Page:American Seashells (1954).djvu/380

298 Cavolina micinata Rang Uncinate Cavoline Figure 64X Worldwide, pelagic. (40° N. to 40° S.)- 6 to 7 mm. in length. Dorsal lip with a thin margin. Ventral lip not more developed than the dorsal one. Shell with distinct lateral points. Upper lip flattened posteriorly. C. iincinati^ormis Pfeffer is a synonym. Cavolina inflexa Lesueur Inflexed Cavoline Figure 641 Atlantic and Indo-Pacific. (41° N. to 42° S.). 6 to 7 mm. in length, similar to uncinata, but the upper Hp is directed straight forward, instead of flattened posteriorly; and the ventral side of the shell is weakly, instead of strongly, convex. C. labiata Orb., C. imitans Pfeffer and C. elongata Blainville are this species. Subgenus Diacria Gray 1842 Similar to Cavolina s.s., but the dorsal lip of the shell is thickened into a pad, and not thin as the true Cavoline is. Some workers use this as a genus. Cavolina trispinosa Lesueur Three-spined Cavoline Figure 641 Worldwide, pelagic. (60° N. to 41° S.). About 1 1 mm. in length. Dorsal lip thickened into a pad. Shell with a long lateral spine on each side, and a very long terminal one. Aperture scarcely discernible. Ventral side of shell very slightly convex. C. mucro- nata Q. and G., C. cuspidata Delle Chiaje and C. reeviana Dunker are this species. Very common. Cavolina quadridentata Lesueur Four-toothed Cavoline Figure 64s Worldwide, pelagic. (36° N. to 28° S.). 2 to 4 mm. in length. Dorsal lip thickened into a pad. Without promi- nent lateral spines. Aperture well-developed. Ventral side greatly inflated. Upper lip longer than the bottom one. C. inermis Gould, C. inimita Sowerby, C. intermedia Sowerby and C. costata Pfefi^er are synonyms. Quite common. Genus CitvierivLt Boas 1886 Shell cylindrical, shaped somewhat like a fat cigar. Surface smooth. A cross-section is almost circular. Behind the aperture the shell is slightly con-