298 American Seashelh 



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- 



