[73] 



******* Shell small, depressed ami rihhed-striate above, 

 many-whorled ; periphery generally carinate ; convex 

 beneath, showing several whorls; aperture with- a 

 V-shaped parietal tooth. 



t Aperture tridentate, base exhibiting one and a half to two 

 whorls. 



8. D^DALOCHiLA, Beck. Shell small, depressed, ribbed- 



striate, periphery angulate, below convex, sho\ving more- 

 than one, sometimes nearly two, whorls, with a minute 

 central perforation ; lip auricular, frequently expanded,, 

 the place of the teeth being marked externally by scro- 

 biculations ; parietal tooth V-shaped, joined by a raised 

 callus with the extremities of the lip. 



Southern States, Mexico, Guatemala, Cuba, &c. 



f Shell planorboid, many-whorled ; aperture with a V- 

 shaped tooth, but no lip teeth. 



9. PoLYGRA, Say. Shell planorboid, many-whorled, whorls 



narrow, ribbed above, periphery angulate ; aperture 

 small, subtrigonal, with a V-shaped parietal tooth, joined 

 by a raised callus to the extremities of the lip ; below 

 plane, showing several whorls, with a narrow umbilicus.. 

 Horn color. 



Gulf States and West Indies, also South America. 



VALLONIA, Risso. 

 1. Vallonia minuta, Say. 



Plate 7, figure 2. 



Spire depressed, convex, whorls four, the last rapidly increas- 

 ing and spreading at the mouth ; thin, transparent, very min- 

 utely striated, or sometimes distantly costatc ; aperture orbicu- 

 lar, lip large, well rounded ; umbilicus large. Light horn color;, 

 with generally a greenish tinge, lip white. 



Diam. 2-5 mill. 



Maine to South Carolina, and westward to the Rocky Moun- 

 tains. 



This species was described many years ago by Mr. Say,, and 

 his species has since been recognized as distinct by several con- 



