CHAPTER VII 



Periwinkles 

 Conchs and Other Snails 



Class GASTROPODA 



Subclass PROSOBRANCHIA Order ARCHAEOGASTROPODA 



Superjamily PLEUROTOMARIACEA 



Family SCISSURELLIDAE 



Genus Scissurella Orbigny 1823 



Subgenus Schizotrochus Monterosato 1884 



Scissurella crispata Fleming Crispate Slit-shell 



Massachusetts to eastern Florida and the West Indies. Europe. 



3.5 mm. (Vs inch) in width and 3.0 mm. in length. 4 to 5 whorls. Fragile, 

 frosty-white in color and sculptured by very delicate reticulations. Umbihcus 

 small, round and very deep. Periphery of whorls angulate and with two 

 thin, sharp spiral lamellae. Between these there is an open 

 slit running from the edge of the thin apertural lip back 

 about % of a whorl. Uncommon from 60 to 500 fathoms. 



The Florida Slit-shell, 5. proxivm Dall (fig. 29), from 

 South Carolina to the Lower Florida Keys, differs in being 

 half as large, with a more rounded periphery, and a higher 

 spire, so that the length is about equal to the width of the 

 shell, and in having a weaker pair of peripheral lamellae. 

 Uncommon from 20 to 434 fathoms. 



Fajnily PLEUROTOMARIIDAE 

 Genus Perotrochus P. Fischer 1885 



Perotrochus quo y anus Fischer and Bernardi 



Quoy's Pleurotomaria 

 91 



Figure 29. 

 Florida Slit- 

 shell, Scissurella 

 proxi?77a Dall, 

 YiQ inch (Massa- 

 chusetts to Flor- 

 ida, 20 to 430 

 fathoms). 



