246 



HELICID^. 



perforated by a small, deep umbilicus. Aperture nearly 

 circular, interrupted for a short space by the penultimate 

 whorl; lip simple, slightly expanded, and at the colu- 

 mellar region decidedly reflexed. 



Diameter one-eighth, axis one-tenth of an inch. 



Geographical Distribution. Inhabits Florida, and 

 is also common in the neighboring part of Cuba. 



Remarks. There are grounds for the behef that the 

 original H. egena of Say was the depressed form of what 

 is now regarded as H. chersina, while the latter name 

 was applied by him to the elevated variety. As we 

 regard both forms as varieties of the same species, and 

 as the name chersina universally obtains for it, we have 

 concluded to adopt it, and to attach the other name to 

 this very nearly allied Florida species. It is a coarser 

 and more sohd shell, with a more depressed form, fewer 

 whorls, and a decided umbilical perforation. It is rather 

 opaque, and has a pale brown color, instead of being 

 delicate and horn-colored. It must be very similar to S. 

 BootJiiana, Pfeiifcr, from Cuba. — [g.] 



