates, the large foot, and the weak neck lobes are the most divergent. The ampullariids may have derived from viviparids, for the two agree similar forms as the in their habitat in freshwater, similar shell, operculum, as well as in the neck lobes, but in other organs they have undergone a unique development. Especially striking is the division of 1086 the mantle cavity, the right part of which contains the serves as left a lung. In the whereas the gill, nervous system the lower esophageal commissure and the fusion of the pleural ganglia with the anterior parts of the pedal cords is a primitive character, but the union of the subintestinal ganglion with the right pleural ganglion The condition of organ at the mantle margin are also unique. African Afropomus not known. As may be the Among especially primitive, higher and divergent characters shaped (Ceratodes) or (Pila), a peculiarity. is 1 the kidney and the development of a copulatory d the genera, the however may qualify: sinistral (Lanistes) shell, the calcified reduction of neck lobes (Asolene), West anatomy its is the disk- operculum and the bipectinate osphradium. There are divergent opinions of the systematic position of the which inhabit Lake Tanganyika; in most cases they are lavigeriids, included in the melaniids, but, according to Moore, the nervous system is considerably different from that of melaniids and resembles that of viviparids, with the rope-ladder-shaped pedal ganglia, a lower esophageal commissure, and the pleural ganglia lying close to the cerebral ganglia. The outer lateral plate of the radula is similar to that in melaniids, less so the other plates, but this can be viewed as an analogy, and perhaps Lavigeria can be seen as a form, sculptured similar to Paramelania, derived from a Viviparus-tike gastropod. Among traits the marine taenioglossans, the littorinaceans of primitive organization. The medium high shell is not nacreous, in show some most cases more seldom flat or turreted above, aperture roundish, operculum uncalcified, in most cases with few whorls. The with pleural spire, ganglia adjoin the cerebral ganglia, the pedal ganglia are not rope-ladder-shaped but roundish and each with 2 small ganglia attached to it, the posterior pair of which in Lacuna is connected by a commissure. — 1609 This posterior pedal commissure seems to be of special interest, because is it found also some other groups and is thus important The ganglia of the rather long in recognition of their relationships. for the visceral commissure are only indirectly connected with the anterior mantle nerves. Because some littorinids live on the seashore, their gill, which in Lacuna together with the osphradium and the hypobranchial gland are well developed, tends toward reduction; Cremnoconchus has climbed into the mountains. The radula of lacunids is moderately long, whereas in littorinids it often attains an enormous length. The intermediate plate always has a sinus on the outer margin; the cutting edges in most cases have several cusps. The salivary glands each have a very narrow efferent duct; on the esophagus on either side lies a somewhat folded buccal pouch anterior to the cerebral ganglia, its posterior part is narrow. Lacuna has a well-developed may anterior pedal gland with a blind sack; also be of significance that in the left mantle margin lie a of subepithelial glands, which open on the underside. is It it number uncertain whether the tentacle-shaped processes of the opercular lobes of Lacuna may be lacking. considered as remnants of the epipodium; anterior lobes are The oviduct of Littorina — that of Lacuna has not been studied end lies a receptaculum seminis albumen gland, which forms the posterior part of the "uterus" and which is joined by a capsule gland and in most cases a jelly is connected with the pericardium embedded at its in the gland; the blind-sack-shaped bursa copulatrix also opens at the opening of the uterus. 1087 In d the penis the sometimes by an open prostate, has ciliated is connected with the sperm duct groove, the glands of which serve as sometimes through a closed canal; cement glands. Among penis in Littorina species the and Haloconcha may be primitive forms, Cremnoconchus and Tectarius the most modified. The pomatiasids shows striking similarity in the nervous system to special the littorinids, Laevilittorina littorinaceans; moreover, like Lacuna, they have in addition to the main commissure of the pedal ganglia, also a weaker posterior one, but the small accessory ganglia are not separated. Because they are land dwellers, they lack a operculum gill, is shape of the shell median furrow However, the but a bulge-shaped varied, is in other is rarely thin also osphradium is retained. and horny, more often varied. The division Their calcified; the of the foot-sole by a only a reinforcement of the condition in Littorina. organs there are considerable differences, such as in form of the radulars plates, the outermost of which is greatly broadened, the esophagus having a ventral conducting groove with basophilic glandular cells, whereas the remaining part has an epithelium similar to the crop of rhipidoglossans; the kidney has no nephridial 1610 gland, the uterus largely groove-shaped, the penis is attached farther is back on the right side and to the ganglion. Hence, The center of the littorinaceans. among Indo-African region; innervated from the subintestinal is hardly possible to directly relate pomatiasids with is it development probably their the Pomatiasinae, Leonia lies may be in the the most divergent form, whereas in the series of the Chondropomatinae unique forms of sculptures have developed, among which Blaesospira needs to be mentioned The (cf. Fig. 110). relationship of planaxids which, according to Bouvier, is also unclear, the nervous system of very similar to that of Littorina, which especially of the pedal ganglia; the subintestinal ganglion has true moved toward The shorter. spiral is is the shell left pleural ganglion aperture and the cerebral commissure strikingly different, is as is also the scarcely operculum and especially the radula, the central plate of which bears a couple of basal cusps similar to the condition in Batillariinae, the lamella on the outer lateral plate only analogous with has some similarity with Pomatias, but The hydrobiids can be probably the littorinaceans with greater related to Their nervous system certainty. is it. is more concentrated because of a shortening of the connectives, and the parietal ganglia may touch the commissure often connects a pair of pleural ganglia; a posterior pedal accessory ganglia. With few exceptions, the animals are small, with a more or less operculum is high shell and in most cases roundish aperture; the originally horny and plate sometimes very long a spiral, with few whorls. The central two or more basal cusps, the intermediate plate of the radula has as a rule lateral process and almost always a cuspidate cutting edge, the lateral plates in most cases finely serrate cutting edges. A majority of the hydrobiids live in freshwater, but they belong to the large stirps of the Rissoacea, of which marine. Anatomically they are classification many groups are poorly studied, so that their based on the condition of the shell, operculum, and may be that marine rissoids are and hydrobiids. Among them, the groups intermediate between lacunids some of which may be radula; 1088 is still it are primitive, the shell of at the widely distributed, which is united in the genus Cingula, considered as most not or weakly sculptured and has no sinus end of the columellar margin. Like Rissoina, which according to is not different from Rissoa, the Barleeinae and Hemistomiinae the radula have an internal process on the operculum, whereas their radula has a more or less divergent form. Of the hydrobiids, to Hydrobia; their penis is simple, attaching in the on the right, some genera are close neck region somewhat the operculum spiral, thin, with few whorls. The largest forms have developed in Lake Baikal. The penis has sometimes attained 1611 a lateral process or broadened leaf-shaped. Truncatella species inhabit is the seashore and Geomelania the dry land. Because of the tightly coiled operculum and the shape of the radular Hydrococcus Australian genus main character of the Bithyniinae. The micromelaniids, likewise the is the plates, the Stenothyrinae; the calcified operculum is transitional to living in freshwater, have a somewhat more concentrated nervous system with simple pedal ganglia and a radula similar to hydrobiids, but without the basal cusps of the central plate. Because the genus Emmericia also has such a dentition, are can be placed it in the latter family; the shell Another family of the Rissoacea are the assimineids, which live on the seashore, in part on of the radula are originally The land. plate lateral become As retained. A in the latter, the gill is reduced, commissure posterior pedal are fused with the pleural ganglia. As lost, and the considerably broadened, is with very numerous fine serrations, which makes pomatiasids. in part basal cusps on the central plate but often distinct moderately broad outer initially is shapes different. it similar to that of whereas the osphradium present, the parietal ganglia is in the related groups, the salivary glands are simply tube-shaped, the esophagus has a posterior blind-sack- shaped gland, homologous with the crop. The closed sperm duct has a strong prostate; the large penis, attached on the neck, receives a nerve from the right pleuropedal connective; before opening into the glandular uterus, the oviduct is connected with a sack-shaped receptaculum seminis. There seems no doubt that in this family the littoral species of the genus Assiminea are the most primitive, the land-dwelling Omphalotropidinae are primitive. less pomatiasids, The which were latter, earlier do not seem to be closely related similarities; their foot-sole is undivided, their in united with spite nervous system considerably more concentrated, and the esophagus is different. Bouvier believes that the hydrobiids are so closely related terrestrial latter acmids that they are certain anatomically may be still the of certain to considered as aquatic acmids; but the poorly known, their radula may betray a resemblance to that of assimineids, to which they are perhaps closest. According to the condition the shell of which in case rissoids. A is striking peculiarity and extensible as of the radula, the family of the adeorbids, low-spired, also come shown by gill, is in trochids, but, in system a close relationship of the an extent that the close to the marine which is bipectinate view of the concentrated nervous latter can hardly be assumed to such an inheritance from the trochids; it has probably be considered a special acquisition as a consequence of the burrowing mode of life. In other organs too the adeorbids resemble the rissoids, but to this gill is 1612 1089 a<J copulatory organ is stated to be absent; on the right mantle margin of Adeorbis 2 finger-shaped processes are located. Because in some genera the animals are unknown, their interrelationships remain uncertain, same the is true of the affiliation of the fluviatile genus Phaneta to this family. very remarkable that a similar bipectinate and extensible It is gill is also present in the valvatids, which also have a finger-shaped process on the right mantle margin; their radula differs mainly by the absence of basal is similar. The kidney cusps on the central plate and their nervous system has attained a ureter opening at the mantle margin, and the reproductive organs have assumed a special peculiarity, wherein the two sexes are combined under retention of those parts present in related families, such as a receptaculum seminis on the 9 and on the part, c? part a prostate and a penis attached below the right tentacle. The viviparous group Borysthenia is an offshoot from Valvata. A phyletic series, which probably arise from rissoid-like forms, includes mainly the Cerithiacea, to which the ptenoglossans are probably allied. Their shell is in most cases turreted, the aperture originally roundish or ovate and without lower canal, although this feature and sometimes a short siphonal process has developed 1 system A most cases characterized by the approach of the pleural in is some groups. in copulatory organ. The nervous special character is the absence of a d ganglia to the cerebral ganglia and of the subintestinal ganglion to the left pleural ganglion ganglion, whereas the supraintestinal distantly located; the pedal of ptenoglossans commissure is is rather simple; but the nervous system very different. The radula shows some similarity with is sometimes the central plate also shows indications of basal denticules, but these are in most cases lacking; its cutting edge has next to the median main cusp, on either side an accessory cusp, or 2 or that of rissoids, 3, rarely more, as in turritellids; the intermediate plate is variably broad, often with a shorter or longer lateral process and with denticulate cutting edge, the lateral plates are varied, sometimes pointed, sometimes with broadened cutting edges, which often bear a few identical cusps. The plates of cerithiopsids are dentition 2 cusps. is more irregular, in The ptenoglossans have assumed snails, the buccal mass of which special glands larger is and often by unique abnormal formation of the radula solariids, Triphora the taenioglossate replaced by numerous identical, very small plates with 3 or which stylets. may like the mathildids number of the dentition of predatory characterized Among by large plates, occur (Turritellopsis), and in the probably approach the radular plates has jaw the turritellids also an turritellids, a developed, which show some similarity with those of ptenoglossans. In this series of snails, the non- 1613 being more or less long, some forms have retractible snout otherwise attained a long retractible proboscis in adaptation to a predatory of life; the esophagus shows differences correspond The osphradium, which in is .ig mode to the nutrition. most cases cord-shaped, can become bipectinate. group of prosobranchs various developmental series probably In this initial forms still showed no Most remained in the sea. Of these, the whose organization is little known, and the Litiopinae separated early, in which in most cases the or only a 1090 weak small Finellidae, seem to apertural sinus. be primitive forms. It is doubtful whether the arising cirri on the The foot of Litiopa can be considered as the remnants of an epipodium. of Diala has resemblance with some shell rissoids, the operculum and the radula are also not very different. Standing close to them are probably and various Cerithium groups. Plesiotrochus and may also have come from litiopines. It is uncertain whether the large Companile is related here the form of the shell and of the aperture appear to indicate this. The potamidids, in most cases Bittium first Trochocerithium — of the operculum, represent living in brackish water, with several whorls another series, which probably branched very early; Batillariella and Pirenella have weakly indented apertural margins, whereas other in genera a distinct sinus and a columellar process have developed, apparently independent of the cerithiids. melaniids, A similar condition exists in the freshwater which however have more often retained the non-indented aperture, although here again forms with distinct sinus have developed in some groups. Less closely related with these groups are the always live in the sea and, with the exception turritellids, aperture and an operculum consisting of several shell Connecting to similar forms, besides the in which of Profoma, have roundish narrow whorls. most cases likewise turreted mathildids, are the low-spired to disk-shaped solariids as well as the in most cases very spiral vermetids, shell, irregularly formed but sometimes among which Tenagodus is initially still distinctly characterized by the slitted and perhaps also the very small caecids. The ptenoglossans, which probably stand have posed considerable close to the cerithiaceans, difficulties for the systematists. Originally on the radula alone, the group included families which not have based to be excluded, so that only the scalids and the janthinids belong here. That these two agreement are closely related in the condition is beyond doubt because of the wide of the highly peculiar buccal mass of Scala and Recluzia. They have however assumed a divergent mode of whereas the scalids crawl on the ground produce a foam raft like most life; snails, the janthinids with their pedal glands by which they swim on the 1614 ocean surface, where they feed mainly on the relatively large Velella and Porpita; hence their proboscis has become wider and shortened, which necessarily resulted in a widening of the ganglionic esophageal ring. In case from a "brevicommissurate" nervous system a "longi- this commissurate" has developed. The zygoneury dissimilar; may be it The scalids. lateral which structure, is that a left folds zygoneury in the two families is also not always developed in is on the foot of Janthina are probably a new not homologous with an epipodium. statocysts tend to reduction. Both families agree The eyes and of in the possessions mantle glands which produce a purple-like secretion and both have protandrous hermaphroditic gonads without penis, within which characteristic motile "spermatozeugmata" are developed through which fertilization The takes place. of scalids shell is in most cases turreted, the aperture roundish without distinct spout, the operculum spiral with few whorls; among them the genus Acirsa may be the most primitive. Recluzia stands closer to scalids then Janthina; the 1091 The genus latter is peculiar in the color and shape of the shell, the clefted tentacles, the large buccal mass, and the condition of the nervous system. Aside from the radula, the anatomy of cerithiopsids According & Forbes Hanley is still unknown. of the animal of Cerithiopsis tubercularis by a figure to (Fig. 896b), is has no projecting snout, the eyes lie on the dorsal side of the head at the base of the finger-shaped tentacles, the foot anteriorly strongly produced, clefted at the margin, is opening of a gland penis in the middle of the sole. It is not and has the known whether a Thus is view of the considerable differences from seems probable that, in spite of similar shell shape (cf. present. is cerithiids, Bittium, it Fig. 896a), Cerithiopsis not closely related with them, is whereas the animal of Triphora (according to Chiaje) appears to be similar to that of Bittium. Judging from the figures of melanellids, their head and foot retractile labial is rather similar to that of Cerithiopsis, they have a long proboscis with rudimentary buccal mass, a well developed and sole gland in the foot, a bipectinate osphradium, and separate with a penis behind the right tentacle (Fig. 896c). Hence, a two groups seems possible. Coming close to the melanellids are the stiliferids, which are more or less adapted to a sexes relationship between the mode of parasitic life. The very small aclidids are also probably closely related to melanellids, but whether the pyramidellids are also related to them, seems somewhat uncertain on the basis of our present knowledge of anatomy, but their retractile it esophageal ring, but there lack a is indeed possible. They also have a long proboscis without a radula, gill just like the is it is closely surrounded by the a hermaphroditic gonad; the small species aclidids. According to the shell and the 1615 operculum, among the melanellids, Niso has strong similarity with certain may be most pyramidellids and closely related to them. is It uncertain to which taenioglossans the entire group belongs; according to the shell and the operculum one could think of the Rissoacea. Fig. 896. (Montagu); a, c, Bittium reticulatum (Da Costa); b, Cerithiopsis tuberculahs Eulima (= Melanella) alba (Da Costa). Head and & Forbes Another series of taenioglossate foot, after Hanley. snails, which may have arisen from the primitive groups of Lacunidae-Rissoacea, begins with the Fossaridae, the anatomy of which unfortunately is still scarcely known, except for the radula. Based on the shell form, the genus them can be considered like that of Couthouyia as the (Fig. most primitive 247), is Megalomphalus among (cf. Fig. 246), its radula, similar to that of rissoids and adeorbids; the operculum has a nearly or completely terminal nucleus. According 1092 to the shell Fossaridae. and the radula, the Vanikoridae stand close Their typical propodium and on species, either side a V. cancelata, wing-shaped lamella on the head forms a rather short snout and the eyes lie in to the has a leaf-shaped foot; the the posterior part of the tentacles, the penis attaches behind the right tentacle. It is not known whether the fossarids have an equivalent of the anterior pedal lobe, but such a lobe is also present in related families, because the "lower lip" of trichotropids and capulids is innervated by the pedal ganglia and corresponds to the propodium of vanikorids and amaltheids. The trichotropids still have a spiral shell and capulids a cap- or cup-shaped plates of the radula are in and an operculum, the amaltheids shell without operculum. The lateral most cases simply pointed; the esophagus is narrow; the animals are often protandrous hermaphroditic. The pleural 1616 ganglia and both are connected with the ganglia adjoin the cerebral subintestinal ganglion, the right alone with the supraintestinal ganglion. The osphradium capulids it is in amaltheids thread-shaped, in trichotropids and is bipectinate. calyptraeids also belong in this group of snails; the The propodium median parts is fused with the under side of the head, so that it has of two lamellae, which anteriorly terminate below the tentacles; form the there is no doubt that these lamellae are not homologous with an epipodium but with the propodium of the related genera. The nervous in its system is highly concentrated, the paiietal ganglia lying close to the pleural ganglia forms side, and connected is still distinctly spiral it later to both,'. The shell with central apex and in the flat more original or concave under- assumes a cup-like form with funnel-shaped basal lamella, or the apex approaches the margin, giving rise to the slipper-shape; the more or less large salivary glands are sack-shaped and do not traverse the ganglion ring; the of the radula are cuspidate or smooth; the lateral plates esophagus has no glands. The gill consists of long filaments, the osphradium is short and bipectinate. The xenophorids have a {Trochatella) (cf. lower side from the upper but which here is shell very similar to that of Calyptraea 256), with the free shell margin separating the Fig. side. Like the latter, they have a propodium not fused with the head, and like them they have a gill consisting of long filaments; the radula with simply pointed lateral plates is also similar, likewise the sack-shaped salivary glands and the long thin esophagus; the similarily shaped penis, situated on the right side, has a groove. Contrasting these similarities, there are nevertheless ciliated some differences: the retention of the operculum, the loss of the creeping sole, the long thread-shaped osphradium, the long connectives between the pleural and parietal ganglia corresponding to the lengthened neck region. However, it is to be assumed between that a relationship exists calyptraeids and xenophorids in that both groups have originated from common ancestors which still had an operculum, a creeping sole, a simple osphradium, and distinct connectives between pleural and parietal ganglia, so that as a whole they had greater similarity with xenophorids. Because, according to the form of the foot and the other characters of the animals, they belong to the strombaceans, this stirps cannot be placed in relationship with the Cerithiacea but with the Calyptraeacea. The shell which still have form of the Strombacea is varied; that of struthiolariids, a normal creeping foot with poorly developed propodium, has similarity 1093 with trichotropids (cf. Figs. 251 and 260). In other genera the spire is erevated turret-like and the aperture has acquired an elongated channel, in Strombus and Pterocera and apertural margin is often widened and is 1617 sometimes produced into processes. The The heteropods life, ciliated groove, which in the <S 9 ends at the propodium. leads to the penis, in the which have shifted also, swimming mode of to a are very probably related to these groups provided with a propodium; based on the shell one could think of a relationship between Protatlanta and Lippistes. The pterotracheids, which have completely represent the most highly developed forms In contrast to this series in lost the shell, among them. which the esophagus is narrow and more or less long, the naticids have a strongly developed esophageal gland, which corresponds to the crop of the primitive prosobranchs. They also have a kind of propodium, but Strombacea, it basically different is from that of on the anterior part of the foot a shield-like thickening etc.; has developed, which is laterally separated from the lower part by a groove and posteriorly has a free margin which overlies the head. This unique structure is correlated with the plough the sand in order to drill into mode of of the naticids, which life bivalves and snails present in suck out their contents. The drilling it and mouth opening, the tall epithelium of which produces an acidic secretion. The pleural ganglia adjoin the cerebral ganglia, the commissure of which is to sometimes rather long, whereas the them by by a gland effected parietal ganglia are at the connected with distinct connectives, the subintestinal ganglion only with the left ganglion, the supraintestinal pleural is ganglion not only with the right pleural ganglion but through the mantle nerve also with the left one. osphradium is bipectinate. may be Frovina similarity with In the naticid the most primitive; its the small series, shell The Antarctic and operculum have Lacuna, and also according to the radula one can think of a relationship with the lacunids and rissoids; still it has a bipectinate osphradium and probably an indication of the propodium. In the more become enormously highly developed naticids, the foot has gradually enlarged; the operculum is sometimes distinctly calcified and the radular plates can lose their accessory cusps. Occasionally the eyes are reduced. The forms; lamellariids and cypraeids are to be derived from similar both of them have lost the operculum, their mantle strongly developed and can partially spiral is only weak, with a with few, rapidly increasing whorls, or cap-like. The radula has variously formed plates, the lateral plates are in most cases rather short and pointed; in Lamellaria they have disappeared. nervous system parietal is more or less concentrated, in combined in The Lamellaria the two ganglia are connected with the two pleural connectives. often or completely enclose the shell; they lack a propodium. The shell of lamellariids wide aperture, initial is Whereas the Lamellariinae have separate the Marseniniae and Velutininae. ganglia by short sexes, they are 1618 Among cypraeids, the especially the relationship with lamellariids. The only Triviinae betray a slightly coiled shell is, close however, low spire and narrow, terminally groove-shaped and the mantle anteriorly has an elongated siphonal canal, whereas in lamellariids it forms only a fold. In addition to the usual shell differently formed, with aperture, 1094 muscle, there is osphradium bipectinate. sole. is also a smaller A one lying anteriorly and to the narrow tube-shaped gland opens The buccal mass contains jaw plates left. The in the foot- and a radula with short pointed esophagus has a strong gland. The bipartite kidney and the ? organs with a few seminal vesicles are also similar. According to lateral plates; the Pelseneer, Trivia has an uncalcified larval shell which, as in Lamellaria, is enrolled in one plane and surrounds the shaped calcareous initial whorls of the Helix- shell. The remaining cypraeids have developed more or whereas in Trivia the osphradium the mantle cavity and the gill cavity has deepened, so that lies rather far less divergently; forward transversely in forms a moderately deep arch, the mantle extends almost to the posterior end, the forming a deep arch and the osphradium having become triradiate. In the nervous system, the pleural ganglia adjoin the cerebral ganglia and it gill the supraintestinal ganglion is sometimes closer to the left, sometimes to the right pleural ganglion, connected to both, whereas the subintestinal ganglion is more or less removed and is sometimes directly connected with both pleural ganglia, sometimes only with the striking character of the nervous left. The most system of higher cypraeids is the presence of rope-ladder-shaped prolongations of the pedal ganglia, which however do not contain a continuous cortex of ganglion contain any cells in the posterior parts; Trivia there are only simple nerves cells and do not corresponding with them in which are not interconnected. These cords of the cypraeids have been considered as indication of primitive and this group has been placed with the architaeniohowever have no closer relationship with the latter and because as a whole the triviids are the most primitive cypraeids, one will have to assume that their posterior main nerves in the foot have organization, glossans; they secondarily connections. become It is partly ganglionic and have retained some transverse incorrect that the heart and 2 auricles; Pelseneer one assumed auricle is "... The radula has undergone modification Pediculariinae it is still most similar intermediate plate of Jenneriinae show is according to une ecbolie anormale du ventricule." in the subfamilies; to the Triviinae, the division striking, transitions to the Amphiperasinae, in whereas the which the outer lateral in the of the plates lateral plate greatly broadened and is comb-shaped serrate; the radular plates of Cypraeinae have assumed greatly divergent forms, whereas the jaw plates have disappeared. is 1619 appears uncertain, to which taenioglossan group the Doliacea are It Bouvier considered related. probable that they have developed from it chenopodids (=aporrhaids) through the extinct columbellinids; intermediate forms the osphradium in these may have become modified from the thread-shaped to the short bipectinate one. According to the shell one can which also think of the struthiolariids, the foot of does not posses still a distinct propodium. Aside from the modification of the osphradium, one must assume is the result that the development of the long pleurembolic proboscis of a transition to way of a predatory life and a better development of the salivary glands and the esophageal gland. The nervous systems of aporrhaids and doliaceans are zygoneurous, both ganglia being removed from the pleural parietal doliaceans, the genus Oocorys noted by may ganglia. Among the whole be the most primitive; as on the one hand bears similarity with Fischer, the shell P. as a Liomesus and Buccinum, and on the other hand with Cassidaria, Dolium and Linatella, and the operculum would be Cassidaria, 1095 to is Most spiral. closely related to it which the other cassidids and cymatiids connect, then the bursids, doliids and finally the pirulids, the nervous system of which is most concentrated and according to Bouvier is similar to that of vasids and volutids. One can interpret the mentioned resemblance of the shell of Oocorys with buccinids and also with some other stenoglossans as a sign of with Lathyrus for instance relationship, (cf. 275) Fig. etc. because it cannot be doubted that stenoglossans have developed from taenioglossans and in that the among the latter and Doliacea are closest to them. following characters: shell osphradium bipectinate, proboscis They agree and mantle with siphonal process, retractile, buccal mass small, esophagus with gland (rarely reduced) the efferent ducts of the salivary glands do not traverse the ganglion ring, nervous system zygoneurous, statocysts with one statolith, a penis present. The original form of the stenoglossan radula, which occurs in families, consists of a central plate with 3 cusps at the posterior . and on either side a simply pointed lateral plate (cf. Figs. some margin 309, 381, 385, 393, 407, 409 and 411). The concentration of Lathyrus cerebral The it is the ganglion mass somewhat is varied, in similar to Pirula; the buccal ganglia have approached the ganglia. families belonging to the stenoglossans are interrelated. The toxoglossans have muricids, also the shells may be more or less closely a nervous system similar to certain rather similar Turrinae with simply pointed lateral plates is and the radula of some comparable with that of muricids; thus one can assume that the toxoglossans stand closely to the 1620 muricids, and here teeth without basal first the Turrinae, and then the groups with arrow membrane, and the cases lost their radula. which have terebrids The magilids without radula have in most also originated from muricids. The radula of the buccinaceans as a rule has one inner or more cusps on the lateral plates and these plates may be sometimes 376 and 377); there are occasionally greatly broadened (cf. Figs. 365, small tubercles or folds on the columella. developed, as also in olivids, by a groove, corresponding delimited lateral parts of the foot may The foot is often strongly of which Pseudoliva has an anterior margin to the propodium of Oliva; the be greatly broadened and can be used for most cases the animals plough through sand similar to naticids. The shell form of the olivids is sometimes similar to that of certain buccinids, the radula of Pseudoliva also shows similar characters swimming, but in 343 and 383), but in most cases the lateral plates have only one cusp. The nervous system of Oliva is highly concentrated. On the whole the olivids may be most closely related to muricids because of the shape (cf. Figs. of the radular plates, the presence of an accessory pharyngeal gland and an anal gland. The shells of the mitrids, vasids, volutids, cancellariids and most cases shows marginellids in distinct columellar folds. The radula in forms can be very similar to that in muricids; an more gland is present only in some groups, whereas it is pharyngeal accessory the vasids, the genus Metzgeria may be the others. Among lacking in primitive most primitive, but its relationship with Vasum seems uncertain. The lateral plates of the radula are reduced in Cylindromitra, Harpa, most of the volutids, the genus Cancellaria and marginellids; the entire radula is lacking in the genera Scaphella and Admete. undergone 1096 distinct modifications in some The nervous system has families: Bouvier thought that volutids and turbinellids (= fasciolariids) stand at the beginning of developmental series, which connect two to the taenioglossans, because their nervous system with the supraintestinal ganglion rather distantly removed from the pleural ganglia, is still less concentrated than in other stenoglossans; but this view seems too one-sided, because the modifications within the families have not been taken into consideration; thus the supraintestinal ganglion of Murex trunculus is considerably farther removed from the right pleural ganglion than in some other muricids; on the other hand in Melo indicus (Gmelin) = Cymbium melo (Solander) according to Fleure, it lies directly at the right pleural ganglion, whereas Bouvier found a long connective between the two in Cymbium (Cymba) neptuni (Gmelin). Cancellaria approaches volutids, the connective of the supraintestinal glands is ganglion being long; a pair of accessory pharyngeal present and the radula because of the low is very unique. The shell of marginellids, spire, the inflected apertural margin, and the mantle 1621 covering is some has attained it, similarity with cypraeids, which however not an indication of relationship. Concerning the between interrelations prosobranchs and opisthobranchs, agreement has been recently reached to the extent that the actaeonids are on the whole closest to prosobranchs and are to be considered as transitional forms to the shell-bearing opisthobranchs from which then the shell-less forms have developed. However, at the same time the question as to which prosobranchs are closest to the actaeonids is still in dispute. Mdrch and other malacologists have placed the pyramidellids with the tectibranchs, in contrast Pelseneer has claimed that these two groups are not related with one another. After an examination of Odostomia species he says that these are hermaphroditic, is the only character in which they agree with actaeonids, but that this for in contrast to the latter, the cerebral the esophageal ring does not lie and pedal commissures are short, anterior to the salivary glands, and the statocysts contain a statolith. Hence, according to him, the tectibranchs are closest to trochaceans. This argument The degree of untenable. the commissures alone is completely insufficient and relationship cannot be based on the length of the ptenoglossans). It can be stated with between pyramidellids and actaeonids. part so similar that one could be in doubt as to which (cf. certainty that a relationship exists The shells are in of the two groups they belong; thus certain Leucotina species are hardly separable from Actaeon by the shape and sculpture of the shell, and it seems possible that this group, the anatomy of which is still unknown, is intermediate between the two families (Fig. 897). The operculum is also very similar. In one Pyramidella species from Papeete, the ganglion ring embraces the anterior part of the invaginated proboscis, which widens considerably posteriorly and here instead of the radula contains numerous small thorns. In the mantle cavity are found 2 opposing folds each of which bearing a band of tall ciliated epithelium, quite like that in Actaeon; to the right of the dorsal fold 1097 bears a median fold. lie few gill lamellae. The dorsum The pedal ganglia have 2 commissures. The closed hermaphroditic duct opens on the right side of the head in a fold, which perhaps corresponds to the penis of Actaeon; opening nearby is a blind sack, which lies above the cerebral ganglia and may be a seminal The ear-shaped cephalic appendages fo pyramidellids may have vesicle. modified into the lobes on the head of Actaeon; the position of the eyes in the head and the histology of the nervous system also agree. Both families have assumed a different mode of life and undergone modifications as a result; so far as they have been examined more closely, one cannot consider one of them as precursor of the other, but derive both of them from common ancesters, which certainly had no closer relationship with trochaceans. 1622 :^, %r'-b2'i£\ s 1096 Fig. 897. a, Leucotina gigantea (Dunker); b, Actaeon The tornatilis (Linne). species included in Leucotina are variably high-spired, the typical species niphonensis not L. Whereas the turreted, in shell much taller of pyramidellids cephalaspideans there is is than Actaeon. in most cases more or less an increasing tendency toward shortening of the spire and elongation of the aperture, so that the opening of the mantle cavity widens and the posterior. It is crossing of the visceral commissure, primitive groups, due to the right and the to shifts is still clearly noticeable annulled. This condition of the gill is some possible of which has a similarly elongated aperture, shell whereas their mantle cavity Only in is very deep and the gill correspondingly more highly developed opisthobranchs can the greatly enlarged and perfected, mainly in the notaspideans; hand, in nudibranchs structures. in made extremely simple leaf-shape in contrast to cypraeids and its marginellids, the large. gill followed by the supraintestinal ganglion and as a result the An is become reduced and can be replaced by other anterior pedal gland, as in prosobranchs, cephalaspideans. the normal it gill on the other The buccal mass of actaeonids condition of the prosobranchs, it is is also present in very different from lacks the characteristic cartilages in the tongue. Remarkably large are the differences between the radula of the actaeonids and that of families most closely related to central plate is plates, it, which a in sometimes lacking, sometimes well developed; the lateral which are only weakly developed and without cutting edge in Toledonia, are completely lacking in Newnesia, likewise in sacoglossans, on the other hand they occur in considerable number anaspideans, notaspideans and some nudibranchs. In the in atyids, series of doridaceans, the central plate often disappears, whereas in aeolidiaceans the lateral plates tend toward reduction. 1623 Even actaeonids as a whole stand at the base of the phyletic if the development of the opisthobranchs, they differ from all of them by the non-retractile penis and from the most closely related families by the complete fusion of the pleural ganglia with the cerebral ganglia. The position of the ganglion ring anterior to the buccal most of the cephalaspideans, but posterior to The as in anaspideans. it, mass and acerids atyids in their stomach contains no hard atyids has a sunken spire reduction, the stomach is has shifted parts. The shell and shows already to the actaeonids; of the bullariids and in the latter family distinct equipped with chewing plates; the scaphandrids which Philinoglossa perhaps forms an are related to the philinids, of shoot with completely reduced to that retained ringiculids and the genus Toledonia have a distinctly elevated spire and stand close still shell. The animal of Paraplysia is off- similar of Haminea, the small posterior tentacles correspond to lobes of the cephalic shield; certain affinities with the anaspideans are by the acerids and according which by is it is however entirely to Odhner different. also It shown also by diaphanids, the radula of is to be assumed that the thecosomate pteropods have branched off from the cephalaspideans, their operculum indicating a relationship with actaeonids, but the latter have no parapodia and have a closed sperm duct; the radula of Spiratella is that of Toledonia. The Pterota are ranked with the They have variously differentiated in several developmental series. One of them begins with Pneumodermopsis, the hook sacks and gills of which are little developed and whose suckers lie directly on the pharyngeal wall, whereas the other genera of the family are more highly comparable to anaspideans. developed. Cliopsis may be close to pneumodermatids, but it has a long proboscis without suckers, with short hook sacks and a rudimentary median lobe of the without special median and lateral clionids and the head which foot. organs, Notobranchaea has a weakly developed pharynx very weak hook sacks and well-developed lobes of the foot; more modified not delimited is coming close to them are from the rump, with hook sacks and pharyngeal vesicles and with epidermal pouches for the foot and the Anopsia part is the thliptodontids with a highly developed fins. greatly divergent because of the development of the anterior of the rump, into which the head can be withdrawn, because of the lack of special pharyngeal organs and hook sacks and, besides certain anatomical differences, also by viviparity. Laginiopsis seems to be a very divergent There form. is hardly any doubt that the shell-bearing sacoglossans are close to the cephalaspideans and possibly nearest to the Diaphanidae of which Newnesia course several is similar in the form of the shell and the radula; of organs have undergone considerable modifications, the 1624 ganglia have moved closely together and the buccal crop-like appendage. Opinions vary on the mass has attained a interrelationships of the naked sacoglossans; they are sometimes related with oxynoids, sometimes with aeolidiaceans, but the latter, in spite of their similarity with stiligerids, to be directly related with them; at all events the nervous system of the naked sacoglossans agrees with that of the shelled ones and do not seem the caliphyllids can be considered as transitional forms. In the nervous system of the notaspideans a tendency is seen toward shortening of the cerebral commissure, whereas the pedal ganglia apart, move close to the cerebral ganglia, and the parietal and visceral come ganglia fuse with the pleural ganglia (notoneury); the same condition is the shell-less Doridacea and Aeolidiacea, which accordingly shown by main difference is the absence one can assume that the closest relations of pleurobranchids had a similar body form without a gill; this applies best of all to Doridoxa, a small Nordic form, which could perhaps dispense are related to notaspideans. Because the of the with the lateral gill gill, because of its small size. In this form, the anus still lies margin of the notum, the buccal mass contains strong jaw plates and a radula with strong central plate and several simply pointed lateral plates. The Duvauceliidae are placed here because of the position below the 1099 right of the anus on the right side and the condition of the jaw and the radula, and are considered as intermediate between Doridacea and Aeolidiacea. Their dorsal appendages are often similar to those in Dendronotus, whereas in most Doridacea they are arranged around the anus, which lies among them Bathydoris is a related form. The in the mid-dorsal line; radula of the others has no central plates, in Dendrodoris and phyllidiids it has disappeared. The development of gill latter family differs from all Doridacea by the lamellae below the notum. Odhner wants to group the families Heterodorididae, Doridoididae and Arminidae together as Arminacea and places Goniaeolididae, Charcotiidae and Heroidae close to them, on the other hand he places the genus Notaeolidia as the sole among the latter he considers representative of Notaelidiidae in Eolidacea; the Coryphellidae (= Flabellinidae) as the most primitive with the anus situated on the right, the anus, the rest of Eubranchidae and Cuthonidae have an acleioproct them have a acleioproct one. The Dendronotacea include the Dendronotidae, Duvauceliidae and Dotonidae. Among the Aeolidiacea, which differ by having separate liver branches and in most cases cnidosacs, the Arminidae have a more or less broad notum, on the underside of which gill lamellae are developed in Armininae, whereas the Dermatobranchinae have no gills, likewise Doridoides, the Hedylidae, the Phyllirrhoidae, the Goniaeolididae; in addition the dorsal appendages which are developed in place of gills are 1625 at times hardly indicated. The form and arrangement of such appendages is varied, sometimes being combined groups and born on smaller or in 544 and 552). The radula occasionally larger stalks (cf Figs. on several lateral plates, in others only one either side and has still in the families Tergipedidae, Fionidae, Aeolidiidae and Myrrhinidae, they are completely In absent. Calma forms a continuous series of denticles radula the resembling a bandsaw. The tethyids lack a radula. The naked opisthobranchs from the normal condition of phyletic series, so that there class. A as a whole more or less is no doubt about widely diverge with them through snails, b,ut are related their belonging to this them is uncertain, as for instance Rhodope, which at any rate has to be considered closer relationship of a few of Vayssierea and especially as a highly simplified nudibranch without shell, foot, radula, liver and heart; the position similar to the of the genital opening and anus on the right side is condition in nudibranchs and prohibits affinity with turbellarians with which a close relationship, as assumed by Jhering, is completely out of the question. The most primitive pulmonates As in the latter, annulled, the eyes cavity, the on the mantle left side, ureter, the the aperture has a lower lobe and contains a gland at the radula bears gonad commissure has been the head, a small osphradium lies in the mantle lie in of thin rodlets, the ventricle no are closest to the cephalaspideans. crossing of the visceral the numerous small hermaphroditic, is plates, the widely united with one another, the its ? efferent ducts are It among opening by a seems appropriate those which still to less is connected with the look for the most primitive pulmonates show connections Some to ellobiids, have become entirely land-dwelling, but most the An operculum, which is sea, such as the such as the Carychiinae, live on the sea shore; shell with the columellar folds is similar to that in is still more or ciliated groove. Actophila and Amphibolacea. 1100 consists kidney has duct stands in connection with glands and a bursa copulatrix, the invaginable penis genital jaw lies posterior to the auricle, the their some cephalaspideans. absent in ellobiids and in all retained only in the brackish- water amphibolids. other pulmonates, A transition brackish water into the rivers has happened easily and hence from among the inhabitants of fresh water there are very primitive pulmonates, such as the chilinids. The amphibolids differ from ellobiids by the common genital openings with closed sperm duct and the long glandular tube on the penis, and by the absence of a bursa copulatrix; contains no to the gill rather but far is filled their mantle cavity with water, a small osphradium lies close forwardly situated aperture. They represent a small 1626 removed from which opisthobranchs were placed in the by seashore. They live on the also The considered them as pulmonates. Pelseneer zoologists, but some mantle cavity of Gadinia is without a gill, on the other hand in Siphonaria several gill lamellae are developed; in the latter the two offshoot from the pulmonate stem. Even more distantly this stem are the gadiniids and siphonariids with cup-shaped shell, genital openings are united. Distinctly developed cephalic tentacles are absent in these groups, as in As in ellobiids, the shell many cephalaspideans. of Chilina as a rule has columellar folds, the opening of the mantle cavity nervous system is 1 or 2 distinct rather wide, the by the length of the visceral commissure, shows an indication of the crossing. This South characterized is which occasionally still American group on the whole the most primitive among pulmonates is form of the radular plates evidently appears living in freshwater, the be less primitive than in lymnaeids, them have still not acquired a which stand close gill to them. to Both of formed by expansion of the lower mantle lobe, as in planorbids and ancylids, and the physids approach them is New The in this respect. Zealand Genus Latia, the shell of which similar to that of Septaria, has a radula similar to that in Chilina, a commissure, widely separated genital openings, a rather long visceral short oviduct with a large bursa copulatrix and a long closed sperm duct with prostate a at its initial position. The physids agree with the planorbids in the sinistral shell and the awl-shaped tentacles, whereas the form of the radular plates is more similar to those of Chilina; the reproductive and digestive organs also betray affinities with planorbids. Aplexa does not have such mantle lobes as Physa; arises close to the its bursa copulatrix opening of the oviduct, and the prostate lobules are also closer to the opening, hence Physa is somewhat more modified than Aplexa. The lymnaeids are also closely related to chilinids, their radular have a more primitive form, plates their oviduct has a shell between the albumen gland and uterus, the prostate and Erinna the spire is is gland massive; in Myxas very small. The North American genus Lanx represents a very unique offshoot with cup-shaped shell similar to the ancylids. The openings of planorbids always dextral; among them the mantle cavity and the genital openings in on the lie left side, even when the shell the genus Isidora has the with more or less high spire and left aperture, is most primitive apparently shell form Miratesta stands here, then follow the disk-shaped forms, and finally the forms with the aperture on 1101 the right side, the spire of which that it is to be visualized as so deeply sunken projects on the original underside. Segmentina ridges Among in the interior is characterized by of the shell and the appendages on the penis. the ancylids, the Ancylinae are to be derived from Isidora, with 1627 the whorls of the Correlated with this is approach of the heart in becoming reduced and the aperture widened. the reduction of the mantle cavity and the shell to the gill and the tube-shaped multilobed kidney; Ancylus fluviatilis the long sperm duct at its beginning has a prostate with few lobes and the penis has a long and thin process. how uncertain as to The the seems the Acroloxinae are related to the Ancylinae. ellobiids are placed, mainly development phyletic It of the by Pelseneer, at pulmonates, the beginning of and not only of basommatophorans but also of stylommatophorans. The genera differ considerably from one another not only in the form and size of the shell, but also in the radula and the genitalia. The radula of Carychium, the plates lateral the of which have small inner and outer accessory cusps and marginal plates have broader finely denticulated cutting edges, corresponds most with the form occurring in several other groups of pulmonates. Marinula and Pedipes have similar dentition with numerous narrow plates most cases with 2 cusps. The radular plates, the lateral plates in of Ellobiinae become stronger with increasing body cutting edges become large and simple, but that size, their of the central plate often remains small, and accessory cusps can be retained on the marginal The jaw, plates. stronger, in weak in Carychium, also becomes gradually becomes a thick, smooth body similar to still Ellobium it stylommatophorans. The genital they show tracts are also different, but in Pedipedinae a less primitive condition than in Alexia, with the glandular hermaphroditic duct terminally dividing into an oviduct with a longstalked bursa copulatrix and a sperm duct, which opens in a ciliated groove anterior to the opening; posterior to the end of the penis begins the terminal part of the sperm duct which leads into the inner end of the penis. Carychium has a completely closed sperm in Alexia, the genital bursa copulatrix largely closed duct or is at the end; the at is duct. duct. On the other hand, hermaphroditic up to the end, where the attached, and is sperm hermaphroditic duct combine duct In is connected with the penis through a Tralia and Melampus the glandular which however short and divides into 2 ducts, bursa copulatrix is attached to the hermaphroditic the beginning of the oviduct. In Ellobium, below the albumen gland, a glandular duct separates from the hermaphroditic duct, although the two then combine again and near the opening have a very longbursa copulatrix. Whereas vagina as in actaeonids is in most stalked cases lacking, it is developed in Marinula and Carychium, a fact which brings them closer to the stylommatophorans. After an examination of Alexia, Pelseneer emphasizes the following characters by which it approaches the stylommatophorans; an indication of anterior tentacles, absence of a "Pavilion respiratoire" (lower mantle 1628 lobe), missing osphradium, single dorsal jaw, long esophagus into the posterior end of which opens the anterior liver lobe, and an anterior pedal gland. On the whole, however, Carychium probably stands closest to the most primitive stylommatophorans. Whereas in Ellobiinae the eyes are situated in the head posterior to the base of the tentacles, Otina has only hemispherical processes in 1102 which the eyes are contained. The shell is relatively small with rapidly increasing whorls and a wide aperture without columellar folds; the foot, divided by a transverse furrow, is similar to that of Pedipedinae to which Otina perhaps stands closest; the sperm duct is completely closed. The main difference between the stylommatophorans and the basommatophorans is usually considered to be, aside from the mode of and the position of the eyes, the union of the two genital openings, which are more or less distantly removed from one another in life basommatophorans, with the exception of amphibolids and siphonariids. In this respect, standing close to the latter are the "Ditremata," as the group of completely snails shell-less soleoliferans has been comprising the oncidiaceans and At called. Their phyletic affinities are uncertain. any rate they have separated very early from the other pulmonates. Because the oncidiaceans are shore dwellers, they from shelled littoral may have developed forms, somewhat similar to Otina, by reduction of the shell, elongation of the eye-bearing tentacles, and the lung opening shifting posteriorly along with the anus, the kidney opening. On and the ? genital the other hand, the soleoliferans have completely moved to land; they have become greatly elongated and their very narrow foot has acquired numerous transverse ridges; their mantle cavity on the lie is considerable differences, these two groups be recognized, so the still right side (Rathouisiidae); but, in vaginulids the intestine and the ureter have lengthened posteriorly within the notum. to reduced and intestine, the kidney and the oviduct originally the openings of the that they can body of which was still still In spite be derived from common ancestors, not so elongated as in soleoliferans lung, kidney and ? opening lay on the of permit a certain relationship right side. The and the reproductive organs of oncidiids and rathouisiids are essentially similar; noticeable is the presence in both families of unique penis glands, which however are apparently independently acquired in each, although an indication of this may already have existed in the common of vaginulids are already indicated in stem form, just as the glands Vaginina. Among rathoudiids, the genus Rathouisia, the form of which resembles that of most vaginulids, is probably more primitive than Atopos, which has Because this family probably has a predatory lost the lateral edges. mode of life, its buccal mass resembles that of some other predatory snails without a relationship — 1629 existing between them. The rathouisiids and vaginulids have at all events evolved from the same stem forms, which already possessed the peculiar notum and a highly concentrated nervous system closely embracing the esophagus; the lung cavity was reduced, it lay on the right side, where the kidney of rathouisiids opens; the tentacles could not be retracted. Succinea been has in most cases considered a primitive its amphibious mode of life, very stylommatophoran, mainly because of wide it should not be brought into genetic connection to Lymnaea; Pilsbry considered shell and incomplete separation of the genital openings; distribution, although an independent branch of the pulmonates. The weak it can be considered an indication of degeneration in contrast to the forms with stronger shells, succineids are close to expressed by Odhner 1103 and so one could reach the conclusion that the Such an opinion has been a higher group. who assumes a relationship between succineids and the Amphibuliminae, to which he allocates the The resemblance of noticeable; the kidney of the West African genus latter to that Aillya. of Succinea is furthermore the shell, the intestine, the musculature, and probably also the nervous system, are similar in the genitalia, Succinea has retained a prostate, which lacking in bulimulids, is "elasmognath" jaw. Moreso than in Succinea, the shell become smaller and so that flattened, it an also as of Homalonyx has covers only the viscera, in Neohyalimax it is completely enclosed by the mantle, similarly in Hyalimax. The shell of athoracophorids is completely rudimentary, and because the mantle cavity also has become greatly reduced, developed it has unique processes. The kidney, as in Ancylus, has developed its The jaw indicates a relationship with some similarity with Hyalimax; the from those of succineids by the shortly penis and vagina open into a more or less a long many-shanked ureter. succineids and the radula has distinguishable genitalia are stalked bursa copulatrix; the long vestibulum genitale. Even if the succineids are not regarded as primitive stylommatophorans by Odhner, this could perhaps be true of the Achatinellacea, which show strong similarity with ellobiids because of columellar folds of the shell 590); they also have a rudimentary jaw and a straight kidney without ureter. Among them most the of the tornatellinids like many (cf. Fig. vertiginids and some subulinids have a lamella on the penultimate whorl (parietal lamella), achatinellids. The radular plates do have some it is lacking in the similarity with those of Actaeon, but this cannot be considered as an indication of relationship nor is there any with the athoracophorids — but development and, compared with the vertiginaceans, as an etc., analogous as deviating from the normal form. The genitalia show some differences; the sperm duct soon separates from the oviduct, the bursa copulatrix is long stalked; 1630 the often very small development of the development of the prostate and of considerable often size. albumen gland and the strong striking; the Pilsbry appendage of the penis considered the is tornatellinids, and amastrids to be very old and assumed their common from an extinct group, which is also related with the Vertiginacea and Achatinacea (Ferussaciidae); it may well have been the ancestral achatinellids origin form of the stylommatophorans. The shell form in the family of the amastrids Leptachatina approaches Cochlicopa, Carelia is is highly varied; high-spired like achatinids, whereas Pterodiscus and Planamastra approach disk-shape; hence from the shell form alone no conclusions regarding relationships can be drawn. In general the following may be considered characters of primitive organization: a kidney without "secondary" ureter and simple genitalia of varied development of different parts can and a normal radula, the plates of which times can undergo small changes through the loss of which however, as the show some result differences; nevertheless at accessory cusps or through secondary cusps of the marginal plates. The modifications occurring in different families are sometimes so similar that one can be in doubt whether these are to be considered as signs of relationship; this is true of the shape of the shell, the nature of the radula, the presence of a "secondary" ureter and of certain accessory glands or appendages of the genitalia. 1 104 The small genus Pyramidula, with broad cone-shaped, umbilicated from Vallonia by the absence of an appendage on the penis and from endodontids by the absence of a ureter; on the other hand the shell, differs genitalia are so similar to those with the The latter genitalia and may of Columella that it seems to be related represent the most primitive form of Vertigininae. of other subfamilies present considerable differences; the Pupillinae like the valloniids, the achatinellids and amastrids, as well as the Eninae and Napaeinae, often have a very long appendix on the penis, is in most cases bifurcated; the bursa copulatrix most cases has a long simple stalk, in pupillines and enines with a spermatophore sack. Can the strongly developed appendix in these groups be considered homologous and hence can they be considered as the retractor of which in one another? More recent investigators, such as H. Watson and Steenberg, seem to assume this; in that case the Pupillinae would have to be separated from the vertiginids as a special family and would perhaps have to be derived from valloniids, to which the other directly related to families with appendix may be joined. On the other hand, the Chondrininae and Orculinae may have developed from Vertigininae through the stronger development of the epiphallus which sometimes has an appendage, whereas other parts, such as the prostate, the radula and the shell, have 1631 also undergone certain modifications. In the family Enidae, which perhaps are most closely related to the Cochlicopidae, a separation of the forms having a spermatophore sack on the stalk of the bursa copulatrix from those without such a structure would perhaps be without significance, but all of the mainly African genera seem to lack this appendage. Their with Napaeus, Napaeopsis and Spelaeoconcha seem uncertain, affinities MauronaThe absence of an appendage on the penis in Chondrulinae is now to be considered as a secondary phenomenon. It is remarkable that the genitalia sometimes show distinct differences while the shells are very similar, as in Zebrina, Zebrinops and Adzharia, and also in Napaeus but they are not closely related to the North African groups paeus etc. and Napaeinus. Whereas the oviduct in valloniids is simple, in Chondrininae and is divided and one part, which contains another type of it gland, forms a blind sack. A similar division by means of a fold, in and Orculinae free margin of which the sperm duct runs, clausiliids. On is also found in enids and the other hand, Steenberg believes that he finds so much overlap in the structure of the gonoducts of Lauria and Balea that he would the clausiliids much seems ureter, form between "Orthurethra" and Whether (Sigmurethra). or not this view is accepted, this like to regard it as an intermediate correct that the clausiliids, in of spite their "secondary" have developed from enids or vertiginids. Judging by the nature of the penis, with an epiphallus which often has a small process, but without long appendix, and by the presence a spermatophore sack on the stalk of the bursa copulatrix, the clausiliids The normal radula agrees in would stand close to the Chondrulinae. the two groups, only the genus Peruinia having acquired a strikingly different dentition. The interrelationships of the subfamilies and genera are still poorly clarified; it appears uncertain whether the presence or the absence of a spermatophore sack but the Neniinae may be less primitive than the is primary; Phaedusinae, and also the purely glandular nature of the process on the stalk of bursa copulatrix in Clausiliinae may be a secondary condition in comparison with the Cochlodininae; a similar condition exists in the case of the apertural folds of the 1 shell, The 105 which occasionally become rudimentary. phyletic origin of the Achatinacea seems to be highly enigmatic. Pilsbry thought that they have developed in Africa and that they are related to clausiliids, but the latter have also in other respects few connections to Africa and such a relationship appears uncertain. The Achatinacea differ from most of the Orthurethra by the lack of an appendix on the penis, agreeing in this respect with the Vertigininae. The similarity of the shell with tornatellinids and Carelia cannot be interpreted 1632 as a sign of relationship. The radular plates of the primitive achatinaceans have outer and inner accessory cusps like the endodontids, and also the kidneys of ferussaciids and the lower endodontids show a certain resemblance; moreover one can point to the of Ferussacia, and because lateral furrows on the foot the genitalia are also similar, the stirps of the Achatinacea seems to stand closest to the endodontids, although these in most cases have low-spired shells, but great significance need not be attached to this circumstance. It should be mentioned here that Semper was struck by the similarity of the dentition, of which he says: "the form of the radula places especially the Philippine species (End. too philippinensis) in the closest vicinity of the subulines, tornatellines, on account of the inner apertural teeth, designated as a flattened tornatellines"; these endodonts at this point however etc.; could be it should be remarked that Semper, because of insufficient knowledge placed the tornatellines near the subulines. Among the achatinaceans, the small ferussaciids and subulinids are few of them attain considerable size, many of them are very highly turreted. Near them are the megaspirids, which in most cases have internal lamellae in the shell, in addition the achatinids, of which some species attain very considerable size, and also the oleacinids, which have shifted to a predatory mode of life. There are Pseudosubulina species in which the shell is hardly different from Subulina; a jaw is still indicated and the radula bars small plates with 2 cusps; the genitalia show a long and rather thick vagina, long-stalked the most primitive, only bursa copulatrix and a very short penis. In this family the animals in most cases become larger, with low-spired become much smaller than the animal; shell, the which foot in Strebelia enlarges, has jaw become the becomes rudimentary, while the simply pointed radular plates stronger; the genitalia show some variations, an epiphallus may be absent or present, as also an appendix on it or on the penis. It appears uncertain whether the testacellids stand close to the oleacinids; the small shell situated on the posterior end and the arrow-shaped radular teeth remind especially of Strebelia, but no direct relationship exists with the latter. The group of the endodontids plays a very important role in the phylogeny of the pulmonates. The kidney does not have the straight form as in the "Orthurethra", however some primitive genera do not show the S-shape of the "Sigmurethra", and the kidney and ureter are strikingly variable, so that one can assume which gradually lead cases the kidney that here a to the formation development has just begun, of a "secondary" ureter. In is distinctly shorter than in "Orthurethra", most and the ureter does not reach to the mantle margin, sometimes opening into the posteriormost part of the lung chamber; as a rule however its terminal part 1633 has approached the intestine, a condition which in "Orthurethra" is introduced by reflection of the terminal position but because of the it has not reached the base of the lung chamber and The common ancestors of the endodontids and the Orthurethra length of the kidney 1 106 the intestine. Pyramidula and Vallonia) probably had only a moderately elongate (cf. kidney (cf. which has further developed differently ellobiids) in each of these groups. radular plates of the oldest endodontids had the primitive form The weak jaw consisted of jaw have already modifications withm the family. The modifications of its height, which is unusual only in Phenacharopa (cf. with an inner and outer accessory cusp, and the a few separated undergone further the shell relate to Fig. 657), the provision appeared in a radula and the but the platelets, of the aperture with teeth (cf. Fig. 658), few genera, and the reduction known only The foot has a lateral furrow are seldom developed. One can assume that on from either side. this which in Ranfurlya. Appendages on the genitalia widely distributed group in different ways most or all pulmonates that are not "Orthurethra" have developed. The lateral furrows of the foot can be retained or become indistinct, the assumes various forms, as also the radular shell plates; the ureter in cases reaches the mantle margin, and the genitalia also more or series less striking modifications. have thus whereas arisen, the origins their terminal show so much such foot. lateral present considerable differences. Fig. 662), the polygyrids and sagdids similarity with helicids, that they considered close to the on the (cf. Of latter, or less richly developed of which stand close to the endodontids, may forms Like some endodontids Some more most may undergo have been in most cases especially because they lack lateral furrows the corillids, the South African Sculptaria species have furrows, whereas they are lacking in Plectopylis and Corilla; the latter are distinguished the Asian genera by lamellae in the interior of the shell. The zonitids are closely related to certain endodontids and distinguished from them mainly by the long, as a rule simply pointed marginal plates of the radula, such as those exceptionally occurring also in some endodontids; developed on the d" in the Gastrodontinae a calcareous spine has copulatory organ. Daudebardia is characterized the small shell borne only on the posterior end of the animal, and also the large radula with claw-shaped teeth; is hardly to be doubted. The same is relationship with the zonitids its to be assumed of the American systrophiids. In a different direction, the vitrinids zonitids by a reduction mantle lobes over the in the size shell; in of the by by shell, the genus have developed from having more or less large Vitrina, glandula amatoria appears in or on the vagina. a variously strong 1634 Even more advanced is the reduction of the shell in Plutonia and the arionids, among which only Binneya still retains a Vitrina-Mke shell; in Ariolimacinae and Arioninae it is completely enclosed by the mantle and in Oopelta it has completely disappeared. The philomycids have developed differently; they do not have such a mantle field as arionids, so that their resemblance with vaginulids; they have a wide, body form attains some empty shell pouch; their genitalia have acquired a different structure. Next to vitrinids may be placed also the limacids, of which Parmacella still has a shell with a spiral initial part, which in young animals is not 1107 enclosed by the mantle. yet More doubtful are the affinities of the predatory trigonochlamydids, the mantle of which at times dorsum and the center of the times at The Ariophantacea represent placed near is at the end. similar developmental a series, in which the marginal plates of the radula as a rule bear dicuspid cutting edges 694), their initial forms have shells similar to zonitids and (cf. Fig. simple gonoducts without special appendages; they endodontids, and like some of which attain still stand close to the these are small. Near them stand numerous genera, more or less considerable size (cf. Figs. 685 and 688), the shell being well developed and able to harbor the entire animal. becomes weak and small as in Vitrina enclosed by the mantle and becomes rudimentary as in In contrast, the shell in other series and is finally On limacids. the other hand, some groups an accessory in provided in most cases with a has developed; stylet, gland, among the Helicarioninae and the closely related Urocyclinae this gland occurs only in a part assumed of the genera, that ancestors; but in it in these cases hence variable development, has not been it may be homologous in inherited it from is to be common Macrochlamydinae, Ariophantinae, Xestinae, Sophininae and probably also in Girasiinae and Parmarioninae; it is uncertain in the case of Durgellinae and similarly in Staffordia, the gland of which The is very peculiar. phyletic origin of Acavacea is still view that they derive from Polygyrids has the latter live in America. quite uncertain; little Pilsbry's substantiation, because One may perhaps assume that in "Gondwana- land" under the especially favorable living conditions the endodontids attained a considerable size increase without in their organization; that along larger, showing great modifications with the shell the that the lung chamber had little embryos also became depth and hence there was increased branching of blood vessels and the kidney without first became shortened acquiring a ureter; and that the radular plates still retained inner and outer accessory cusps, and the gonoducts remained simple. While then these animals spread over the lands of the southern hemisphere, they partly changed considerably under other conditions, which is 1635 became turreted on the The radular plates already evident in the form of the shell, which one side {Clavator, Fig. 702) or very low on the other. in most cases lost their accessory cusps and sometimes acquired long, Occasionally a ureter has developed, which pointed cutting edges. reaches the intestine. The genitalia have also in Caryodidae; this Australian group is become modified, hand the South African genus Trigonephrus seems modified, with — the gonoducts. be the to least roundish shell, radular plates with accessory cusps, a kidney the anterior end of which to Orthurethra especially the most divergent, on the other is curved toward the intestine — similar but without a ureter, and without special appendages on Dorcasia, with a low shell and unicuspid central and lateral radular plates of the radula, stands near Trigonephrus. The South American strophoehilids are also little different from Microborus being only somewhat higher; some species size (cf. Fig. 704). this, the shell of attain considerable The Chilean Macrocyclis has a shell form similar to it seems doubtful. Very different Dorcasia, but a direct relationship with has been the development of the Acavacea living in Madagascar, which also include the turreted genus Clavator. It 1108 will hardly the Bulimulinae, others Figs. (cf. be doubted that closely related to the strophoehilids are among which some genera have similar shells, whereas 707-709) have become highly modified. The dentitions also undergo modifications, of which the considerable broadening of the cutting edges (cf. Fig. 710) needs to be highlighted; the condition of the kidney is also different. Because Partula has a straight ureter, placed near the achatinellids, however, the genitalia appendix, short-stalked bursa copulatrix much more family, but the latter Partula — — have so with Placostylus subgenus Diplomorpha has a the anatomy of which is (cf. shell unfortunately little Figs. — it penis has been without similarity with that 713 and 715), and very similar to that of still unknown. However Pilsbry also recently declared the similarities of Partula with bulimulids to be a mere analogy and not a sign of relationship, which is contradicted by the kidney form and the lung without distinct blood vessels. How these Melanesian genera and the Australian genus Bothriembryon are connected with the American ones can hardly be explained otherwise except by migration from South America toward the west across the It is also to be assumed that the Odontostominae and Orthalicinae are closely related with Bulimulinae. Less certain is the then-existing land bridges. relationship of the latter with the Amphibuliminae, because their anatomy known. Pilsbry took them for bulimulids with a more or less reduced shell and supposed that they have developed in 2 lines, in which is still little Simpulopsis and Peltella are being closer to Drymaeus, whereas Amphibulima and Gaeotis being closer to Bulimulus; Odhner, on the 1636 other hand, believed that Simpulopsis stands closest to the root of the bulimulids as well as that of the succineids. This view would hardly permit the strophochilids and bulimulids to be designated as related and, contrary to current opinion, would consider the thin and only slightly coiled shell as more primitive than the normally developed one. At all events, Peltella and Gaeotis are extremely developed forms with a small more or shell covered by the mantle; the less genus also with latter greatly broadened cutting edges of the radular plates. Also to be derived from bulimulids are the cerionids, with a normal radula and a long blind tube on the stalk of the bursa copulatrix, and the urocoptids, of which the Eucalodiinae have a very high-turreted shell, but originally a similar radula and the bursa —have — except for the missing blind tube of genitalia similar to those of cerionids; in the shell form the nearly disk-shaped Hendersoniella differs strikingly from the other Eucalodiinae. The Microceraminae and Urocoptinae have undergone modifications of the dentitions cutting edges of the much more or (cf. less Figs. 727, 728), in the latter the numerous have become lateral plates enlarged and the outer cusps are displaced forward. home of If the original the Acavacea lay in the Indian region, one can assume that the helicaceans which stand in close relationship to the former, also originated there; this applies mainly to the pleurodontids, which have spread not only across southern and eastern Asia and Australia, but also to northern South America and Central America, becoming more or in less their organization; Eurycratera (cf. Fig. modified in their external appearance as well as forms such as Camaena 732) may be Fig. 735) and on the other hand (cf. the most primitive; the highly variable Papuina, near which stands Cryptaegis with a thin shell completely enclosed by mantle, as well as Amphidromus and Calycia, the radular plates of which have broadened bi- or tri-lobed 1109 cutting edges, seem to be most highly modified. Near the pleurodontids stand the fruticicolids in which a "love dart" has developed in a sack- shaped process of the vagina in association with a gland. Among them, Helicostyla, native mainly in the Philippines, with small dart sack and simple gland, branched off early. The others became widely distributed, undergoing various modifications; the Fruticicolinae mainly across Asia, close to which may stand the few East African helicaceans; the Epiphragmophorinae have migrated eastward to America, and the helicids westward, where they have spread across Europe, North Africa, and the Atlantic islands. less The some helicaceans the "secondary" ureter is more or incomplete. It is also very probable of the Streptaxacea that they originated from endodontids. In the family Haplotrematidae, which according to Baker 1637 belongs to this stirps, the ureter is short and opens at the base of the mantle cavity, the genitalia have no special appendages, the radular plates claw-shaped, a weak jaw strong, are manner American family this is still is present. related with paryphantids In what and streptaxids appears uncertain; Baker also states that they are perhaps polyphyletic, emphasizes the similarity of the shells of South American Austroselinites species, which however have not been studied anatomically, but with New still little-known genus Priodiscus stands isolated and Zealand paraphantids. In the last-named family, the anatomically Some of uncertain. the species placed by Kobelt endodontids, and the similarity of the shells The dentitions show differences, may its affinities Ouagapia in point to a relationship. which permit one to conclude closer Ouagapia relationships between certain genera; thus the plates of Delos, and Diplomphalus resemble each other is lacking; of these, the last-mentioned The closer relationship of Schizoglossa, (cf. Fig. may be are are rather 766), and a central plate the most extreme form. which also has no central plate, seems uncertain; on the other hand, Paryphanta, Wainuia and Rhytida have more claw-shaped plates and a central plate doubtful (cf. Fig. 768). Borneo has not been anatomically investigated; Kobelt wanted a series of Rhytida species from Melanesia, New here," but he also included South African species. Conolly) Highly the group Macrocycloides, the typical species of which from is to "insert Zealand and Australia One of these {tarachodes noticeably distinguished from Rhytida by the shape of the is radular plates (cf. Fig. 765) and perhaps stands closer to Delos; recently H. Watson has erected the genus Nata for Among the Streptaxacea, the small, may be living in the Seychelles, anatomy of Augustula, knowledge of which we for the it. low-spired forms currently considered the most primitive. Of the unfortunately imperfect anatomical are obliged to Wiegmann, the following are to be emphasized: the "foot with double broader," a relatively large right "neck lobe" on the mantle margin, the large median radular plates, the arming of the penis, the neck of the uterus, and the short bursa copulatrix with "thorn-shaped stimulatory papillae." Wiegmann regarded this snail form from the hyalinias to the agnathans," however the zonitids probably cannot come into consideration, but rather the as a "transitional endodontids. The genus Imperturbatia has its 10 embryonic shell is a dentition similar to apertural margin reflected, in the interior with the repeatedly invested apertural margin. Martinella is streptaxids 1 or 2 small warts behind Because the South American one may assume that these two genera were connected and then went extinct in the intermediate strikingly similar, in earlier times some smooth, the other whorls strongly ribbed, the 1638 lands. Acanthennea, living in the Seychelles, agrees with Imperturbatia and the small interior warts and may have arisen from by elevating the shell. There is no doubt that other streptaxids have developed from low-spired forms, because they in part have such shells permanently and in part only in the young stage. At the same time there is also a tendency toward the development of turreted or cylindrical in the strong ribs the latter more or shells, often also a less strong development of apertural teeth, Africa. especially in Looking back, one may assume the that ancestral stylommatophorans had a small, moderately high-spired form of the and an shell organization which was transitional between Pyramidula, valloniids and most primitive endodontids, and the from that by this, differentiation of the radula, the kidney and the genitalia, these 3 groups and then the various branches of the stem developed. characteristic of some groups, may at The furrows of the foot, lateral times have become reduced in the course of the phyletic development, as such are developed in the ferussaciids, but are not recognizable in subulinids. The scaphopods have sometimes closer to times been placed closer to the gastropods, at the bivalves; it is fruitless quarrel to about it. which is transitional between gastropods and bivalves. From the common stem forms, they have still inherited a snout-like head, which contains a buccal cavity with Without doubt they represent a separate class, subradular sense organ, jaw and radula, whereas such has been lost in the bivalves. their that But like bivalves, they have retained the original nervous system of bivalves and — is aside from the buccal ganglia — is symmetry; very similar to very different from that of zeugobranch gastropods. Their foot has no sole, but rather serves for burrowing into the substratum, like in nuculids; it is however to be assumed that this form of the foot has been independently acquired by the scaphopods. Both ctenidia of the stem forms have disappeared and in connection with this, the heart blood vessels are imperfectly developed. The shell becomes initially and saddle-shaped by fusion of the ventral margins, whereby an from the posterior one; the mantle cavity from that of zeugobranchs. As a result of the more or ring-like anterior opening is separated is very different less strong elongation of the animals, certain organs, mainly the gonad, have moved to the back, and the pericardium also As no trace of an epipodium the lies posterior to but the cirri serving to obtain food, and the shield-shaped folds bearing them, may rectum. in bivalves, is left, correspond to the head fold and the cephalic tentacles beset with cirri of zeugobranchs. Because to date only a few species have been anatomically studied, nothing can be said about interrelationships of the groups that have been 1639 may assume that the the very much elongated based on external features. However, one short forms (Cadulus) are more primitive than Among the bivalves, the nuculaceans are ones. most cases regarded as the most primitive, mainly because of the form of the gills, which is similar to that of zeugobranch snails, as well as because of the separation of the pleural ganglia; at the same time it must not be overlooked that certain characters of their organization make it in impossible to derive other more primitive bivalves from them, especially the arcaceans, which are in some respects. Both stirps have taxodont hinge margin, and hence one can designate that taxodonts as the most primitive bivalves. It is, however, noteworthy that the embryonic shell (prodissoconch) of the taxodonts does not yet show the anlage of the hinge teeth, but that the hinge margin provided, anteriorly and posteriorly of the small ligament is only with transverse grooves, whereas the teeth appear only later below this grooved margin. The question now arises as to the significance of these prodissoconchs for the phyletic development of the bivalves and whether there are mature species which correspond with stage. The latter this ontogenetic The genera question has to be answered affirmatively. Hockstetterina and Adacnarca, and also the mytilid genera Idasola and Dacrydium, have such grooved hinge margins without forms then be considered as the to Pelseneer, the animal small anterior and a initial Can teeth. these forms for the taxodonts? According of Adacnarca has a completely open mantle, a larger posterior adductor muscle, the foot posteriorly prolonged lobe-like and contains a byssus, the visceral is very small, only the posterior pair of the labial palps intestine short and straight, the gills are broad, is only the outer gill is is mass developed, the composed of filaments, laminae with ascending limbs, they do not reach to the labial palps, the kidneys are simple sacks separated from one another, the gonads are ventrally united with one another, their efferent ducts opening separately from those of the kidneys. Although such an organism shows many primitive related with Limopsis, characters, there and is no mistaking that the absence that of hinge teeth it is is closely probably only a consequence of the small size under the severe living conditions in the Antarctic; hence Adacnarca can hardly be considered a preserved form, but as a sexually mature larval ancestral form (neoteny). In comparison with the ancestral conchiferans, the mantle margins have become greatly cover the gills, expanded in conjunction with the shell, so that they and, after the shell had divided along the median line, could enclose the entire animal. Consequently, the head along with the pharynx became reduced and ingestion of food had to take place different way. In nuculaceans the labial palp this purpose, which may correspond in a appendages were used for to the cephalic tentacles of snails, 1640 but in most other bivalves food particles were led to the by ciliation of the broadened gills and of the mouth opening labial palps. doubted that the hinge margin was originally stretched It cannot be straight; probably body had a considerable width and a moderate height, which would lead one to decide on such a form as Area. The foot had a sole, which could be used for creeping, but in a fashion similar to janthinids produced a glandular secretion (byssus), with which the as in gastropods, the animals attached themselves to stones, etc.; on the other hand, in nuculaceans the foot was used for burrowing in soft substratum and the became reduced. This form of the byssal gland primitive than that of arcids. foot is certainly less Also apparently correlated with the production of the byssus are the strong muscles, extending from the byssus groove to the and these may be the reason for the urogenital shell, organs remaining widely separated from one another; hence not only the gonads and kidneys were paired, but also the pericardia which originally 1112 connected the gonads and kidneys with one another and were parts of the same anlagen. one assumes In this respect also the nuculaceans are less primitive. If that the ancestral forms possessed not only paired auricles of the heart, corresponding to the two ctenidia, but also paired ventricles and aortae, one can easily visualize the posterior aortae which unite below the rectum as branches of the anterior aortae, and because the anterior and posterior aortae enclose the that with approximation intestinal tract, and fusion of the two it is understandable ventricles, as has taken place in most bivalves as well as in zeugobranch snails, the now single may shift above ventricle is transversed A or below the intestine. does no longer by the intestine; but at times it connection of the gonads with the pericardium but occasionally with the kidneys; but in most cases exist, only their openings are close together. Among the nuculaceans, the 4 families have developed in different ways. Their mantle is originally completely open (Nucula, Tyndaria), but has developed more or less long siphons in the genera Neilonella and Malletia and in the ledids. The hinge teeth are sometimes present only in small numbers, and in Solenomya they have completely disappeared. This genus stands close to the nuculaceans because of the form of the foot and of the gills, and also because of the labial palp appendage and the open statocysts; From such it may be most gills as the closely related to Malletia. nuculids possess, arose those of the arcaceans by elongation of the two rows of lamellae into two-limbed filaments; labial palp appendages are lacking. The foot in most cases has a welldeveloped byssus gland, which produces a simple byssus stem. The kidneys are sack-shaped. Among the arcaceans, the Area species with a long, straight hinge margin and a strong byssus are to be viewed as the 1641 most primitive. Glycymeris has lost the byssus and has a foot similar to that of nuculids, on the other hand Limopsis has retained the byssus; the shell has a form similar to that in Glycymeris, but the anterior muscle has become smaller and small forms, lies higher. Close to which the hinge teeth tend toward reduction and in disappear completely. Following Hochstetterina form, in is is Philobrya, as a terminal which the umbones have shifted forward and the anterior adductor muscle It adductor this stand several is completely reduced. noteworthy that those groups of bivalves which are closest to taxodonts are not related to nuculaceans but to arcaceans; like the they have broad gills composed oft filaments, a completely latter, open mantle, often a well-developed byssus gland, and sack-shaped kidneys. However, the development has taken place very differently phyletic directions. one direction In first come the in main 2 They lack mytilaceans. taxodont hinge teeth, occasionally only a few small tubercles are developed, the shell form of Idasola is Arca-WVe but it is often anteriorly pointed, and the anterior adductor muscle tends toward reduction; the gills are as in Area, the mantle has a closed excurrent opening, the byssus consists of threads. In pteriaceans the straight hinge margin emphasized is at times 799 and 800), the shells are greatly compressed, occasionally inequivalve, the ostracum is made of prisms, the hypostracum nacreous. The umbones have shifted more or less strikingly (cf. Figs. Pinna they anteriorly and byssus sometimes reduced (Crenatula, at is in times smooth, at the pointed anterior end. lie entirely at times folded. Pinna The Vulsella), the gill lamellae are is the most divergent form of this stirps. The pectinaceans, of which only Dimya has adductor muscle, which were living still species may still retained an anterior stand close to ancient pteriaceans, the umbones of close to the middle. Near this genus of only a few stands Plicatula, in which a pair of strong teeth developed, as also in the fossil genus Dimyodon. The identical filaments, as also in Amussiinae, which in gills still- have consist of most cases have thin, inequivalve shells, sometimes with dissimilar structure of the two valves, Propeamussium with a deep notch in the right valve for the byssus, notch being reduced in Amussium and Adamussium. This group lives on the substratum and is not able to swim as some Pectininae do; mantle in this margin eyes are rarely present hermaphroditic. in small numbers. Amussium species are The Pectininae have undergone a considerably higher development through the stronger formation of eyes at the mantle margins and the associated high development of the nervous system, through the ability of some species to swim by the opening and closing of the valves, and through the higher differentiation of the gills. 1642 Spondylus differs mainly by the hinge teeth, which are similar to those of Plicatula but are probably not homologous. It the is latter, ability to probable that limids are related to the Pectininae, because, like they possess pleated swim, but it gill lamellae and in part have retained the appears possible that they have acquired these They characters independently. differ from the Pectininae by the always- absence of similar eyes, the unique rotation of the foot and the approach of the cerebral and visceral ganglia to one another. The Mantellum-group is most highly developed. It hardly appears equivalve shell, the doubtful that the anomiids stand close to Propeamussium, but they have developed uniquely because of the strong asymmetry; the calcified byssus is overgrown by the right shell valve, but in in the shell closed. and the hole Most remarkable is some groups it is lost the fact that the heart without closed pericardium projects into the mantle cavity. Like the kidneys, the gonads are highly asymmetrical, the right one being largely forced into the mantle; this it would be wrong to conclude that because circumstance there exists a relationship with mytilids. one can assume Of that they stand closest to the pteriaceans; as a result the cementation of the left valve to the substratum, the foot has reduced; the A gill shell. differ The marine of become lamellae are pleated as in Pteria. separate developmental series which already of the ostreids is represented from others by the by the schizodonts characteristic structure of the trigoniids have a recognizable relationship with arcids: both adductor muscles are well developed, the mantle completely open, the gills each formed of a rachis and identical filaments fused with one another only gland is at the margin; the kidneys are sack-shaped. rudimentary, the foot is large, The byssus Various suited for burrowing. opinions have been expressed about the hinge of trigoniids; recently it has been regarded similar to the heterodont condition: the right valve has the central tooth, and the posterior tooth represents a union of a 1114 a lateral tooth; the posterior part of the large left main tooth main and is divided by an indentation on the underside. There is also some debate about the relationship between trigoniaceans and unionaceans, though generally such a relationship is admitted. The similar shell structure supports this view, and paleontologists especially emphasized the similarity of arrangement of the hinge teeth; but in this respect sight of the significant modifications that the hinge unionaceans underwent, where it in should not be the series lost of the can not only disappear completely but can also be replaced by altogether different teeth, the genus Iridina even simulating a taxodont hinge (cf. Fig. 810). The mantle margins can fuse with one another and with the gills, the latter having formed perforated lamellae from partially fused filaments; the gills have undergone more 1643 extensive modifications or less unique, but according to trigoniids; the adaptation on fishes is as Odhner brood chambers. The kidneys are found the most similar ones are of most of the larvae to a parasitic also very characteristic. Accordingly, mode of one may assume the unionaceans represent a separate branch of the stem, which recent bivalves stands closest to trigoniids freshwater has enjoyed a rich development. and The after in life that among transition into oyster-like aertheriids, with reduced foot, are the most modified. If one can be able will to relate the hinge assume probably non-nacreous forms. main left teeth of trigoniids of heterodonts, one to that by extinct a relationship with the latter, bridged Among the true heterodonts, in which the do not have the characteristic form as in trigoniids, the marine families Astartidae, Crassatellidae and Carditidae are considered most primitive. Besides the normal main the teeth, lateral teeth are occasionally more or less distinctly developed, but are in most cases The mantle lacking. is in most cases open except for the separated excurrent opening; the gills are as a rule smooth and not fused with the visceral sack and mantle; a byssus is the kidneys are sack-shaped, lost; sometimes well developed, sometimes interconnected, with short proximal limb; not seldom brood care takes place. Pelseneer derives the gaimardiids from carditids, umbones with which they agree in the anterior position of the such a relationship seems rather doubtful; they nevertheless perhaps stand closer to the cyamiids. In below some it is families, in addition to the excurrent opening, an also separated opening from the anterior opening for the incoming current and both posterior openings can be extended into short tubes. In Sphaeriacea, the hinge of the corbiculids shows the freshwater, stirps well-developed teeth, whereas those in sphaeriids are often weakly developed; is lateral teeth are as a rule present. The foot has no byssus and used for creeping. The kidneys of corbiculids differ from the normal condition only by the arch-shaped curvature of the two limbs, whereas in sphaeriids a characteristic convoluted form has developed from the simple loop as a result of several bends of the two limbs. Different opinions have been expressed about the relationship of the stirps while Neumayr and Douville derive it from Cyprina, Odhner assumes that first the genus Corbicula developed from the extinct genus Myophoriopsis, which leads him 1115 to conclude "a common phylogenetic origin of the unionids and cyrenids from 7Wgom'a-like ancestors." At all events one can assume that the small sphaeriids are less primitive than the larger corbiculids. Opinions differ as to whether the lateral teeth in heterodonts are to be considered as primitive or as secondary, and hence opinions also 1644 of some families, for even the body differ as to the interrelationships often provides indication for this. In the family Kellyellidae the little animals are not only of very different size but the mantle is also sometimes completely open, sometimes provided with distinct siphons, and presumably more detailed knowledge would reveal other differences. To may be group of deep-sea inhabitants the isocardiids this related. Pelseneer wants to derive them from cyprinids, from which they differ form of the main in the a consequence of their The teeth. libitinids, life in cavities more or less elongated as are also placed near the cyprinids. small, mainly Antarctic cyamiids with internal ligament appear to The be related here. Completely uncertain appears the systematic position of Dreissenidae, which are widely distributed earlier included in mytilids freshwater; in because of the similarity of the structure of the kidneys they they were shells; in the show some resemblance with gaimardiids, but a closer relationship with them seems doubtful. is It possible that, as assumed relationship between stirps common can only be traced back to close to the astartids. primitive, having 2 by Pelseneer, there exists a closed Lucinacea and Erycinacea but perhaps the two Of the main ancestors, which perhaps stood may be Lucinacea, the Ungulininae teeth in each valve, but no the most lateral teeth, and the gills of which on either side consist of 2 lamellae; the long, thin digging foot is unique. In the Thyasirinae the hinge teeth are reduced, a small incurrent opening, such as possessed as in lucinids, strong bulges on by Diplodontinae, either side is not yet present; of the visceral mass have developed. In the family Lucinidae also, the hinge teeth representing the main and lateral teeth may become the upper one can sometimes which however has no is into a distinct siphon main difference from the Ungulinidae lamellae. The development of accessory retractors; the the reduction of the outer gills reduced; of the 2 posterior openings, become extended gill on the inner side of the mantle of Codokia is unique. The Erycinacea are a peculiar group of mostly small animals the mantle of which posteriorly has only an excurrent opening, while the inflow happens through an anterior opening, the ventral margins are more or less fused together leaving an opening for the in most cases large foot. The erycinids possess 2 gill laminae on either side, of which the montacutids have lost the outer one. The mantle margins of the former sometimes bear one each papillae, in front sometimes longer and behind; tentacles, in this group, the Galeommatinae mantle margins in most become broadened and place themselves upon the surface of the it in Chlamydoconcha as well as in Entovalva and Scioberetia, which live commensally on or in holothurians or spatangids. The gonads of montacutids are hermaphroditics. Pelseneer cases shell. Completely covering 1645 wants to derive them directly from lucinids, and the erycinids from ungulinids, but this appears doubtful. The chamids 1116 are to be derived by cementation of one seldom the right valve, for in According right valve. from Cardiacea, and are characterized valve; in shell most cases this is the left, more Odhner, the ones attached by the to which he erected the genus Pseudochama, differ not only the condition of the hinge teeth, but also anatomically, lacking an anterior blind sack on the stomach, whereas it present in is Chama, and the pericardial limbs of the kidneys lying freely on the inner side, while being completely enclosed by the outer sacks in Chama; Pelseneer states species attached by the right valve that show a situs inversus in the compared position of the intestine and the anterior aorta attached by the valve (the investigated species left Based on the nature of the gills, the chamids are placed a suborder Cardiacea and Pelseneer too derives from cardiids. In the is them the ones to undetermined). by Ridewood form of the hinge teeth and the mantle opening, they have some similarity with tridacnids, which however are modified different in like the tridacnids way and have lost the anterior adductor muscle. in a The more primitive cardiids perhaps not yet possessed an incurrent opening separated from the anterior opening and the siphons are elongated only the foot originally will not have had the size which is in Adacna, so apparent in most of the cardiids. The venerids well are placed next to the cyprinids. developed and show lateral which tooth, is little variation left teeth are anterior often rudimentary or absent; a mantle sinus occasionally absent and hence has folds are also The hinge except for the sometimes first indistinct, developed in the family. The is gill sometimes greatly developed. The siphons are originally completely or largely united with one another, in other genera they are the petricolids, more separated, standing close to the venerids are among which Petricolaria is the most divergent. The mactrids are characterized by their ligamental cartilage, which has failed its way behind the main teeth, of which the right central tooth seems to be absent, but it is probably more correct to assume that the angular tooth consists of the central tooth, and the anterior limb of the anterior main tooth, whereas its posterior limb has disappeared as a result of the penetration of the ligamental cartilage; the in most cases cleft left main tooth then corresponds only to the anterior limb, the posterior limb being more or less clearly indicated. Lateral teeth are present. Here again a mantle sinus less is sometimes not yet developed, the siphons are more or united with one another; the sometimes more or gill laminae are sometimes smooth, less strongly folded, the foot without byssus. With the indicated concept of the hinge teeth, their derivation from those of 1646 the cyprinids, corbiculids, etc. would be and would permit less difficult the placement of Rangia in the mactrids, the former having been placed by Fischer a separate family related with corbiculids. If Anatinella in also related with mactrids, then this relationship on common precursors, called Anatinella 17 by which seems to is be based only have no mantle sinus; an animal still Pelseneer, about which he made some statements, was probably incorrectly identified. Even more doubtful is the relationship between mactridae and Cardilia. Based on the gills, Ridewood has placed the mactrids in a suborder Tellinacea, and Pelseneer wanted to derive from them not only the Tellinacea, here combined as a stirps, but also the Adapedont; however the donacids, psammobiids, and tellinids with external ligament cannot have descended from forms with internal ligament, and the semelids have acquired their cartilage independently. Hemidonax, may grouped earlier with the cardiids, has no siphons, the posterior mantle opening being divided only by the terminations of the laminae are distinctly folded; it gills, the foot is short, the gill perhaps most correct to assume a is separate family or subfamily for them, as Fischer has done. The gills of most of the Tellinacea are smooth but in some Donax species, in psammobiids and in Semele, they are more or less strongly folded. The lateral teeth are sometimes weak or absent; the mantle sinus The separated from the ventral mantle line. foot in is often not most cases has no byssus. The psammobiids were in most cases grouped together with the Ridewood has united them with others in a suborder Myacea, which includes the Adapedonta without the Adesmacea. Here again occur smooth as well as folded gills, and it is to be assumed that the solenids; modification has taken place in the individual stirps; thus the rather small Saxicava species have smooth, the large Panopea and Cyrtodaria folded laminae, in gastrochaenids and the folded; among Adesmacea they are not or scarcely the solendids, Novaculininae and the genera Siliqua and Pharus have smooth, the others folded laminae. The ligament external, main sometimes teeth internal, the always without lateral considerably elongated, more often siphons too are variously long. The have stood close direction from the In the teeth. it is sometimes others, Solenacea the shell is roundish or moderately long, the initial to the Tellinacea; the different is hinge margin narrow, sometimes with forms of the Adapedonta may Solenacea have developed in a among which the saxicavids still possess an external ligament and more or less distinct hinge teeth, the aloidids an internal asymmetrical cartilage and a right hinge tooth, while the gastrochaenids have an external ligament and a tooth-less hinge margin, their shell gaping widely in the anterior portion of the underside. 1647 Near them may be placed the pholadids, the shell of which gapes and posteriorly and has completely lost the ligament, while the anterior part of the dorsal margin is reflected outward and the anterior anteriorly adductor muscle is attached to it, which thus acts antagonistically to the posterior muscle, so that the shell can perform rasping movements with the teeth developed on the anterior part, enabling the animal to bore into wood of the other solid bodies. As a protection for the parts not covered by various accessory calcareous plates have developed in the shell pholadids, whereas the teredinids, like Fistulana, produce a calcareous tube which encloses the entire animal, the shell of which covering like The teredinids have developed some anatomical characters, as well a head only the small anteriormost part. most uniquely in this respect and in as in having "pallets" at the ends of the very long siphons. New the Adapedonta stand the Anomalodesmata which as a have no hinge teeth and an internal ligamental cartilage, lithodesma; siphons and mantle sinus are sometimes little still rule often with a developed, the gonads with the exception of the cuspidariids are hermaphroditic. The are variably developed, gills inner laminae are are still in Pandoracea and Clavagellacea the well developed and folded, whereas the outer ones most cases represented each by a in single, upwardly directed lamella; but in verticordiids they are narrow, net-shaped, 1118 less and more or fused with the septum, which becomes perfected in poromyids, whereas the gills are reduced to 2 or 3 small sieves or rows of holes; in cuspidariids the strong septum on either side contains 4 or 5 holes and the are gills completely reduced. The tooth-shaped elevations of the hinge margin sometimes occurring here are probably not homologous with the teeth of heterodonts; the structure and form of the shells are variable, in clavagellids, as in Fistulana, a tube enclosing the animal along with the long siphons has developed, and in Clavagella this tube has fused with one of the shell valves in Brechites with the entire shell, so that it The ancestral can no longer be moved and the adductor muscles disappear. class of the cephalopods has developed independently from the conchiferans and has by far attained the highest stage. Like scaphopods and bivalves, they have retained the original bilateral symmetry, and have not undergone a torting of the visceral sack against the foot as have the snails; accordingly they have paired ctenidia and kidneys, originally also paired gonoducts, although the gonad single. some opisthobranchs, "funnel" by broadening of the Similar to that in transformed into the the foot lateral dibranchs, by fusion of the free margins, the funnel has tube which is open anteriorly and posteriorly and the mantle, and serves as the swimming organ. As is always has become margins; in the become a closed by is largely covered in zeuogobranchs, the 1648 head originally has open eyes, but in dibranchs they are in most cases developed into highly efficient visual organs. One can also assume that the cephalic tentacles and an epipodium were originally present, as in zeugobranchs, and have become transformed into the arms of the cephalopods. The pharynx, with radula and jaw as well as a subradular sense organ, has also been inherited from the ancestral conchiferans, but jaw here a lower also developed, is which together with the upper jaw forms a powerful biting organs resembling a parrot's beak. The radular with projecting, more or less long cutting edges, simple, are plates originally without differentiation. of the buccal ganglia more to that — shows The nervous system little — with exception resemblance to that of zeugobranchs, of bivalves, because an anterior and a posterior ventral cord, corresponding to the pedal and the visceral ganglia, issue from a cord corresponding to the cerebral ganglia overlying the pharynx; but in dibranchs these are united with one another and the innervation centers of the arms have become detached and form special arm ganglia which are connected with the pedal, cerebral and buccal ganglia. The parts are from one another by connectives, so that a sharp delimitation between cerebral and pedal ganglia is not recognizable; originally not separated special pleural ganglia are also absent. The shell zeugobranchs, of the cephalopods is originally external and, as in the internally nacreous, externally colored. Very early it became elongated and chambered internally by numerous septa pierced by a "siphuncle" which- is sometimes wide, sometimes narrow; the it is animal inhabited the last chamber, but in most cases remained in contact with the other chambers by a process lying within the siphuncle. Of the 1119 numerous cephalopods with an external shell, which have lived a very long time ago and were probably very diverse, only the genus Nautilus has survived to the present day, so that only from this form. It we know body hood and the nature of the consists of a very large head with the numerous cirri and a massive body lying in the last chamber, the underside of which anteriorly showing the large bilobed funnel and posteriorly 2 pairs of gills in the mantle cavity. This body form had to be changed when the animals clasped their elongated shell with lobeshaped processes and gradually completely enclosed it, as it is the case in the belemnites. Because of this the body underwent a considerable considerably elongation and the shell turned from an external protective organ to an The internal support. have be visualized to The oldest ancestors of the currently living dibranchs way. in this seem have originated from the same ancestral forms from which the belemnites arose. Because the belemnites had in all probability only one pair of ctenidia, corresponding on the one hand nautilids also to 1649 to those of the zeugobranchs and the primitive bivalves, and on the other it is to be assumed that one hand to those of the decapods and octopods, pair of gills of the nautilids represents a special acquisition. The origin way that of the anterior pair of gills will have to be visualized in such a each ctenidium continued anteriorly from the base of the process bearing the two rows of case in primitive bivalves, and that leaflets, similar to the these anterior portions detached lobe-like from the body; later the rows of lamellae between the two processes became interrupted, so that on each side 2 separated gills arose. As a result of such a division of each ctenidium, the vessels had to divide as well as the excretory glands gill developed on them (pericardial glands land kidneys), so that the anterior pair of kidneys developed in association with the anterior pair of gills. An acquisition of the cephalopods additional body large has entered into connection with the gonad. state is a further some the is more or less which represents a widening of the pericardium and cavity, development compared snails the pericardium has It cannot be doubted that this to that of the other mollusks. In undergone a usual extension (Septaria) and similarly one can assume that cephalopods in it has enlarged somewhat more and has penetrated between the gonad and its effecient ducts. Accordingly, the germ cells must pass the body cavity, but they are immediately taken up by the gonoducts lying opposite to the gonad. These conditions yolk-rich at all events arose as an adaptation to the very large and eggs or to the mass production of sperm and the large spermatophores. The phyletic relationship of nautilids to the dibranchs may thus be so visualized that the former are their external, chambered shell, as well as more primitive because of because of the bilobed funnel, the open eye cups, and probably also because of the form of the nervous system; it may be uncertain what shape of head and arms the initial forms of the dibranch had, and they probably would not have possessed such a cephalic hood as in Nautilus. These elongated and chambered 1120 found to shell. Its initial forms still had an considerable length was gradually be useless and obstructive, and a shortening occurred, which produced various results. ventral retaining side, still In Spirula its distinct the shell curved in towards the chambering and, because of the incurving, had no anterior process; in Sepia assumed the form of a became obliquely placed in a highly characteristic way. Only in these two families is the shell still calcified, in all other decapods which still possess a shell, it is horny, and not chambered; it corresponds to the "proostracum", it dorsal shield, on the underside of which the fine septa whereas, along with the "phragmoconus" the equivalent of the original external shell has completely disappeared. . 1650 While Spirula has most clearly retained the remains of such a calcareous shell, the body shows in part primitive characters like the open eye chamber, and in part special modifications, such as the absence of a radula. It seems uncertain whether Idiosepius is directly related with Spirula because of the similar body form and the two hectocotylized arms, in spite of the absence of a shell. The sepiadariids and ventral The sepiolids also have no or only rudimentary shells. loliginids have resembling those of Sepia, but a horny "gladius" as in the eyes Architeuthacea. The represent a separate developmental latter from the Sepiacea differing the Loliginacea — with the exception of Spirula by the open eye chamber; in series, — and from addition they lost the accessory nidamental glands. They advanced phyletically in different ways, so that their interrelationships are difficult to ascertain. The following may be a buccal membrane with regarded as primitive characters: an elongated body, and paired gonoducts; although eight lobes, these are not found together in one group that could be considered as a little modified initial form. Some are probably to be regarded as body and divergent, such as Histioteuthis (Fig. 877) with short the large velum, but especially the cranchiids with their greatly enlarged body and mantle cavity and the fusion of the mantle to the funnel, and among the Bathothauma The is the most peculiar (Fig. 882). phyletic relationships of the octopods with the decapods are not very clear; the phylogenesis of the former has been discussed in detail by Robson. He with 10 tentacles, he could assume that they stand close to decapods arms, of which the 4th pair whereas the 2nd pair would correspond process of orders felt identical still some vampyroteuthids. At all later developed into to the thread-shaped events such ancestors of both possessed separate kidneys and paired oviducts, their arms were beset with one row of suckers. On the whole, the most primitive octopods are the vampyroteuthids with well-developed radula, the plates of which are simply pointed, with a which in Vampyrotheuthis is distinct internal shell, the comparable to the gladius form of of Architeuthacea, with fins on the widely open mantle, with a funnel valve, and perhaps also other characters, such as the moderately long of small suckers; on the other hand the are to cirri arms with one row and the broad velar membrane be considered as special acquisitions. Near them stand the Cirroteuthacea, primarily the stauroteuthids, the mantle of which has a narrowed opening and radula of which is in Chunioteuthis fuses with the funnel, and the reduced. Cirrothauma is peculiarly modified, with a completely gelatinous body, attached to which are a pair of large 121 fins, and the eyes are rudimentary, without lens and ganglion; of the suckers, only the 6 innermost ones of each arm are normally developed, the others 1651 are depression, spindle-shaped, without distal contain a whitish body consisting of a spherical in the proximal cell mass and a portion cartilage- and has a certain similarity with light organs. Opisthoteuthis is highly modified in a different way, in which the shortening of the long axis of the body (distance of the mouth from the posterior end) has like shell, reached the highest degree, so that the posterior of the body forms only a flat hump, attached to which are a pair of small fins; the mantle opening narrowly encloses the funnel; the suckers are normally developed, sometimes and crowded together. large fairly Another developmental series of the octopods, which again divides into 3 large branches, is represented by the Incirrata, in bears no fins and contains no or a very rudimentary less long arms bear or 2 rows of suckers, but no 1 no broad velar membrane. Of arms; soft more or most cases show a their rather body without distinct jaws can be considered as primitive, but there cartilage and the no doubt that the strongly soft a special acquisition. in open eye chamber and seems doubtful whether the it and cirri the 3 branches, the bolitaenids primitive condition because of their short which the mantle shell; the is broadened intermediate plates of the radula are The amphitretids more modified with long arms are connected by a broad membrane, with the eyes approaching each other on the dorsal side, and with the funnel fused to the martle; here too may be placed the vitreledonellids, the arms of which are long and connected by a membrane and their radula having undergone a certain reduction presumably associated with the small formation in Octopodacea, this stirps is in which at little size of the viscera. The hectocotylus developed and differs from that of the the end of one of the 3rd arms a large spoon-shaped structure (cf. Fig. 890) is more or less developed. The arms of the octopodids sometimes reach considerable length and strength, the sucker rows occasionally appearing doubled because of their The radular and mainly the median plates have relatively broad bases being compressed. ones have often small accessory cusps, the inner intermediate plate small. The ink sack is is sometimes reduced (Bathypolypodinae). Because of the difference between the sexes and the detaching, greatly modified hectocotylus, the developement, and Argonautacea reach the highest stage of peculiar at the end of this series stands Argonauta, in which the females possess the unique spiral shell, which, as a product of the lobe-shaped broadened dorsal arms, has perhaps developed because such arms initially shell for only received the eggs and only gradually secreted a firm them. The similarity of the radular plates, especially of Ocythoe, with that of some decapods, can hardly be considered of relationship. as an indication 1652 Thus the octopods are because of several different traits such as the fusion of the mantle margin to the body, which at times underwent the most extreme shortening, the rudimentary or completely lost shell, the highly organized eyes, the short gills, and the reduction of the pericardium, the most highly and uniquely developed mollusks. 1 Paleontology and Phylogeny 122 This is not the place to go into the details of the relationship between paleontology and systematics of Recent mollusks, that being a subject for paleontologists, but certain aspects of significance for the phylogeny and the system will be highlighted. The rare finds of fossil loricates agree well with the conception of the phyletic development of the class. in their own The most order Helminthochitonida which primitive forms are put still lacked apophyses; hence they do not yet seem to have developed an articulamentum nor perhaps a differentiation of shell layers, but the perinoturn surrounding the elongated body was already beset with spines. The shells found in the Palaeozoic belong to Lepidopleurida because of the absent insertion margins, and only from the Liassic are some known with incised insertion margins. the genus Protochiton from the Australian Oligocene, which the terminal valves still have no insertion plate, whereas the apophyses are large and extend posteriorly on the sides. Ashby believes Ashby described in this form into a phyletic relationship to the acanthochitones which he placed as a separate phylum in contrast to the remaining chitonids. This, however, cannot be accepted, because, apart from the he can bring fact that this Protochiton is far too young, there is no reason to exclude from the lepidopleurids, for the shape of the apophyses is quite similar to those in Hanleya, as also the surface sculpture, and the absence of an it anterior insertion margin is the only important difference. In other respects, the fossil finds can hardly be taken into consideration for the classification of the interrelationships of chitonids. ancient times a concluded from shortening and broadening took place, this more primitive than that the among Recent forms shorter ones; it Even if in cannot be the elongated ones are but rather such animals as Cryptoplax, Stenochiton and Schizochiton are undoubtedly individually adapted forms. The more or less distinct sculpture small phyletic importance, because Much it is also probably of occurs in various groups. better preserved are the shells of marine snails from as early Cambrian period and these can be taken into consideration for the recognition of the phylogeny, but at the same time it should be born in as the 1653 mind so forms can appear that certain shell characteristic little that in various groups and some one can say nothing definite about are their systematic position without a knowledge of the animals; for this reason some Such a system uncertainties persist in the paleontological system. has been worked out by Cossmann, and a brief review of it may serve to highlight some deficiencies in comparison to a system of the Recent snails. The fact that pleurotomariids have been preserved since the Cambrian to allow the conclusion that they seems have lived in protected places or in quiet waters, whereas the haliotids, which stand very close to them have adapted to in their organization, much more only from were easily ground up by the 1123 life on the seashore and are known recent times, partly perhaps because the shells surf. The species allocated by Cossmann to Subemarginula and Scutum from the Eocene of Paris seem to include members of cocculinids. The family Trochidae is divided into a number of subfamilies; Trochinae, Polyodontinae, Monodontinae, Umboniinae, Gibbulinae, Margaritinae and Conulinae. The last of these corresponds mainly to Calliostomatinae, but Jujubinus and Strigosella belong to Cantharidus, Lischkia (= Lischkeia) and Euchelus to Margaritinae, which are essentially acceptable except Minolta and Conotrochus; Monilea Chrysostoma does not belong very different. The stirps — there. called to is be placed Umboniinae, but in The remaining subfamilies are not cenacle by Cossmann Astylacea, — cannot be accepted; they are trochaceans with ear- or cup-shaped which part (Stomatella) in whereas Phaneta presumably does not belong here. Eucyclinae is placed by are nacreous, for shells shell, stand near Euchelus, in part near Gibbula, Cossmann under the littorinids, A subfamily although the which reason the group perhaps properly was placed by Fischer in the trochaceans, Littorinopsis which does not have a nacreous shell has evidently to be excluded. Cyclonematidae and Paraturbindiae also rather than to the littorinaceans, at tightly coiled, externally like that events this Cossmann in to the trochaceans is supported by the cone-shaped operculum of Trochonema, which, of the Horiostomatidae, compares best with Near the Liotidae, placed, all The Trochonematidae, may belong that of Leptothyra. which Lippistes and Mecoliotia were erroneously puts the extinct families Peristomatidae, Ataphridae and Colloniidae, but also the Cyclostrematidae with the subfamilies Cyclostrematinae and Tinostomatinae, whose genera were taken mostly from the Skeneinae and the Adeorbidae; here. The turbinids this last group and phasinellids are essentially Littorinacea, in addition to Littorinidae among which Phasianema and is also included correct. Near the and Lacunidae stand the Fossaridae, Jsapis which actually are pyramidellids 1654 are placed. Of the rissoids, believes that the rissoas derive Cossmann from Palaeozoic littorinaceans, the rissoinas from entirely different forms, which however is unlikely in view of the great similarity of the dentitions; among the rissoas, genera are named which belong to the Barleeinae, whereas Barleeia stands near the litiopids, which are also Fenella Rissoacea; regarded as and Scaliola are also no rissoids. Micromelania and Baicalia are called hydrobiids. The cenacle Euomphalacea contains a very peculiar assortment of differing groups; next to the Euomphalidae, among which the Recent genus Pseudomalaxis is named, and the Solariidae, stand the among the pleurotomariids, as Raphistomidae, which Fischer counted well as the xenophorids, the extinct Cirridae, and the delphinulids. believes that the loxonematids, even though they do not Cossmann possess a slit, from murchisoniids, which belong are to be derived pleurotomariids because of the slit in the apertural margin. He to the recognizes Loxonematacea, in which, aside from the extinct families Loxonomatidae, Coelostylinidae, Spirostylinidae, Pseudomelaniidae, a cenacle Subulitidae, he also wants to place the Mathildidae, Scalidae, Turritellidae, Vermetidae and Caecidae. That the genus Vanesia A. Adams, 1861, from is related to pseudomelaniids appears to be just the littoral of Manchuria as uncertain as the relationship of Abyssochrysos. 1124 the common loxonematids as the Koken wanted to view root not only of siphonostomous taenioglossans, the rhachi- and toxoglossans, but also of pyramidellids and opisthobranchs, but this is of not much use for our zoological system, because the organization of these forms is completely unknown. Probably they will essentially have belonged to the Cerithiacea, and perhaps some of the Recent groups of this stirps are descended from them. In the cenacle Cerithiacea the following families are distinguished: according to Fischer perhaps related to Terebralia, but Eustomidae — according to Cossmann intermediate (?) between the Alatacea (= Strombacea) and Cerithiacea; Brachytremidae, which hardly belong here; Procerithidae, without a siphon, with the subfamilies Procerithinae, Paracerithinae and Metacerithinae, all of which are extinct; in addition the Cerithidae with the subfamilies Cerithinae, Potamidinae and Bittiinae; Cerithiopsidae, Triforidae, Diastomidae with an apertural sinus, but without canal, which perhaps correspond to the Finellidae; also the Trichotropididae, of which he states that in the shell form they show some affinities with purpurinids, which are also placed here; and finally the Planaxidae and Modulidae. Strangely, the naticid genus Acrybia is placed in the Janthinids; with (= Couthouyia) and Macromphalina (= Megalomphalus), but not Fossarus. Among the the vanikoroids are named Micreschara 1655 Alatacea, the struthiolariids are declared as reduced aporrhaids; besides the strombids, the fossil columbellinids are also placed with this stirps. It to cannot be accepted that the strombid genus Terebellum Simnia through the extinct Diameza. Cossmann Euspiridae from the naticids and maintains that them to place together, because the latter are whereas the former had a capuloid it connected is separates a family would be a great error derived from Loxonematacea, origin. Among Euspiridae he the names the Recent genus Cernina = Globularia, the anatomy of which is Amaura. However, his view not known, and closer relationship between naticids because a accepted, can hardly be He also seems to assume closer relationships not exist. and capulids does The naticopsids and neritopsids. Cypraeacea form a with of the naticids also the pyramidellid genus cenacle Involvacea, and to the Doliacea corresponds a cenacle Tritonacea. The Muricacea are divided into Muricidae with the subfamilies Muricinae, Ocenebrinae, Trophoninae, Typhinae and Rapaninae, into Purpuridae and Coralliophilidae; the Buccinacea into Nassidae with the subfamilies Nassinae, Dorsanine and Truncariinae, Buccinidae with the subfamilies Buccininae, Cominellinae, Photinae, Pisaniinae and | Anochetinae, into Chrysodomidae, Pyramimitridae (including Nassarina), and Strepturidae (including Melapium); also the Fusacea into the families Fusidae with the subfamilies Fusinae, t Streptochetinae, Fasciolariinae and Ptychatractinae, and Turbinellidae with the subfamilies Turbinellinae, Tudiculinae, Fulgurinae and Melongeninae. families The cenacle Plicacea comprises the Mitridae with the subfamilies Orthomitrinae, Plesiomitrinae, Semimitrinae, Pseudomitrinae and Cylindromitrinae, Volutidae with the subfamilies f Pholidotominae, Loxoplocinae, Volutinae, Cymbinae, Zidoninae and Homoeplocinae, Cancellariidae with the subfamilies Cancellinae, Trigonostominae and Admetinae, Olividae with Olivinae and Ancillinae, and finally Harpidae and Marginellidae. The named and partly they do not subfamilies are probably partly superfluous, correspond to the actual interrelationships. 1 125 Cossmann erected a separate suborder Entomotaeniata for a group of of the Mesozoic, with the families Tubiferidae, fossil snails Nerineidae; he assumes that this group or the pyramidellids; some have greater similarity with Of the (Itieria) is Itieriidae and be placed near the tectibranchs to resemble these somewhat, others cerithiids. Cambrian forms, the bellerophontids were probably not at all gastropods, and for this reason they are placed in a separate class, the Amphigastropoda, the animals of which were and probably led a swimming mode of life still bilaterally symmetrical like that Their symmetrically inrolled shell as a rule had a band similar to that in zeugobranch snails. It is slit of the nautilids. with an adjacent altogether impossible to 1656 regard these, especially Porcellia, as ancestral heteropods (Koken). matter of fact it As a appears highly doubtful whether Cambrian snails are related to recent one, with the exception of the pleurotomariids, but even in this family the shell has like the trochids, the forms so diverse that it may be assumed that, animals would have shown considerable differences; of the developmental series one then led to the haliotids, another to the scissurellids, still another series to fissurellids, to trochids, as well as to extinct groups like the euomphalids. with solariids. In the same It way one is already lived in the Cambrian, capulids impossible to relate the latter not be able to assume that will and a direct descent of the loxonematids from Murchisonia or of the xenophorids from trochaceans likewise excluded. One will have to assume that only from one group of archaeogastropods, of which only the trochaceans can be considered, the ancestral form of the mesogastropods developed, to which among the marine families the lacunids probably stand closest; and likewise that only from one group of mesogastropods (Doliacea) the stenoglossans derived, and that from still another, which was most closely related with pyramidellids, descended the ancestral form of the opisthobranchs. Because of the great uncertainty about the is of Palaeozoic snails affinities to recent ones, the first appearance of certain groups often remains highly doubtful, such as the occurrence true docoglossans of and pteropods in the Cambrian, and of scalids and pyramidellids in the Silurian. But up to the Carboniferous, the phyletic development had ma'de significant progress, and it is very noteworthy during this period not only actaeonids but even pulmonates had that already made their appearance: Zonites (Conulus) priscus Carpenter, which probably was closely related to Pyramidula, Anthracopupa ohioensis Whitfield, Maturipupa vermilionensis (Bradley) and (Dawson); seems inconceivable it that such Dendropupa vetusta forms already lived in the Devonian, especially because otherwise the ellobiids are known only since the Jurassic, just as most groups of the snails more highly developed have originated during the Mesozoic. known from the older Cambrian, and may be concluded that the bivalve form developed only Fossil bivalve shells are not from this fact it during the course of this period, and hence is younger than the snail form. The bivalves occurring in the uppermost Cambrian or lowermost Silurian belong to the taxodonts and modiolopsids. 126 Salter can be included in the nuculaceans arcaceans; it is remarkable that the latter, The genus Ctenodonta and Glyptarca Hicks with its in the long posterior hinge teeth parallel to the margin, can be considered as a secondarily modified arcid form, if it is assumed that species with normal teeth have preceded — 1657 them, and were not preserved' because they were firmly attached to stones by their byssus and were destroyed by the surf. Glyptarca has pointed umbones approaching the anterior end and only few anterior hinge teeth; in Modiolopsis Hall the umbones are terminal and the hinge margin has 1-4 short, oblique, and 1 or 2 long teeth, Cyrtodonta Billings has nearly terminal umbones and 2-8 small and a few very oblique posterior hinge teeth; the latter group can probably the arcids or at least be derived from it, but still affinity to its be allocated to gaimardiaceans and dreissenaceans seems more than doubtful. Judging by the shape of the area, the cardiolids also belong /to arcaceans, but without relationship with cardiids. The hinge in the ancestors of the anisomyarians cases edentate included in — like Philobrya, Ambonychia Hall retain the may median position in the Aviculopecten pectinaceans be considered a transitional form more or pteriaceans they have shifted — most is in perhaps also to be and the umbones lie Posidonomya Bronn; they Glyptarca but allied to arcaceans, close to the center of the hinge margin as in is — whereas Mac Coy mytilaceans and in less far forward, as in Pterinaea Goldfuss. The Silurian genus Lyrodesma Conrad, with 5—9 transversely grooved teeth radiating out from the umbones, form of the The trigoniids. latter at considered as the is initial events acquired the unique all structure of the shell, whereas the cardiniids, to which belongs the genus Trigonodus Sandberger mentioned by Odhner, do not possess a nacreous shell, because of which they are allied to the Carditacea. Anodontopsis Mac Coy stirps Astartacea and has been recently placed with the Cyprinacea. The Silurian grammysids and praecardiids are thin-shelled bivalves without hinge teeth which have been called "desmodonts," but a with relationship direct excluded. It is emphasized found predominantly to the seashore pholadomyids that the in deposits known will probably have to be Silurian bivalves have been of deeper seas, those from parts close were thus probably largely destroyed, whereas such forms appear ever more richly in the Devonian and Carboniferous. Most of the extant groups developed in the Mesozoic in place of groups; among them some Paleozoic the anisomyarians gradually decline in comparison with the eulamellibranchs which have also invaded freshwater. As far as the cephalopods are concerned that the oldest forms, among which Spath it is now generally assumed calls the endoceratids not the ancestors of orthoceratids but also of the nautiloids and the had elongated second pair of shells. gills, This latter series whereas the first alone seems to have acquired a series, the Triassic are placed, possessed only the fossil decapods into: 1. only ammonoids two near which belemnoids of ctenidia. Naef divided the Belemnoidea, with the families Aulacoceratidae, Phragmoteuthidae, Belemnitidae. Belemnoteuthidae, Xiphoteuthidae and 1658 Vasseuriidaae; Teuthoidea 2. Geoteuthidae, Belopeltidae, — Prototeuthoidea, a) with the families Leptoteuthidae and Plesioteuthidae, — b) Mesoteuthoidea, with the families Trachyteuthidae, Beloteuthidae, Palaeololiginidae and Kelaenidae, c) Metateuthoidea, with the Recent Myopsida (= Loliginacea) and Oegopsida (= Architeuthacea); 3. Sepioidea, — 1127 Belemnosidae, Belopteridae, Belosepiellidae, with the families Spirulirostrinidae Spirulirostridae, Idiosepiidae Among and the Recent Sepiidae, Spirulidae, and Sepiolidae. octopods, Palaeoctopus fossil Woodward is important, for which Naef erected a subroder Palaeoctopoda; the impression in the upper Cretaceous shows an egg-shaped body with triangular fins, containing a shell rudiment and an ink sack and a narrower head with variously long arms, each bearing one membrane seem row of suckers; cirri and a velar be absent. to Geographical Distribution of the Mollusks Because of the great age of the lepidopleurids and distribution in development seas all is Lepidopleurus it is understandable that the place their present of their first not recognizable. The extant species of the genus in south the [L. (Haddon)] reach the kerguelensis Metantarctic, but not the Holantarctic; in the north [L. asellus (Chemnitz) and cancellatus (Sowerby)] they reach Greenland, the former also Spitzbergen but without being confined to the cold sea; others have been found at considerable depths; L. belknapi Dall 1800 m, opacus Dall 3650 m, simplex Nierstrasz and setiger Nierstrasz 1300 m. planus Nierstrasz 2050 m, giganteus Nierstrasz 2800 m and benthus Haddon 4200 m; the are situated in the localities however live in divergent Pacific and Indian oceans. Most species shallow depths. The subgroups, proposed for somewhat species, most cases have in little phyletic Parachiton, the typical species of which lives near been found by Sulc in the New significance; Guinea, has also Miocene of Central Europe. The sole relative, and the few Oldroydia species from California has no close Hanleya species as well as the Australian Protochiton (cf. p. 1651) no connections to higher loricates. But, may be assumed for have on the contrary, such a connection Hemiarthrum, which extends from the Kerguelen to the Magellanic region. Evidently, the most closely related genus Tonicella is [T. restricted to the northern hemisphere, with 2 circumpolar species rubra (Linne) and marmorea (Fabricius)], although the in the south to the similar, (Dall & whose southernmost species canariensis Simpson) latter extends Gulf of Mexico. The distribution of Lepidochiton live (Thiele) is and liozonis near the Canaries and the West Indies; it is 1659 doubtful whether solidior (Carpenter) from the Philippines belongs here. The only known Mopaliella species from Peru differs from Lepidochiton only by groups of rather large needles on the perinotum; the closely Middendorffia related is restricted Ocean (Canaries, Azores) and the to warm of the Atlantic parts hand the Mediterranean Sea, on the other Nuttallina lives near California and Japan. Of considerable interest are Notochiton and Nuttalochiton, the former of which lives in the Holantarctic, the latter near Tierra del Fuego on the one hand of the paired gonads, found only and on the other for the multiple connections in these cases, groups of loricates. The most primitive group of Callochitoninae: Icoplax, the median shell pieces on either side possess only one incision and the radulae of which have a cutting edge on the with other lateral lives plate, in the Antarctic Ocean, Trachyradsia near South New Zealand and the Kermadek Africa and Tasmania, Eudoxochiton near few species have extended Islands, only [laevis into the tropics and only one (Montagu)] into the northern Atlantic. But of the mopaliids only the genus Plaxiphora and 2 Mopalia species [M. australis Suter from the Snares Islands and M. (Semimopalia) grisea Dall from Cape Horn] are known from Pacific southern seas, most of them living in the northern the Ocean, Symmetrogephyrus (= Amicula) having arrived Ocean. The situation in the Acanthochitoninae; few species of the genera Cryptoconchus and Acanthochiton live near New Arctic Zealand and in the is similar in the Magellanic region, others have spread more or less Craspedochiton too northward, but are lacking in the cold seas; far inhabits the warm seas, especially the Indian Ocean; the large Cryptochiton extends in the Pacific to the Aleutians and Alaska. Choneplax, which is from the Cryptoplax species living but the frequently occurring C. at less some wide live in the is Cryptoplacinae, widely separated present in the Indo-Pacific Ocean, Winlandi Sulc in the European Miocene proves that such species earlier lived also species, Of the indigenous to the West Indies, at other places. Of Chaetopleura Magellanic region, partly however distribution, C. fulva (Wood) in more or for instance also occurring near Portugal; other species live partly in southern areas, near South Africa and Australia, partly in the tropics; only C. livida (Middendorff) is stated to be found near Sitka. The very species-rich subfamily Ischnochitoninae is also absent the from the Holantarctic; few Ischnochiton species living in Magellanic and Aucklandic region, the subgenus Stenoplax in warm part of America, only few species /. (St.) alatus (Sowerby) and lindholmi (Schrenck) near eastern Asia and /. (St.) madagassicus Thiele near Madagascar. The subgenus Ischnochiton, with predominantly several species, inhabits the Australian widely distributed, only one species coasts, [/. rissoi but is also otherwise (Payraudeau)] being 1660 indigenous to the Mediterranean Sea. The species of the subgenus Chondropleura are scattered in the southern seas; /. (C.) exaratus G. O. Sars being found in the Magellanic region, but has spread to Norway without being found on the east coast of South America, occurring however near North America. The only Arctic species, extending southward England and California, is subgenera of Lorica, Lorica to (Stenosemus) albus (Linne). s. haurakiensis Mestayer) also near Of the and Loricella as well as some one species species are represented near Australia, Callistochiton (L. /. s. New Zealand; the majority of the are distributed on both shores of the of the genus Chiton, some species two subgenera Of the species mainly of Lepidozona northern Pacific. of the subgenus Chiton, which to America, occur near New is otherwise almost completely restricted Zealand and Tasmania to eastern Australia: C. (Poeciloplax) glaucus Gray, C. (Sypharochiton) pellisserpentis and Gaimard, sinclairi Gray, & May Iredale torri Suter, mayi and septentriones Ashby; only C Quoy maugeanus (Pilsbry), connectens Thiele, is said to be found near West Africa, still belongs to Chiton s. s. The subgenus Rhyssoplax has spread over all coasts of the Old World but is most abundant in the Indo-Australian region, the Mediterranean Sea which containing only 3 species: C olivaceus Spengler rubicundus O.G. Costa, and phaseolinus Monterosato, none having reached England. Most species of Acanthopleurinae live in the southern hemisphere; Squamopleura and Acanthopleura mostly near Australia; only one species near Japan, and one 1129 West in the Indies; Enoplochiton and Mesotomura on the west coast of Sourth America. The Tonicia species inhabit the same coasts, but in considerably greater extent, because they reach Patagonia and the Auckland and Campbell Islands in the north. in the south, Philippines, Moluccas, Maldives and eastern seems and California and Japan known from the Australia. On the whole, it The peculiar genus Schizochiton is from south to on the European coasts in that the distribution of loricates has taken place north; very striking is the paucity of species comparison with Australia, but also with California. The few Pleurotomaria which have survived species, to the present, have been found in the West Indies, near Japan, and near the Moluccas, at depths of ca. indicates 130-400 m; the considerable size of most species favorable conditions for existence, they appear to mainly on sponges. The Moluccan species P. rumphii Schepman similar to the West Indian P. adansoniana Crosse & P. subsist is Fischer. most The these small animals distribution of the scissurellids inhabit all seas, amoena Thiele) the Holantarctic, a few the Kerguelena and the Patagonian a is quite different; few species (Scissurella euglypta Pelseneer and region, others have extended more or less far northward, one {S. crispata 1661 Fleming) into the Arctic Ocean, but without being confined to genus Schismope Snares the is less whereas Islands, it The has reached northward only to Japan; Incisura has been found only near The it. widely distributed, 3 species of which live near New Zealand and the Snares Islands. haliotids are shore dwellers; according to Pilsbry, Australia and the neighboring parts of the earth are to be considered as the center of number of species and diversity of They have probably reached the west coast of North America (Alaska— California) by way of eastern Asia; south of California distribution, because here the largest form noticeable. is only one species none from the The is known and one east coast as fissurellids (H. tuberculata Linne) from Europe, of America. a whole inhabit especially the warmer seas, Zeidora mostly the Pacific Ocean, one species the West Indies, partly at considerable depth; Emarginula, with 2 species of the subgenus Tugalia, extends into the Magellanic region, E. striatula Quoy & Gaimard to the Snares and Bounty Islands, 2 species occur near Norway. Scutus inhabits the coasts of Australia, New Zealand Africa in the west. Hemitonia in the south, Japan in the north, and and Clypidina appear to be originally indigenous in the Indian Ocean, from where they have spread eastward into the Pacific, and — probably westward — West to the Indies. The few species of the genus Rimula live in most cases in the western Pacific Ocean, one near Mazatlan and one in the Ocean, but Cranopsis occurs predominantly lives mostly in West Indies to the Atlantic in the Atlantic; Puncturella cold or deep seas, P. noachina (Linne) appears to live not only in the Arctic Ocean but also in the Magellanic region and near Kerguelen, P. spirigera Thiele is holantarctic. The species of the genus Diodora are distributed over the warm and temperate restricted to America, except Cosmetalepas, which is seas. Lucapina is perhaps not closely related. Of the sole species of the subgenera Fissurellidea and Pupillaea, one inhabits Patagonia, the other South Africa. Fissurella s. s. lives on the west coast of South America washed by the cold current, on the other hand Cremides is distributed over the warmer seas; Amblychilepas is known from Africa and Australia, Macroschisma from Australia to Japan and Suez. 11 30 Scutelllastra, the most primitive group of the patellids, seems to have originated from the Indian Ocean, because the species live mainly on the coasts of Australia and South Africa, only the larage P. (S.) mexicana Broderip California). & Sowerby having reached America (from Peru The coast of southeastern Africa harbors the to greatest abundance of forms of various sections, on the other hand, the subgenus Patella is confined to the Atlantic coasts. Nacella inhabits the southern cold seas from Kerguelen to Chile, but Cellana the warm parts of the 1662 Indian and Pacific oceans, only few species have reached and neighboring islands, Atlantic Ocean, of the Acmaeids, Lottia inhabits only the coast, New Zealand one each Juan Fernandez and Chile, none the on the other hand Acmaea with several species is American west widely distributed, but more predominantly in the Pacific Ocean; A. rubella (Fabricius), and testudinalis (Muller) have advanced into the Arctic and also into the northern Atlantic, and similarly A. virginea (Muller). Only few species of Pectinodonta are known from the deep sea of the West Indies and the Moluccas. The few species of the lepetids live partly in cold seas (Lepeta), partly in the deep sea (Propilidium). Among the trochids the genus Margarites lives in the Arctic as well as the Antarctic Ocean, in the latter mainly the subgenera Margarella and Submargarita, but some species of Margarites s. reported; it is uncertain whether the genus also occurs s. in have also been warm seas. The related genera inhabit the warmer parts of the Indian and Pacific oceans, only Solariella extending with 3 species into the Arctic Ocean and being also represented in the Atlantic; Guttula, as Calliostoma well is as Calliotropis, Basilissa, Seguenzia Gaza have been found a genus living in south by a few species & by C. occidentale (Mighels all and considerable depths. seas and depths, represented in the Magellanic and in the at Adams) New Zealand region, and in the boreal Atlantic. Gibbula has a wide distribution but only on the coasts of the Old World, similarly Cantharidus, Clanculus and Trochus, as also the Umboniinae, except Halistylus, the Stomatiinae — except for one species, [Stomatia coccinea — and the Angariinae; Monodonta also Adams)] in the West Indies has only a few species on the west coast of South America, but Tegula inhabits mainly the American coasts, with few species also Japan, the (A. single Cittarium species inhabits the The few known West Indies and Norrisia California. species of the Skeneinae are scattered across seas, all represented in the Arctic Ocean by the group Lissopira, in the Antarctic Ocean by Cirsonella; this group and that of the Cyclostrematidae are still insufficiently known. Of the Liotiinae, Liotia inhabits the warm seas, Cynisca South Africa, Leptothyra with one species (L. innocens Thiele) reaches the holantarctic; on the other hand Molleria the Arctic Ocean. Bothropoma is known only from the Red Sea and from western Australia; warm seas, mainly in the Pacific and Indian the Turbininae live in the oceans, only one species Mediterranean Sea. Of [Astraea {Bolma) rugosa (Linne)] in the the Phasianellinae, Tricolia has extended into the Mediterranean Sea. Of the neritids, only the genera Nerita, Magadis, Smaragdia and Pisulina are entirely indigenous to the sea, and that only in the zones; other groups, such as Vittoclithon, warm Neritoclithon, Pseudonerita 1663 and Dostia mainly live in brackish Theodoxus, Clithon, Neritina and Septaria the 1 131 and several, especially water, in freshwater; of these only has reached Europe. Neritilia also inhabits the freshwater in first warm countries. The neritopsids, phenacolepadids and titiscaniids live in the warm seas. Neritodryas species leave the water and stay on neighboring The hydrocenids have completely adapted bushes. they are found partly lost the gill; still to aerial life on the seashore, partly and have in greater distance from the water; they have their main distribution on the coasts of Asia and the islands species found is in in the Indian are absent from America. development their richest and Pacific oceans; one Hydrocena Dalmatia and one on Tenerife and the Azores; they However the warmer in the peculiar groups as Pseudhelicina, related helicinids parts have reached of America, because such Ceratodiscus and the nonperculate Proserpininae are entirely limited to America, whereas others are more closely related to the forms living in Asia and on the Pacific islands; they are absent in Africa. The species of most cases in similarity with that of the cocculinaceans have been found in great depth of various seas. The distribution of the cyclophorids has some the helicinids, but the Asian forms and those of the Indo-Pacific islands considerably outweigh over the American Poteriinae; in Africa only a few species of the groups Maizania, Chondrocyclus, Cyathopoma and Ditropis are (?) native, in the Mediterranean region the genus Cochlostoma, and on the Canaries and Azores Craspedopoma, which related neither to The by far Maizania nor to viviparids inhabit freshwater, and from Asia, the largest number of is Cochlostoma. species, where they have they have spread to Australia, Europe, Africa and North America. Margarya, living in Tali Lake, has Tulotoma as well as some European Tertiary species; Rivularia, found mainly in mountain streams of Hunan, is somewhat similar in the shape of the a sculpture similar to that of the American southeastern shell, well as as certain Campeloma species, interpreted as a sign of closer relationship. but this Neothauma is is not to be a form from Lake Tanganyika. The origin of the ampullariids is less clear; their most may be the west African Afropomus and Saulea, perhaps primitive forms also the South American Asolene; they have reached the of species South America; the restricted in to Philippines. Africa, whereas Pila Lavigeria is sinistrally is coiled distributed largest number group Lanistes from there to is the one of the "thalassoid" snails of Lake Tanganyiaka. The the valvatids inhabit the freshwater of the northern hemisphere, in south reaching to North Africa and Central and Guatemala). America (Mexico 1664 The land-snail group of the Pomatiasids inhabits 2 separated regions: the Pomatiasinae mainly the Indo-African region, but with a few species Tudorella and Leonia they reach into the of the genera Pomatisas, Mediterranean region together with the Canaries; on the other hand, the Chondropomatinae extend to the West Indies and the neighboring parts of the continent. Of the Littorinacea, is Lacuna seems Mainwaringia species seas, the only is to be confined known from to the northern the Indian coast; uncertain whether Benthonella, living in the deep sea, is Lacuna. Laevilittorina, which resembles Lacuna in the shape of the inhabits the cold southern seas, likewise Pellilittorina; but is as known from well Island). it related to shell, Haloconcha the northern Pacific (near Alaska and the Pribilof Islands) from the South Sea (near South Georgia and Macquarie as The genus Littorina widely distributed in the is littoral zone, with few species extending into the Arctic Ocean; the subgenus 132 Littorinopsis and the genus Tectarius prefer the tropics. Species of the genus Cremnoconchus have left the shore and have climbed into the coastal mountains of India. The small group of acmids The is confined to Europe and North Africa. hydrobiids, however, which with the exception of Hydrobia inhabit freshwater, are very widely distributed. and Plagigeyeria most species occur lives mainly in Of the European also in Pseudamnicola Mediterranean region, Sadleriana in southeastern the Europe and similarly Horatia. Lyogyrus America but genera Paladilhia in springs or caves, New is found not only southern hemisphere (South and Central America, Australia, and a few islands), the in North Caledonia. The Littoridineae inhabit mainly the New Zealand Amnicoleae North and Central America, the Benedictieae Lake Baikal, the Lithoglypheae East Asia, and only Lithoglyphus also Europe. The Truncatellinae are widely scattered, some of them leave the water and stay on the shore, Geomelania has climbed into the mountains of the Greater Antilles. Hydrococcus, known only from the Swan River in Australia, was previously probably more widely and stands close to the Stenothyrinae, which extend from Australia to South and East Asia. Of the Bithyniinae, the subgenus distributed Gabbia occurs from Australia, by way of India to Africa and southern Europe, Bithynia being more western in Europe and Asia Minor. The micromelaniids were originally distributed over the largest part of Asia from Lake Baikal to southeastern Europe (Ohrid Lake), and hence the Recent species live mainly in these lakes and in the Caspian Sea; probably the genus Emmericia also will have to be placed here, but hardly the Mexican Emmericiella. 1665 The on seas, generally in shallow water, often rissoids inhabit all Cingula reaches the Holantarctic and the Arctic Ocean seagrass; — uncertain. Alvania relationship of Assiminopsis found in the deep sea is and Rissoa are found mainly Merelina near in northern seas, Of Zealand, Zebina and Rissoina in the warmer zones. the New the Barleeinae, Barleeia and Eatoniella species have been found in various seas, the former more in the northen, the latter in the south (Kerguelen to South likewise Boogina and Skenella; Eatoniopsis Georgia), The hemistomiinae live in brackish Assimineinae, which have lost their near brackish water of the higher is holantarctic. water of the Australian region. The grlls, are littoral found most cases in in or zones, and are widely distributed; on the other hand, the Omphalotropidinae have entirely climbed on land and are confined to the islands in the Pacific and Indian oceans. The groups united in the family Adeorbidae, which in part are somewhat doubtful, are scattered over northern Skeneopsis Homalogyra and Rissoella Trochaclis Of all seas, also known only from is one species in the Holantarctic. occur in the north and in the south; the Holantarctic. the turritellids, Tachyrhynchus inhabits the northern parts of the Atlantic and Pacific oceans Kerguelen, warm and Turritella the to the Arctic the Turritellopsis Ocean, Holantarctic in the solariids, temperate zones, and similarly the few species The melaniids 1133 inhabit the freshwater in Central 3 groups: America and New warm of warm and vermetids and caecids also live in the America we find south mainly the and the northern Atlantic, of the Mathildidae, of which one species occurs near In The represented in the south by Microdiscula; is Zealand; the seas. temperate zones. Pachychilus (Melanatriinae) and Hemisinus in the northern part of South America, but the Pleurocerinae in North America; the remaining Melantriinae in southeastern Asia and on the islands, in Madagascar and in western Africa. The distribution of the Melanopsinae is peculiar; of them Faunus lives in Indochina and a few islands, Fagotia in the lower reaches of the Danube and Melanopsis not only in the Mediterranean region but also on New Calendonia and most closely is a southern distributed New Zealand. The genus Semisculcospira, which related to Pleurocerinae, inhabits eastern Asia. is Amphimelania European group. Of the Paludominae, Paludomus is South Asia, the Sunda Islands, and the Philippines, Africa and Madagascar; near these stand the "thalassoid" in Cleopatra in Paramelanieae of Lake Tanganyika. The numerous species of Melaniinae are to be found from Oceania to Africa, the West African genus Pachymelania being most closely related to the American genus Hemisinus. The planaxids are shore dwellers of tropical or subtropical lands, in most cases on stones in the vicinity of tide pools or on mangrove roots; 1666 Quadrasia, found in freshwater in the Philippines, probably belongs to the Melanopsinae. The Potamidinae live in brackish water of warmer lands, mainly Tympanotonus Indo-Australian region, the in Africa similarly the Batillariinae, of which Lampanella is in found West in the Rhinocoryne on the west coast of South America. Of the Finellidae, Cerithidium pusillum (Jeffreys) lives in the Mediterranean Sea, most species in the Indo-Pacific Ocean. Litiopa, because of its life West on Indies, floating algae distributed over is all warm seas. The numerous species warm and temperate seas, the Australia. Of the cerithiopsids, of the Cerithiinae are indigenous to the only Campanile species living near Cerithiopsilla, Cerithiella species each of the two and Eumetula reach the Holantarctic, one ones also the Arctic Ocean; the only latter Of Laeocochlis species lives in the North Sea. the triphorids, only one species occurs near Europe, one in the Holantarctic, numerous species in the warmer seas. The of the scalids distribution is similar, of which a [Acirsa borealis (Beack) and Scala (Boreoscala) couple of species groenlandica (Chemnitz)] were found in the Arctic Ocean and a few in the Antarctic as well as in the deep sea. Entirely different Ocean is the distribution of the janthinids which are able to lead a pelagic mode of life because of their foam raft and have thus reached across all warmer seas. Of aclidids some species are known from the northern Atlantic Ocean and a few, some of which are doubtful, from other seas. The melanellid genus Niso, the shell of which is similar on the one hand with Hemiaclis and on the other hand with certain pyramidellids, is restricted to warm seas, whereas the other genera with numerous species are distributed over all seas, a few reaching the Holantarctic and one (Liostraca stenostoma Jeffreys) Greenland. The parasites related to the melanellids are, like their hosts, generally scattered in warmer zones, only Entocolax having been found in the Arctic Ocean and near Southern Chile. Of a few small pyramidellids (Odostomia and Angustispira) been demonstrated that they is not known whether also the larger ones. — mainly Odostomia it is live ectopasitically true of all species Most of them — has it of the family, especially are found in the in the cold Antarctic it on certain bilvalves; Ocean warmer few Fuego- seas, a (Tierra del Kerguelen) and {Odostomia and Menestho) in the Arctic Ocean. Kleinella lives in most cases in the Pacific not seem to be closely related to 134 Ocean — the Atlantic Euparthenia does it. Of the fossarids, only few species are known from various, in most warm seas, one Couthouyia from New Zealand and the Snares cases Islands; just where a few species from Fossarus belong, Vanikoro is is uncertain that area which have been called without a knowledge of the animals. native in the Indo-Pacific Ocean, except for a few somewhat — 1667 warm species. In contrast to the amaltheids living in the West Indian doubtful seas, trichotropidae the are Neoconcha, Trichoconcha which is found mainly cold the in similar to be northern seas, Torellia 1 and a couple of Trichotropsis species are holantarctic. Capulus extends from the tropics into the Antarctic Ocean (C. subcompressus Pelseneer). Of the one Crepidula species has been found in the Arctic warmer seas, the only Neojanacus species near New calyptraeids, only Ocean, most live in The Strombacea Zealand. also are restricted struthiolariids to warm inhabit mainly the seas, but the regions from Australia to the southern Kerguelen and South Georgia, and a couple of Aporrhais species reach Greenland. The heteropods the are only prosobranchs which are completely mode of adapted to active swimming and have shifted to a pelagic this adaptation has reached its life, The known highest degree in the pterotracheids. species are partly distributed over warmer all seas, part are in only from limited areas. Of is operculum, but 2 species Friele clausa Broderip & [N. bathybii and N. (Cryptonatica) Sowerb] extend into the Arctic Ocean. The groups seas, and partly entirely or predominantly sea, Friginatica in south the in warm and south as as in the near Kerguelen and in the north, Frovina lamellariids are inhabitants of cold seas to a Capulacmaea, Velutina, temperate cold water, also in the deep in still Magellanic Amauropsis region, the related Lunatia extends into the Arctic Ocean, well seas, provided with a calcareous with a horny operculum are met with partly in the the warm the naticids, Globularia and Sigaretus are native in and largely also the genus Natica which Holantarctic. the in The greater extent of with Onchidiopsis and Marsenina in the north, Marseniopsis and Lamellariopsis in the south, only Caledoniella and Lamellaria avoiding the cold water. This which in most cases are found have extended in warm is also true of seas, a couple farthest into the cooler regions (Norway, all cypraeids, of Trivia species New Zealand) likewise the Doliacea, of which Oocorys inhabits the deep sea. Like these most highly developed taenioglossans, live on coral reefs. Of the muricids, the genus many stenoglossans Columbarium inhabits generally the deep sea; Trophon not only reaches the Magallanic region with several species, but also the Holantarctic, the deep sea, in the north the Arctic Ocean, in which a few Nucella species are also found. columbellids predominantly inhabit the warm water on sand or stones, but a few species more alo found Torellia unnoticed :ed error is the correct spelling; — Editors. The seas and live in shallow Torella on original p. 132 at considerable is apparently an 1668 depths; some species Bounty Islands and have been found the south near the in Snares one [Pyrene (Alcira) transitans (Murdoch)] Islands, Campbell Island and few species near Patagonia, only one also near the [Pyrene (Astyris) rosacea (Gould)] extends into the Arctic Ocean. 135 Buccinum undatum Linne is stated to live on ever}' kind of substratum, from the coast to considerable depths, and hence the family also seems to have easily adapted to the most diverse conditions and can be encountered in a considerable number of species not only in warm but also in cold seas; represented in the north are the genera Buccinum, Liomesus, Mohnia, Beringius, Volutopsis, Plicifusus, Sipho and Neptunea, Neobuccinum, the groups in the south Prosipho, Pareuthria, Chlanidota, Chlanidotella, Proneptunea and Meteuthria, also Glypteuthria, Savatieria, — Antistreptus and Fusinella larger than the southern. and strong from the cold shells, are absent most cases much the northern forms are in The Galeodidae, which most cases have large in seas, the same is true of the small Nassidae, of which only a couple of species live in the deep sea, and the Fasciolariidae. The Pseudolivinae are and South Africa, except for the West present native near at less closely related Zemira from East Australia; the Olivinae are restricted to the tropics, as also the Harpidae and as a whole also the Mitridae, of which only individual species occur at greater depth, and the Vasidae, the genera of which are perhaps not closely related to one another. Metzgeria and Ptychatractus live in the 1 North Atlantic Ocean. The volutids largely lands and burrow into sand at low live near the coasts some groups tide but Fusivoluta, Phenacoptygma, Neptuneopsis, Harpovoluta, Tractolira) in Volutomitra is the deep sea, some of them the in of warm {Volutocorbis, and Guivillea Antarctic Ocean; represented with a few species in the Antarctic Ocean between South Georgia, Australia and Kerguelen, and one species [V. gronlandica (Moller)] in the North Atlantic Ocean. Cancellaria species are in most cases found in shallow depths of warm seas, the few Admete species are on the other hand mainly in the polar seas, one in the deep sea near Mexico and one near East Africa; Benthobia seems to occur in the deep sea not only on the American side but also on the African side of the Atlantic Ocean (cf. "Lacuna" cossmanni Locard). The marginellids are found not only in the tropics but also in cool seas, numerous species near South and West Africa and in the West Indies, partly at considerable depth, in the Mediterranean Sea and near the Iberian coast, one small species in the Holantarctic. Among of which is in most cases the numerous species of the Turridae, known only information for classification into the genera, in warm and shallow water, but many the also at depth and in few an the polar seas. In providing shell, little many have been encountered more or the less considerable Arctic Ocean almost 1669 exclusively species of the genus Lora are present (in addition to one which are perhaps a few species few species Drillia, Pleurotomella of Thesbia, in the Antarctic and probably Leucosyrinx. Almost of these genera have also been found the deep sea, and with in Gemmula, Ptychosyrinx, Pontiothauma, especially Ocean rightly placed in Lora, besides there are a Mangelia and one Taranis species), all them Gymnobela, Typhlosyrinx, Eubela, Gymnobela, Borsonia, Bellardiella and Mangelia. The Coninae reefs, live mainly in tropical seas, living in holes rarely at considerable depth; and cracks of the distribution of the terebrids is similar. Of the actaenoids, species from great depth and from the Antarctic Ocean have been placed the animals and in the genus Actaeon, but without knowledge of very doubtful is it Bullina; 136 The New correct; the true species regions, but A. tornatilis Solidula (Linne) extends to the Lofotens. region, southward to is warm if this appear to live near the coast, mostly in Zealand, but inhabits the Indo-Pacific missing near America, likewise is Neactaeonina appears to be restricted to the Antarctic Ocean. ringiculids and hydatinids are native in on the other hand mainly in cold seas, species and Newnesia in the Antarctic. are encountered mostly on sand banks warm seas, the diaphanids Toledonia except for one northern The bullariids are plant eaters at the river mouths or and in brackish water pools, in deep water of warmer seas; the atyids have similar habits, Cylichnium appears to occur only in the deep sea. Acera feeds mainly on seagrass and it is widely distributed with few species which are mostly found on muddy substratum of the coast. The small Retusidae inhabit the ocean floor to considerable depth and feed in most cases on foraminiferans, also Scaphandridae, large Scaphander species similarly the overpower much larger prey, such in part also as Dentalium; these groups are represented in the cold seas, in the Arctic Ocean Retusa, Cylichna and Scaphander, in the Antarctic Ocean only Cylichna. Species of Philine also occur Broad lateral cephalaspideans, in both polar seas. margins of the foot are used for swimming by some such as Cryptophthalmus (cf. Fig. 488), Acera, Gastropteron, but the animals mostly stay on the plants, which perhaps in addition to sinense A. small animals, Adams seems to also serve as their food; Gastropteron be best adapted for a pelagic mode of life. The Aglajidae swallow animals which they can overpower, and in most cases are native in shallow depths of warmer seas. The aplysiids are plant eaters, living in shallow water of tropical and temperate zones, only one species (Dolabriffera holbolli Bergh) near Greenland; able to swim, Notarchus some of them are by contractions of the fused parapodia which expels water from the respiratory opening, so that the animal is driven 1670 forward like the cephalopods. A completely pelagic mode of life has been adopted by the pteropods which are found partly in all seas, partly only in warm Ocean regions; in the Arctic Spiratella helicina (Phipps) and CUone limacina (Phipps) are especially common; the thecosomes feed mainly on microscopic plankton, the cymbuliids also on copepods and only on various small animals but also on sagittae, the pterotans not larger thecosomes. The sacoglossans which serve as live in shallow water on seagrass and other plants their food, only Elysia viridis capitata (Muller) reach Finnmark and the (Montagu) and Limapontia Murman coast; the group not is The notaspideans, which swallow buccal mass, occur in warmer seas, represented in the cold southern seas. available prey with their large all partly on the shore, partly (Bergh)] one species [Bouvieria platei at greater depth; was found near Chile and on the Burdwood Bank the in Antarctic Ocean. Odhner observes in connection with the naked opisthobranchs, that homogeneous jaws is common to the Doridoxidae and Bathydorididae along with the Arminacea and Dendronotacea, to which the possession of the Duvauceliidae and Dotonidae are allocated, and that this group which may be as Gnathodoridacea placed opposite the jaw-less Eudoridacea, is represented only in the northern and southern colder seas and in the deep sea, whereas the Eudoridacea have a cosmopolitan distribution. The genera Cadlina and Aegirus are native mainly to the cold seas, and similarly Cuthona, the Antarctic Prodoridunculus is the related to northern Doridunculus, corresponding to the northern Goniaeolis in the 1137 south are the Charcotiidae with the genera Charcotia, Pseudotritonia and Telarma Odhner 1934, Notaeolidia known only from is the Antarctic Ocean. The fish-shaped phyllirrhoids lead an entirely pelagic warm seas, the tethyids life in from time to time; Scyllaea pelagica Linne, Spurilla sargassicola (Kroyer), Glaucus and one Corambella species live on sargassum. The ellobiids, which are phyletically considered the oldest nonoperculate pulmonates, are in most cases shore dwellers but Pythia is far found in forests near the coast, and Carychium from water under decaying wood and most cases live in water or in the tidal accessible coasts; most of them are groups in may have developed Ocean and were still be encountered zone, their reproduction correspondingly different. The oldest forms the Carboniferous along the Indian is to fallen leaves; other native to is also during distributed over the warm zones, Carychium species being found from East Asia (Japan, Philippines, Java) through the entire Palaearctic region as well as in the United States to closely related Zopeum occurs in Mexico; the Karst caves; species of Pseudomelampus, 1671 Ovatella and Alexia have reached the European coasts, as also Otina. Whereas the few species of the amphibolids are restricted to coasts of the Indo-Australian area, the siphonariids are widely distributed, especially in warm zones of the southern hemisphere, but one species found is in the cold southern sea to Kerguelen and Patagonia. Among the freshwater pulmonates, the chilinids are restricted to the more southern parts of South America, the latiids to other families however have spread over New Zealand, the of the world, some parts all genera and subgroups occur only in certain regions; the very peculiar Lanx only in Africa. Anisus Segmentina New North America, Isidora from and southern Europe, Planorbula to Africa is in Zealand and Australia America and northeastern widely distributed, especially the subgenus Gyraulus\ absent from America; Choanomphalus lives only in Lake is Baikal, as also Pseudancylastrum; Acroloxus in Europe; of the ancylines, Ferrissia has the widest distribution, but it is replaced by Ancylus; Amphigyra and is absent from Europe, where Rhodacmea are North American groups. The oncidiids are shore dwellers, presumably having arisen from a shell-bearing southern littoral form (Actophila); of the genera, Oncidiella has the widest distribution, extending in the south to Campbell Island and Patagonia, in the north to Alaska and southern England; Oncis to the Indo-Australian region, similar but extending Oncidium. Of found only Australia, the two families of the somewhat is limited farther is soleoliferans, the Rathouisiids are Southeast Asia, on the nearby islands and in eastern in on the other hand the vaginulids are much more widely warm parts of America in the palm zone, a few species found in Australia may have been introduced. The genus Succinea is found in all continents and on many islands, distributed and inhabit Ethiopia and the one species Greenland, in Homalonyx are restricted, it is to absent in New Zealand; the related genera South and Central America, Hyalimax to some islands in the Indian Ocean and Indochina; the athoracophorids, which probably are related here, inhabit the Admiralty Islands, New New Caledonia, the The home of 1138 species Hebrides, Australia and New Zealand. the Achatinellacea are the islands of the Pacific, having reached westward to Mauritius, others few have spread eastward and have reached the Galapagos and Juan Fernandez, few have reached Pacific New Zealand; the amastrids and partulids also live only on islands. The distribution of Cochlicopa is quite different; the northern part of Asia and North America, the whole of Europe to North Africa, Madeira and the Azores, the related Azeca lives in the Mediterranean region and Central Europe to England. The small vertiginids have spread mainly over the lands of the northern hemisphere, especially 1672 Eurasia, but in part have also extended more or considers the following as endemic; Gibbulina in South Africa, Campolaemus in St. less far is southward; Pilsbry South America, Fauxulus Helena, Costigo on Indo-Malayan and Melanesian Islands, Cylindrovertilla in tropical Australia and Melanesia, Lyropupa on the Hawaiian Islands, Pronesopupa and Pupoidopsis on the latter and Polynesia. The valloniids also inhabit mostly the northern hemisphere, only Pupisoma and Strobilops have also extended into the southern continents. The Enidae are completely absent from America and almost entirely from Australia; the Ethiopian forms belong to the Napaeinae without spermatophore sack. The clausiliids perhaps also spread out from eastern Asia, only the small group of Nenia, Peruinia, Temesa has reached South America, and Macroptychia with few species has reached Ethiopia; the great majority of species are found in Asia and Europe, some of the genus Boettgeria on the Canary Islands. Of the Hohenwartiana, Ferussacia, Cryptazeca ferussaciids, the genera and Calaxis are indigenous entirely or predominantly region, Caecilioides being considerably on the East African West to the New Mediterranean distributed not only islands, in southern Africa, in India, and perhaps introduced on also in the more widely on the Philippines, Caledonia and the Hawaiian Islands, but Indies; Coelostele is also found outside the Mediterranean region in Mexico and India. According to Pilsbry, a species found in the Eocene of Italy Mesozoic, but Africa, proves that the genus probably developed in the European its may have been point of origin where according developed. There the to latter Pilsbry's further south, hence in assumption the subulindis also have achieved their richest development, and have spread with some groups westward and eastward across the warm zones; probably the ancestral forms of the Megaspiridae also arose in Africa, but became Europe (Palaeostoa Andreae), so that extinct as in at present they are found only in Brazil, as well as in Australia (Coelocion) New Guinea, and Obi (Perrieria). On the other hand, the achatinids are completely confined to Africa. The most primitive forms of the Oleacinidae live may conclude that it was their home, but European species are known from the Cretaceous on, only in tropical America, from which one original and Pilsbry therefore considers it probable that they have originated from the Archhelenis. Perhaps the testacellids of the Mediterranean countries are also to be derived from such ancient oleacinids. Because the very ancient endodontids are distributed over continents, their origin is all uncertain, although the great richness of forms of the Indo-Australian region may rate the Discinae, indigenous to indicate that they arose there; at any Europe and North America, are probably — 1673 not very primitive. They are strongly represented in New Zealand, the southernmost form being Notodiscus hookeri (Reeve) on Kerguelen. The 1139 America polygyrids, placed by Pilsbry in the Helicacea, live in North to Mexico and Honduras and on some mainly on the Antilles and to On be out of the question. islands, the Sagdidae America; their origin in the other hand, Sculptaria is in Central Asia seerris indigenous only in South Africa, Corilla in India, and Plectopylis in India and China; Degner has emphasized the similarity of the mantle organs and reproductive apparatus of ttyese genera; the furrows on the foot in the their relationship. The first presence of lateral the of these alone would hardly contradict zonitids are almost entirely limited to the northern hemisphere, aside from a few introduced species and perhaps Zonitoides species in Brazil. The home of the systrophiids is in South America, beyond whose borders only a few species extended. The have vitrinids probably spread from East Asia and have extended mainly westward, so they have advanced through Arabia to East Africa and through that Europe to the Canary Islands and the Azores, only few species have migrated eastward to North America, and one species related to the Philippine Vitrinoidea southward to arionids is similar, the New Zealand. The situation with the most primitive form of which {Binneya) having a shell similar to Vitrina and living in California extended partly somewhat more toward the toward the west, so that they are found not only also in western Europe and a branch of the arionids, The in and Mexico; the genera east, in partly North Africa. Oopelta which has migrated distribution of the philomycids into more or less Asia (Anadenus), but may be considered West and South Africa. considerably different, proceeding is perhaps from western North America, having spread across the United States and Central America, and on the other hand (Meghimatium) to East Asia and the nearby islands, but did not extend further to the west. original home of the limacids seems to be Asia, from where they have spread mainly toward the west across Europe and North Africa to The the Canaries; Agriolimax has the greatest distribution, in the south occurring in Abyssinia, a few species also occurring in North America some species of the genus Milax also have become widely The trigonochlamydids are restricted to Asia Minor. The most primitive group of the ariophantids is very widely in addition introduced. distributed; Kaliella in the Indo-Pacific region, in tropical hemisphere. areas, America, and Euconulus in Guppya and Habroconus different parts of the northern Related groups inhabit more or less narrowly delimited and none of them has reached Europe and America; the family most strongly represented in Africa, is South and East Asia and on the islands in the Indian and western Pacific Ocean. 1674 The acavaceans, proceeding from ancient the "Gondwanaland," become more spread over the lands of the southern hemisphere, having or less modified, the South African Trigonephrus is be seen as the to most primitive form; the Madagascan and Australian groups show considerable differences, the South American strophochilids are related to the dorcasiids, but whether the Chilean Macrocyclis, the shell form of which similar to that of Dorcasia, is According to Pilsbry, is uncertain. the bulimulids have developed in South America, where they are most richly diversified, and have probably migrated across Antarctica Guinea, Solomon and 140 toward the east, and Tasmania, Placostylus from lives in Australia 1 (?) Fiji where Bothriembryon New New Zealand to but the South and Islands; West African genera Prestonella and Aillya, recently placed in bulimulids, must have come across the Archhelenis. However, the family has also advanced northward across Central America and the Antilles into the southern United States; in this region the cerionids and urocoptids have originated. Because the helicaceans undoubtedly arose from the same root as the acavaceans, they would also have had the same original home, from where they migrated further northward and then gradually toward the east and west, so that they reached all continents with various groups; they are most sparsely represented in tropical Africa, mainly in the mountains of Abyssinia and further south. The affinities still assumed by Baker of the haplotrematids, which are America and the West native in North Indies, with the paryphantids, are unclear; the latter are mostly distributed in southern lands, a New genera in few Zealand, others in Australia and the islands of the Pacific where the aperids have originated. The great as well as in South Africa, resemblance of the South American Martinella with Imperturbatia, which is known only from originated from a and is now the Seychelles indicates that both groups have common ancestor, extinct; the latter also which presumably lived may have in Africa stood close to the Helix- shaped genera Tayloria and Scolodonta. The streptaxids currently live not only in Africa, where they have produced a very large variety of forms, and in South America, but also in South and East Asia to the Philippines. The scapophods into are exclusively inhabitants of the sea the substratum. According to distributed in all seas, the Pilsbry, and burrow the genera are as a whole subgroups are more or less localized. Of these Siphonodentalium, Fissidentalium, Heteroschima, Bathoxiphus, Rhabdus, Episiphon and Compressidens are almost entirely deep-sea forms; Dentalium shore. Few s. s., Antalis and Graptacme are found in most cases on the species occur in the Arctic Ocean, others in the Holantarctic. 1675 Of very ancient taxodonts, the nuculaceans are burrowing the animals and hence live in sand or mud; because they find such substratum at the the most varied depths, they are correspondingly distributed, but, as some genera and subgroups occur case of the scapophods, A limited regions. Ocean few Nucula species extend to Greenland, N. tenuis deep-sea species known from is have been found (Montagu) in Atlantic circumpolar, only one small is Most of the malletiids the Holantarctic. deep or cold water, as also Ledella and Yoldiella; Portlandia isonota (Martens) from Kerguelen (Gray) from the Arctic Ocean. arctica the North into in in very similar to P. is and Leda are widely Yoldia Most of distributed like Nucula, likewise Solenomya. the arcids have a well-developed byssus, with which they attach themselves to stones and rocks, so that they are mostly found in not very deep water, but more or groups, especially Acar and Bathyarca, have byssus, in adaptation to at life considerable depth; Scaphula species have migrated into Limopsis is the seas, mainly distributed in the Pleurodon species in of India. rivers less some rudimentary only the small Of the limopsids, deep seas and extends into the cold most cases shallow depth; the in remaining groups are almost exclusively inhabitants of the southern seas between Antarctica and Australia, South Africa and Patagonia, one species of Philobrya has been found near Juan Fernandez and one species near California. The Glycymeris species have completely lost their byssus and have acquired a burrowing foot similar cases in warm to that of nuculids, they live in most seas at shallow depth. The distribution of the mytilids is similar to that of the arcids, the Dacrydium species being native to the cold and deep seas, most groups live warmer and shallower in water, a few Musculus and Crenella species extending into the Arctic Ocean; only a few small species are found in the freshwater of Southeast Asia. The Pteriacea are inhabitants mainly of the warm parts of the Indian and Pacific oceans, only few species have reached the The genus Dimya Japan, one species in West Indies and Europe. Ocean from The Amussiinae also lives in the Pacific the West Indies. indigenous to cold and deep seas in contrast to the Spondylinae, which are almost completely lacking Pecten (Chlamys) islandicus (Miiller) living limids live in the warm and temperate in seas, a in deep of the genus Anomia are scattered over warm and The cold seas, only The Limatula group extending into the polar restricted to the Indo-Pacific region. the mostly few large Acesta species seas. Species is are Pectininae and the Arctic Ocean. in the Pacific sea, only the Australia to The all ostreids live seas, Placenta on the coasts of temperate zones. trigoniids, which were widely distributed in the Mesozoic, are 1676 present restricted to at Australia. As few species of the genus Neotrigonia near far as the freshwater unionaceans are concerned Pilsbry has expressed the opinion that the original group split into 2 branches, one of which, the mutelids, developed in the south on the GondwanaArchhelenis continent, and the other, the unionids, in North America and The genus Diplodon probably Asia. has — and perhaps across Antarctica New (?) — originated in South spread to New America and Zealand, Australia Guinea, on the other hand the Mutelinae with species of the genus Anodontites have reached Mexico and with other groups, across the Archhelenis, have reached the east and distributed in tropical Africa. distribution of the aetheriids is similar, of which one species, Pseudomulleria dalyi (E. Smith) has reached to India. Like the The margaritanidae, the Unionidae essentially inhabit the northern hemisphere, but some groups have extended southward, especially into Africa, where they have arrived from Asia; they reached their greatest richness of forms in The North America, East Asia, and the Sunda Islands. astartids are native mainly in the North Atlantic into the Arctic Ocean, one Digitaria species has been found near Port Alfred and one warmer Astarte in the Holantarctic; Crassatella inhabits the small genus Cuna, the systematic position of which near Australia, carditids live in New is seas. The not clear, occurs Zealand and South Africa (Port Alfred). The most cases warm in seas not far from the coast, only the group Cyclocardia having advanced into the Arctic and Antarctic regions; the distribution of the condylocardiids is predominantly southern. Only few species of the Sphaeriacea live in brackish water of the coasts, most of them have wholly migrated into freshwater. The more or less large, thick-shelled corbiculids have spread across the tropics, radiating presumably from South Asia; the group Cyanocyclas is South American, and the American groups of the genus Polymesoda extend into the southern United States; the smaller sphaeriids have reached continents, especially with the genus Pisidium; Byssanodonta 142 is is known alive only from Africa and South to Central all = Eupera America; Sphaerium absent in the Indo-Australian region, but one species has been described from New Zealand. The very variously sized Kellyellidae inhabit the deep sea, the species of the isocardiids the warm are at present represented only seas in shallow depth. by one species The few cyprinids in the northern Atlantic Murman coast, on the other hand the libitinids live reefs of warm seas. The cyamiids are a group of small to Greenland and the in rocky and coral species in the southern seas from the Holantarctic to Australia, most of the neoleptonids also occur in the south, but coasts. The gaimardiids some also are also completely southern, closely related to the cyamiids. on the European and are probably 1677 The Dreissenidae live in freshwater of Africa, Europe the central parts of America, their fossils are Miocene; their origin Of is Asia and to East known from the European unknown. the Lucinacea, in most cases small Thyasirinae are found mainly and deep oceans, the Ungulininae mostly in cold Diplodonta species live in the warm in seas, but 2 Ocean; the same Arctic Lucinidae, only few of which occur in deep or cold water. is true Some of the Erycinacea are widely distributed, some of them extending polar seas, others are known only from absent in the cold seas. Ocean and Of limited areas. the cardiids, Serripes is the boreal parts of both oceans, few to the The chamids the tridacnids only in the are native in the Arctic Cardium species extend into the Arctic Ocean, but most of the species live in the seas, of genera The Indo-Pacific region. also warm species-rich Veneracea inhabits the oceans of warm and temperate zones, mostly at shallow depth, only a couple of Liocyma species extend into stirps — the Arctic Ocean species known from is similarly the Mactracea, of the Arctic Ocean. which only one Spisula Most of the Tellinacea live warmer lands, Iphigenia and Egeria in brackish water of America and West Africa, Profischeria in rivers; some Macoma close to the coasts of Most of the solenids live in sand zone of warm and temperate lands, only one species Siligua media (Gray)] is reported from the Arctic Ocean; Novaculina and the species are native in the Arctic Ocean. in the tidal glaucomyids have penetrated into South and East Asian rivers. The saxicavids live partly only in the Arctic Ocean, but the genus Saxicava distributed in all seas, in the south to Kerguelen, and Panopea inhabits The Myacea are found in shallow depth, Aloidis predominantly in warmer seas, Anticorbula and Erodona in South American rivers, the few Mya species in the arctic and boreal sea. The is deep waters of various seas. Gastrochaenacea and Adesmacea, which in most cases bore into solid bodies, extend from the tropics to temperate zones, one Teredo species to the Murman coast. The Anomalodesmata are in most cases insome genera habitants of the deep sea or cold seas, but a few species of occur in shallower and warm water, as also Myochama, Chamostrea, Parilimya and the The primitive shell-bearing cephalopods life similar to that of the some genera, such as clavagellids. certainly lead a few Nautilus species presently mode of living in the Indo- Pacific region. These generally live in shallow depth near the bottom, being moderately capable of swimming movement with the help of their cone-shaped funnel, and of crawling on their arms. At the same time the 1 143 orthoceratites may have lived more pelagically; at all events they did not stick in the substratum with the end of the shell. All cephalopods live on animal foods, especially on crustaceans. Spirula lives bathypelagically 1678 warm in the seas, in the south to and backward with the fins New Zealand; can swim forward it and the funnel. The sepiids are littoral animals, which are absent only from the polar seas, on the other hand Rossia species occur not only in the Arctic Ocean, but also in the deep sea, the pelagic Heteroteuthinae are distributed in the Loliginacea and Architeuthacea also lead a pelagic of them warmer mode of seas. life, The some considerable depth and are then not seldom provided with at light organs; some of them have achieved considerable and thus a very wide distribution, especially in the swim ability to warm and temperate known exclusively or predominantly from cold seas, and Alluroteuthis from the Antarctic Ocean, zones. Only few are Psychroteuthis Crystalloteuthis from the Antarctic and the northern Pacific; Gonatus, Moroteuthis and Ommatostrephes occur in the cool seas of the north and south. Of the octopods, the Vampyroteuthacea and Cirroteuthacea are inhabitants of the deep sea; the Opisthoteuthis species on the bottom, others lead a more pelagic Argonautacea also lead a pelagic Among life, life. may generally live The Bolitaenacea and the former at considerable depth. the Octopodacea, the Ozaeninae and Octopodinae differ from the Bathypolypodinae, which in most cases occur in the deep sea and in cold oceans, because they live in the vicinity of the shore. It to is be assumed that the ancestral metazoans lead a pelagic movement being performed solely by epithelial cilia, as shown by the ctenophorans, whereas the ancestral bilateral animals became bottom dwellers with creeping locomotion. From such animals, probably now entirely extinct, which presumably had a body form existence, their is resembling that of the turbellarians, the ancestral forms of the mollusks have developed, and the formation of a dorsal wave first as a protection from the that the animals lived near the coast. may have shell action at the surface, hence The muscular, served it is at likely sucker-like foot were mostly attached to solid bodies, such as indicates that the animals rocks and rubble, and scraped off encrusting plants by means of their radula. Their mobility was very slight, and therefore, in order to ensure a certain possibility of dispersal, they retained a ciliated larval stage in their ontogenetic development. Many primitive mollusks, such as the loricates, haliotids, patellids, have permanently retained this life style and the coast as habitat. The arcids also do not seem to have left themselves in one place for a longer period of time, they fasten this habitat; in order to maintain themselves to the substratum with their byssus, and nourish themselves on small organic ciliations of the particles gills and which are directed toward the mouth by the labial palps. Because plant life is possible only 1679 to depth of about 400 m, numerous species are confined to the Some of them have left the solid substratum and have a continental shelf. moved to sand or mud; the foot soon acquired the capability, especially by expansion of the lateral margins, of moving on the surface of the loose substratum at times burrowing into it, as it is done not only by 1144 many snails, but also the scaphopods and many bivalves. Certain snails on Zostera and algae have acquired a characteristic adaptation; among these the species that stay on the pelagic Sargassum, and whose relatives are native in most cases to the coastal regions, are worthy of that live special Many note. gastropods, especially the higher prosobranchs, are also part of the rich animal life of the coral banks. These different coastal habitats are most cases very extensive in without being interrupted by others, and there by granting even the not very motile snails the possibility of wide dispersal, which mainly by the ciliated larvae. the adult stage to proceed further and is possible by creeping, these are more Pleurobranchidae, Tethyidae) and life, all some among swimming ability in and opisthobranchs olivids Aplysiidae, Lobiger, bivalves some Pectinidae and of these however have not given up their benthic but use their effected by swimming than rapidly (Cryptophthalminae, Acerinae, Gastropteridae, Limidae; is Only few have acquired the capability mode of only temporarily for the purpose of a change of location. The species living on loose substratum are in part on whether they live at lesser or greater depth, little dependent because everywhere they find sufficient nutrition, consisting mainly of organisms that have sunken from the surface, and accordingly they occur at times depths. Differences of the water temperature are of at very different little importance to them, and climatic conditions generally exert only a slight direct influence on the distribution of of more or less great many molusks, even From such have come those organisms). groups, depths, that sea; if indirectly importance (breakers, currents, which can descend ice, effect species, on food considerable into have completely adapted to they are sometimes only individual they are life in the deep sometimes entire genera, such as Pectinodonta, Calliotropis, Basilissa, Sequenzia, Guttula, Gaza, Callumbonella, Chunula, Cocculinacea, Benthonella, Oocorys, Columbarium, Guivillea, Volutocorbis, Fusivoluta, Phenacoptygma, Neptuneopsis, Cryptogemma, Benthomangelia, Marginellona, Leucosyrinx, Ptychosyrinx, Typhlosyrinx, Pleurotomella; Pontiothauma, Bathyclionella, some scaphopods (cf. p. 140); Tyndaria, 1 Neilonella, Bathyarca, Idasola, Kellyella, Mytilimeria, Myodora, Pholadomya, Panacea and most of the Poromyacea, are completely or Malletia, predominantly found in the deep sea. 1680 Only few groups of gastropods have assumed an entirely pelagic life. This has happened in a very peculiar way in the case of jathinids, which have acquired a passive swimming ability by means of mode of The fin of the heteropods has certainly from the propodium of related snails, perhaps through forms that could execute jumps by means of their foot. The a foam raft attached to the foot. originated transitional pteropods stand close to opisthobranchs with strongly broadened margins of the foot, which correspond The phyllirrhoids are also unique. acquired swimming near the surface, at to the fins. entire class life, at times times at considerable depth, but some of them have assumed a predominantly benthic mode of 1145 of the cephalopods has and most of them lead a pelagic ability, lateral The completely pelagic life (cf. p. 1677). Coastal inhabitants, that lived near river mouths, found their into brackish water themselves to and under certain conditions into the in freshwater; this has life happened in rivers, way adapting some groups of gastropods (Theodoxus, Neritina, Septaria, Neritilia, Viviparidae, Ampullariidae, Valvatidae, Hydrobiidae, Melaniidae, Clea; Chilinidae, Latiidae, Physidae, Lymnaeidae, Planorbidae and Ancylidae) and bivalves Scaphula, Sinomytilus, Unionacea, Sphaeriacea, Dreissenidae, Iphigenia, Glaucomyidae, Novaculina, Anticorbula and Erodona, in part they have reached completely isolated bodies of water. Other coastal inhabitants reached the from time to time deprived tidal zone, where the shore was of water; some protected themselves from desiccation of the gills by burrowing into the wet sand, others have or less adapted themselves to some have others retained their have completely life in gill, lost the air. although it at Among more these littoral snails times somewhat reduced; {Hydrocena, Assiminea, Ellobiidae, Oncidiidae), and near these stand those that have fully migrated to dry land (Georissa, Cyclophoridae, Pomatiasidae, Acmidae, Helicinidae, Carychium, Soleolifera and Stylommatophora). The littoral habitat thus plays the most geographic distribution of the mollusks. coasts It important role in the essentially corresponds to the of the continents together with the neighboring island groups. Based on climatic conditions, 3 zones are distinguished; an Arctic, a and an Antarctic. In the Arctic zone, the ocean basin is enclosed by the northern coasts of the continents and of the island groups, and tropic, these coasts directly continue into the southward running coasts of the Atlantic and Pacific warmer regions east coast of making it possible for the animals to spread from the into the Arctic Ocean. Hence, the coasts of Norway, the North America and the coasts of the Bering Sea represent transitional areas, and only a few species are completely restricted to the Arctic Ocean, while most extend into the boreal region. 1681 The situation of the Antarctic zone is very different, which not only includes the coast of the Antarctic continent (Holantarctic) but also the more or and Tierra del Fuego. This zone less distant islands taken to include also a part of New is mostly Zealand, the south coast of Australia, South Africa and a considerable part of South America, but their fauna is considerably different from the Antarctic one. The islands from may be Kerguelen to South Georgia distinguished as Metantarctic, the Magellanic and Aucklandic regions, which contain a mixed fauna, as Parantarctic. The shells of the mollusks living colorless and of this the Arctic shells affinities strength, little in the cold seas are in most cases sometimes with because of ribs or rings; have some similarity with Antarctic ones, and close between the two areas have been inferred, which however more information did not always confirm; nevertheless, several genera were found to be essentially bipolar; Lepeta, Margarites, Torellia, Laskeya, Admete, Lora, Thesbia, Diaphana, Cerithiella, Turritellopsis, Volutomitra, Toledonia, Thyasira; Cylichna, Philine, evidently Cadlina; Limatula, Astarte, some of them are also Cyclocardia, known from other zones, especially from the deep sea. This circumstance allows the conclusion 146 that a migration deep between the cold regions has taken place through the groups sea, although certain may have used the meridional coasts for this purpose. Regarding the direction of such migrations, the assumption has to be rejected that they have taken place southward from the Arctic Ocean; rather they started from intermediate regions, which however often lay far to the south. Groups such as the buccinids, which are strongly represented in the Arctic Ocean, probably greater depths, first descended to from where they reached the Arctic Ocean; the Antarctic buccinids are not closely related to the Arctic ones, Neobuccinum having a radula different from that of Buccinum, whereas the latter genus has a dentition like that of the South African genus Burnupena. Numerous genera are Nuttalochiton, Submargarita, Pellilittorina, Perissodonta, Savatieria, Guivillea, Notochiton, Trochaclis, Frovina, seldom South Australia: Hemiarthrum, Tonicina; Icoplax, Eatoniella, Neobuccinum, Prosipho, Lamellariopsis, Prodoridunculus, Marseniopsis, Thalassoplanes, Pareuthria, Fusinella, Provocator; Newnesia, Neactaeonina, Holoplocamus, Margarella, Nacella, Boogina, Skenella, Laevilittorina, Microdiscula, Chlanidota, Antistreptus, only the Antarctic region, they native to largely reach the Magellanic region, Austrodoris, Glypteuthria, Harpovoluta, Tritoniella, Gargamella, Bathydoris, Notaeolidia, PSeudotritonia, Charcotia, Telarma, Galvinella, Guyvalvoria; Adamussium, Adacnarca, Lissarca, Philobrya (except for a few species), Gaimardia, Cyamiomactra, Perrierina, Cyamium, Pseudokellya, 1682 Ptychocardia. Because a few species and several genera live near the Kerguelen and in the Magellanic region it is to be assumed that earlier a connection existed between them; probably the Holantarctic was also colonized from this region, while it mediated the migration of more northern forms mainly from South American coasts. Genera that extend only into the Magellanic region, but are absent from the Antarctic proper, Plaxiphora, are: Chaetopleura, Acanthochiton, Notoplax, Ischnochiton, Chiton, Tonicia; Fissurella, Acmaea, Calliostoma, Photinula, Chlorostoma, Fusitriton, Calyptraea, Crepidula, Lamellaria, Columbella, Buccinanops, Cymbiola; Mytilus, Carditella, Carditopsis, Chione, Mulinia, Barnea. Some of these groups also occur in the Aucklandic region, whereas others are lacking; the following are not found in Magellanic region and in the Antarctic: Cellana, Haliotis, Cantharidus, Monodonta, Trochus, Turbo (Modelia), Littorina (Littorinopsis), Couthouyia, Nucella, Cominella, Euthria, On other the Mitromorpha, Daphnella, etc. hand the following may be designated as characteristically Arctic forms, generally also living in the Boreal region, but absent from the Antarctic: Tonicella, Stenosemus, Symmetrogephyrus; Lacuna, Molleria, Capulacmaea, Velutina, Marsenina, Onchidiopsis, Liomesus, Beringius, Volutopsis, Mohnia, Sipho, Plicifusus, Ancistrolepis, Sulcosinus, Neptunea, Coryphella, Chlamylla, Buccinum, Doridoxa, Dendronotus, Egalvina, Cumanotus, Cuthonella, Goniaeolis, Precuthona; Cyprina, Serripes, Panomya, Cyrtodaria, Mya. When some of these groups occur only in the northern Atlantic Ocean or in the Pacific Ocean together with the neighboring parts of the Arctic Ocean, one that the direction of their migration is may assume many are thus indicated; however, circumpolar and are distributed in both oceans so far southward that is it say where they originated. one no longer included the southern parts of South America, difficult to If Africa and Australia in the tropical zone, their coastal regions are divided ] 147 4 separate subregions: the Indo-Pacific, the western American, the eastern American, and the West African. In spite of this separation, there into are in part very striking affinities between these areas; thus the Indies there live not only many genera West but even a few species that also occur in the Indo-Pacific region. This can be explained only by the fact that in earlier times the coasts of both areas were joined in the equatorial direction, the Ethiopian part of Africa being connected with South America; moreover, South and North America were separated from one another. Jhering says about this; "In the early Tertiary there existed between the eastern and western parts of the Tethys Sea a continuous active faunal interchange, which presupposes a free oceanic connection across the Sudan, and secondly: the Eocene migrations of marine Indian 1683 organisms to the West Indies could have taken place only along the coast of long vanished continents of the central and southern Atlantic." Several of these animals lived previously also became in the European region, but extinct as a result of local and climatic changes. The significant difference of the mollusks of this tropical zone in comparison with those of the Antarctic may have as its prime cause northern coast of this large continent with from different of that its Patagonia at as Nereis. the beginning of the Tertiary, but New Zealand and Australia. On it may have also been the other hand, Africa have been without a direct connection with the Antarctic. The to New Amsterdam islands of St. Paul and show known very probable that the Antarctic continent was connected with is connected with seems the nature of the south coast, between which and the Antarctic continent extended the ocean It that communities was basically its certain affinities Zealand. Tristan da with in the southern Indian South Africa, and probably also to Cunha and Gough Ocean New Island in the southern Atlantic also have no relationship with the Antarctic. The dispersal capability of those animals that are adapted to life in the ocean depths is very different, encountering certain limits perhaps only through the nature of the substratum, but some deep-sea species have been found in widely separated places. The situation is similar in the case of pelagic animals, especially those that possess a permanent swimming active capability, such as that acquired among mollusks mainly by the cephalopods. The heteropods and pteropods, as well as the phyllirrhoids also lead a permanent pelagic life, although their locomotion swim over large distances; the janthinids are completely passive, being moved only by the ocean currents and the winds. These animals live in most cases in the warmer seas, but some pteropods have more or less largely withdrawn from the equatorial is not so effective that they can regions, partly to the south, but also to the north; completely adapted to both cold-water regions are Spiratella helicina (Phipps) and Clione limacina (Phipps). The freshwater habitat shows highly peculiar conditions. Although mouths is possible without the migration of littoral animals into river much 148 difficulty, it did not occur at all in the case of the loricates, scaphopods and cephalopods, probably because they did not find the conditions of their existence there; and only a few snails and bivalve groups have succeeded in becoming fully native to freshwater. In many would be misplaced to draw conclusions on the origin of river dwellers on the basis of their present distribution; one may well assume cases that it small groups living in restricted areas, such as Clea, Scaphula, Sinomytilus, Iphigenia, Glaucomya, Tanysiphon, Novaculina, Anticorbula 1684 and Erodona, have migrated from the sea into the rivers but this cannot be assumed for the others, it, widely distributed. The New Zealand latiids emptying into some of which are related to are very the South American chilinids and indicate an earlier connection between both lands. The situation may be similar in the occurrence of Planorbula in tropical America and in African lakes (Lake Tanganyika, Lake Chad) to lower Egypt, especially because other freshwater groups are also native both continents. The eastern Asian genus Semisulcospira is related to to American Pleurocerinae. The Melantriinae inhabit the IndoAustralian region, Madagascar, the tropical parts of Africa and of America. The occurrence of Melanopsis in the Mediterranean region in the North New Caledonia and lives on Ceylon, New Zealand in Indochina is very remarkable, whereas Faunus and the Philippines; Lyogyrus is found in New Caledonia. On Opara Island, lying in the middle of the southern Pacific, a few species of the genus Potamolithus have been found, which is otherwise native to South America. All these North America and connections as well as the wide distribution of some other freshwater mollusks give proof of former connections of the continents to one another. Even on continuous land masses the river systems and freshwater more or less widely separated from one another, so that at basins are present an exchange of animals transfer of spawn by water is not possible, except for accidental If, in spite of this, the same or closely related species live in them, an earlier connection of shorter or birds, etc. longer duration must have existed, such as through a high water level, especially after extensive glaciation. A particularly striking example is provided by the distribution of the micromelaniids, which extend from the Balkan across the Caspian Sea to Lake Baikal and compel the assumption that this large area was temporarily flooded; it must, however, be emphasized that not only the micromelaniids but also other mollusks, such as the genera Benedictia and Kobeltocochlea are not of marine origin. In Lake Tanganyika, aside from genera that are undoubtedly typical freshwater inhabitants like Planorbis, Isidora, Lymnaea, Viviparus, Cleopatra, Corbicula, Pisidium, a few mutelids and unionids, there live which are called thalassoid because of a resemblance to marine forms; these have given some zoologists the occasion to assume certain snails, that this lake was earlier (in the Mesozoic) connected with the sea. More assumption has been rejected and these snails are seen as peculiarly modified descendants of freshwater groups which are native in recently, this Africa; unfortunately the relationships of all have not been sufficiently such as those of the Syrnolopsinae and the Lavigeriidae, but it not to be doubted that Neothauma stands close to Viviparus and that clarified, is the Paramelanieae have arisen from the Paludominae; it is uncertain 1685 1149 whether Bithynia multisulcata Bourguignat is Mysorella marginata, because only the shell is over 1000 lake, m deep, with somewhat related Indian the to known. The very large variable salt content (due to evaporation), has offered the animals conditions similar to those of the ocean, which seems to explain their external appearance. Within standing bodies of water there is little active dispersal most of the freshwater mollusks, because they attach their eggs bodies or they are viviparous, without forming a free-living larva, known such as that for Dreissena. capability has been achieved glochidium larvae to fishes, The most of to solid ciliated efficient dispersal by the unionids through attachment of the by means of which they can be transported over great distances. The land snails too disperse in part actively, in part passively; passively mainly through human traffic, by which some species, like Oxychilus cellarium (Muller), Opeas gracile (Hutton), Agriolimax agrestis Linne, Bradybaena similaris (Ferussac), Helix (Cryptomphalus) aspersa Muller, have been transported across various continents; etc., flooded rivers may at times contribute to the dispersal. In spite of their slowness, land snails, in the course of long periods of time, can migrate across wide stretches of land so long as they find favorable local conditions and climate, and the possibility of nourishment. But because even related groups at present live in separate parts of the world and in these parts they are more or less widely distributed and earlier split into subgroups, an connection between the land bodies must have existed. Some such connections are rather generally accepted, for example, a large continent Gondwanaland, which largest part in about the Permian included South America, the of Africa and Australia, and which to Jhering, at the time later split up; according of the Upper Cretaceous, the eastern part of South America (Archibrasil) was connected through the Archhelensis with Ethiopia (Archafrica), the western margin (Archiplata) was connected with Antarctica (Archinotis) and with a northern "Schuchertland" which corresponded to the western part of North America, whereas its eastern was connected in the north with Europe (Archiboreis). India to Madagascar formed Lemuria. It is assumed that at the time of the Eocene part a large land (Archigalenis) connected eastern Asia with the western parts of North America and the northernmost part of South America (Archiguiana). By means of these and some other intermediate lands, such as connections of islands with one another and with continents the present-day distribution of land snails and other animal groups explained. As far as the Polynesian expressed the view is islands are concerned, Pilsbry has that, at the end of the Palaeozoic or during the early Mesozoic they were connected by a large continent, which was inhabited 1686 only by some primitive land snails (including the following nonoperculate pulmonates: Achatinellacea, Vertiginacea, Succineacea, Endodontidae and Ariophantidae) and very soon largely sank some of this continent Due various the changes the surface of the earth has undergone dispersal and on the starting points any certainty identified with in the tropics. If fossil it does not live in the case of some of the oldest groups. In it probably mainly snails, littoral remains of a family were found in areas where at present, this the assumption that took place earlier or it of their development. This can hardly be general the individual groups arose from 1150 at of the land snails would have been considerately different, depending on whether later Although with South America as improbable. to the great times, into the sea. on Juan Fernandez, Pilsbry considers a connection tornatellinids live does not need to be sufficient ground for has originated there; thus some cyclophorids were native in Europe, but at present inhabit mainly Asia and have perhaps also originated there; at any Craspedopoma rate, Canary Islands in the and the Azores originated from one such European group. The genus Palaeostoa Andreae, found in the western European Tertiary, cannot be considered as the ancestor to the presently living megaspirids, but rather as a lateral branch of this family, where it which probably arose in Africa, from spread to the west (Brazil) and the east (Queenland, New Guinea), but became extinct in home. original its Related groups, and those coming from have migrated from in various directions common ancestors, may home and have their original developed differently under altered conditions. Thus, some groups are distributed mainly in the northern hemisphere, others The original center of the in development of the pulmonates the southern. may have been on the shore of the Indian Ocean, from where they migrated directions. Of the terrestrial groups the oldest are: which branched off very early from shelled 1. in all the soleoliferans, snails related to ellobiids and are closest to the littoral oncidiids; they are distributed over the equatorial palm zone. 2. the "Orthurethra" with the stirps of the Achatinellacea and first of which as well as the amastrids and partulids have mainly spread eastward, the cochlicopids, vertiginids, valloniids and enids, probably related to which are the clausiliids, have spread more Vertiginacea, the westward and northward but southward. 3. in part have also reached more or The endodontids, which whereas the related zonitids, are distributed over vitrinids, ari'onids exclusively inhabit the southern attained their main development lands. in more southward; for haplotrematids) 4. Africa. less far continents, and limacids have become native mostly in the northern hemisphere, the ariophantids the paryphantids and streptaxids (except all almost The Achatinacea, which 5. The Acavacea, which 1687 lands of the inhabit distributed mainly southern hemisphere, whereas the Helicacea are hemisphere; the bulimuldis in the northern developed from strophochilids may have South America and from there have in spread in different directions. Of the Nomenclature of the Mollusks the molluscan genera The naming of present in a thoroughly at is unsatisfactory condition, thanks to the rules of nomenclature set up a few decades ago, which prescribe the names published to the at gone unnoticed, the time of publication only one described species which can be regarded greatest if was mentioned Among these publications, the "Museum Boltenianum," published in as the genotype. damage was done by the 1798 by P.F. Roding and reprinted names erected by Bolten generic 1151 application of the law of priority strict since 1758, that in part had 1906, which contains numerous in for his collection. Whereas these names unfortunately have been accepted by most conchologists, those published in the "Museum Calonnianum" in 1797 are accepted by some, rejected by others because no author was named. The logical reason behind each naming is that with each name the same object is always designated. sight of this reason, We have apparently completely and a contest arose to replace as used names as possible by others. The result many different names have been used nomenclature requires a special study, and completely fruitless. In to the effort With such a division of opinion, which find the approval of published first recent publications of course this that basically is order to overcome this problem, application was made to allow exceptions commonly used names, an the lost customarily that for certain genera so is in many name all. in the contains typographical errors or law of priority for many of the most which nevertheless found it Some form it is little support. hardly possible to refer to names is zoologists unconditionally accept in which it is printed, even if grammatically incorrect it — which could hardly be considered science any longer. Like the "Museum Calonnianum," a few other works of the 1 8th century are accepted by some and rejected by others, because the authors did not use binary names, such as Chemnitz in the "Neucs Conchylien- Cabinet" or Geoffroy (Traite sommaire des Coquilles, Paris, 1767). for If, one accepts as the author of Ancylus not Geoffroy but then, one can regard with Beck, A. fluviatilis Muller as the instance, Miiller, Recently the attempt has been made to validate some old names, which were rather worthless because they included various genotype. groups, by designating one species as the genotype; unfortunately, 1688 because of this such monstrosities arose that for instance, Bulimus, which was generally considered a freshwater genus Bithynia. Calonnianum in the sense identical with the in the sense of Cerion, but in the for the Museum Museum Boltenianum it is as used of the small Pupilla. the typical species is at times debatable, because sometimes unclear whether a named species is now used is published in the first marine genus Solidula, and by Draparnaud The designation of it land snail genus, Pupa was actually is meant as genotype in the present-day sense, especially by older zoologists. A further difficulty consists in the fact that earlier slightly modified by certain malacologists, without creating new genera, as for instance Scalaria some names were the same time at Lamarck for Scala (Klein) Bruguiere, Nuculana Link for Nucula Lamarck, Stomax Montfort for Stomatia Helbling, Phasianus Montfort for Phasianella Lamarck, Calyptrus Montfort for Calyptraea Lamarck, Clavus Montfort for Clavatula Lamarck, Planorbarius Froriep for Planorbis Muller, If etc. thereby a species was mentioned, this cannot be considered as the genotype of the presumably new genus. The recently established name that a species identical with the genus name can only have validity typical, evidently if is to rule, be regarded as a different species was not previously designated as the genotype. Should it not be possible to put on end this chaos in nomenclature? 1152 ! Literature on Mollusks It would be understandable if the readers of this handbook wished to find, as far as possible, references to the literature for all the details, but this would go will be made on the far beyond the available space; and here only a few remarks literature on mollusks. All statements about the erection of genera, subgenera and sections are contained in the alphabetically arranged Nomenclatur Generum Animalium, which of course, has not been quite completed at the present time. Summaries of all molluscan species for the purpose of identification are impossible because of the enormous, continuously increasing number, of the latter. Such works were of course begun, but have remained incomplete, such as the second edition of the Systematisches ConchylienCabinett by Martini & Chemnitz, in which the individual groups were studied by different conchologists in the course of several decades. As some of them are already very much outdated, others but some of recent date, especially those by Kobelt, are a result of this, rather inferior, very useful. are 1689 The American Manual of Conchology begun by Tryon and continued by Pilsbry is the most consistent. Studied in are the cephalopods, the it shelled marine gastropods, the loricates (Polyplacophora), and scaphopods in Series 1. Series 2 contains only the land snails, but incomplete. The monographs of some it is so far families (bulimulids, urocoptids, achatinacens, oleacinids, achatinellaceans and vertiginaceans) the are best there are; the enids, clausilids, and a few other families, as well as the freshwater snails and all bivalves are missing. The Conchologia Iconica by Reeve contains good large volumes of most of the species known at the 20 illustrations in time it appeared in 1843—1878, and thus does not contain many species that have since been described. Innumerable special works appeared in various journals, a few of which are dedicated only to malacology, of which there are in Germany: Zeitschrift fur Malakozoologie 1844-1852; Malakozoologische Blatter 1854—1891; Jahrbucher der Deutschen malakozoologischen Gesellschaft 1874-1887 and Nachrichtsblatt of the same society since 1869, which has recently received the in title Archiv fur Molluskenkunde; France Journal de Conchyliologie since 1850; of the Malacological Society of London since Conchology since 1874; Many marine in 1 in England Proceedings 893 and The Journal of America; The Nautilus since 1889. species are described in the reports of large expeditions, such as the "Astrolabe," the "Challenger," the "Blake," the "Travailleur" and "Talisman," the Plankton Expedition (mainly cephalopods), the Deutschen Tiefsee-Expedition, the Deutschen Sudpolar-Expedition Kobelt's Iconographie der europaischen schalentragenden Conchylien has remained incomplete. Valuable is: etc. Meer- G.O. Sars, Mollusca Regionis arcticae Norvegiae, 1878. The English species are described by 1153 Forbes & Hanley (History of British Mollusca), by Jeffreys (British Conchology) and by Alder & Hancock (Monograph of the British nudibranchiate Mollusca), the French especially by Bucquoy, Dautzenberg & Dollfus (Mollusques marins du Roussillon); the Mediterranean species were summarized in the Carus, Prodromus Faunae mediterraneae, the Iberian by Hidalgo and Nobre. Turton in 1932 listed the numerous species found near Port Alfred (South Africa). Dall provided catalogs of species from the southeastern coast of the United States (1889), from Peru (1909) and the northwestern coast of America (1921). Japanese species Japonici were studied by Lischke, Dunker (Index Molluscorum Maris 1882), Pilsbry (Catalogue of the Marine Mollusks of Japan 1895) and recently by Iwakawa (1919) and Sh. Hirase (Collection of 1934), the cephalopods by M. Sasaki (1929). Robson began a monograph of cephalopods, of which so far the octopods have Japanese Shells been completed (1929 and 1932). 1690 The European land and freshwater mollusks described in are Rossmassler's Iconographie, which Kobelt continued, and in addition in several treatments of the faunas of individual countries, such as the German by Ehrmann, the English by Taylor (incomplete), etc. Kobelt in 1909 published the "Verzeichnis der aus Afrika bekannten Binnenconchylien" which however was not very complete and has since been augmented by the description of numerous species; Connolly 1912 published a list and described new African species Congo have been in of the South African land and freshwater mollusks in several studied by Pilsbry works; the species of the 1919 and 1927. Kobelt in 1879 published a "Fauna Molluscorum extramarinorum Japoniae"; Chinese species have been described mainly by Father Heude and O. v. Mollendorff, the latter also greatly contributed to the investigation of the Philippine species. Valuable is a list of the helicoid land snails of Asia by Gude (1902, 1903). Land and freshwater snails of Celebes were collected and studied by P. & F. Sarasin; the other lying further to the east to New Sunda Islands as well as the islands Guinea have recently had their mollusks thoroughly investigated by several researchers. The study of the land and freshwater mollusks of the United States by Binney and Lea has also been recently greatly supplemented and enriched with several works by Pilsbry, Baker, Walker, etc. Strebel freshwater mollusks, likewise Fischer Mexique et examined the Mexican land and & Crosse (Mission scientifique au dans l'Amerique centrale) and Martens (Biologia Centrali- Americana). Pilsbry has studied the Patagonian inland mollusks (1911). These few data may give a certain amount of information; supplemented to a certain degree genera and species are 1154 by the annual reports in it can be which new listed. Editors' note: "Corrections" on this page have been incorporated as footnotes to appropriate text throughout this translation. ^Tiliiiiiiiiiiiiiiiiiiii *39088009057605*

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Handbook of Systematic Malacology, Part 3 (Scaphopoda / Bivalvia / Cephalopoda) [Annotated English-language edition of: Thiele, J., Handbuch der systematischen Weichtierkunde, Teil 3]

Handbook of Systematic Malacology, Part 3 (Scaphopoda / Bivalvia / Cephalopoda) [Annotated English-language edition of: Thiele, J., Handbuch der systematischen Weichtierkunde, Teil 3]

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