350 HELICINAD.E. 



form. In coloring it is very variable. In general, it is 

 of a yellowish or brownish color, rarely simple, but 

 usually surrounded by four or five dark bands, all or 

 most of which are broken up into dots, so as also to form 

 longitudinal series ; and sometimes these coalesce, so as 

 to form longitudinal, zigzag stripes. The denticulation at 

 the suture is caused by the prolongation of two adjacent 

 bars, which return into each other ; and in the interval 

 between two denticles are about three other bars. 

 There can be little doubt that this is identical with 

 the West India shell since described under the names 

 of C. Auhereanum, and crenulatum. 



Genus HELICINA, Lamarck. 



generic characters. 



Animal terrestrial, narrow, large for the shell ; head 

 extensile ; tentacles two, slender, eyes on small tubercles 

 at their external bases ; respiratory cavity widely open 

 in front and above ; unisexual ; operculum horny, nu- 

 cleus nearly central, elements concentric, semi-lunate or 

 sub-quadrate. 



Shell small, sub-globose, pyramidal, or lenticular, im- 

 perforate ; whorls few, smooth or spirally ridged ; colors 

 green, yellow, or brown, sometimes banded with brown. 

 Aperture oblique, semilunar, outer lip semicircular ; colu- 



