Diagnosis. Shell with high spire and deep suture, lacking a basal disk. Axial sculpture of thin, projecting costae, spiral sculpture lacking or of fine striae.
Remarks. DuShane (1979) placed species with rounded whorls and no spiral sculpture in Nitidscala DeBoury, 1909 (type species Scalaria unifasciata G. B. Sowerby II, West Indies), which differs from the type species of Epitonium only in its more slender profile. Those with fine spiral sculpture were placed in Asperiscala DeBoury, 1909 (type species Scalaria bellastriata Carpenter, 1864, California). Authors prior to DuShane (1979) had used these taxa at the subgeneric level. In treating the North Atlantic species, Bouchet and Warén (1986) ignored all subgenera and placed all species with rounded whorls, varying expression of spiral sculpture and lacking a basal disk in Epitonium. Here I return the northeastern Pacific species to Epitonium, mentioning the appropriate subgenus in the remarks under each species.
This treatment of the offshore species of Epitonium includes all that are known from southern California. DuShane (1979) did a monumental job of reducing the excessive number of unillustrated taxa described by Dall in his declining years. Revisions to the synonymy of two of the species treated by DuShane (E. berryi and E. sawinae) are made here.