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298 American Seashelh
Cavolina micinata Rang Uncinate Cavoline
Worldwide, pelagic. (40° N. to 40° S.)-
Figure 64X
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
Atlantic and Indo-Pacific. (41° N. to 42° S.).
Figure 641
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
Worldwide, pelagic. (60° N. to 41° S.).
Figure 641
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
Worldwide, pelagic. (36° N. to 28° S.).
Figure 64s
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-