40 



behind which is another obscure angle, passing from 

 the beaks to the extremity, which is subtruncated; 

 cardinal teeth erect, oblique, compressed; within yel- 

 lowish or pale purple. 



OBSERVATIONS. 



This shell resembles U. purpureus in outline, bur 

 it is much more convex, and the pecuhar biangular 

 ])osterior side will distinguish it from that species. 

 Some specimens are rayed, and old individuals be- 

 come very ventricose. One of these has a yellow 

 epidermis, but the usual colour is olivaceous. 



Inhabits the Water ee canal, South Carolina,wliere 

 it was first discovered by Dr. 13 landing. I have 

 since found it in the small creeks, near Cooper river. 

 S. C. 



I have dedicated it to my friend, Professor Edmund 

 Ravenel of Charleston, through whose polite atten- 

 tion I was enabled to make a valuable collection of 

 iresh water shells and organic remains in an inte- 

 resting portion of South Carolina. 



In my excursions in the vicinity of the Santee canal. 

 I found a few shells of this species, and the following 

 also occurred in the same waters: U. nasutus, Santee 

 canal; U. angustatiis, Lea, U. ochraceus, ? Say, U. 

 congarceus, Lea, U.delumhis, nob. and a shell which 

 is probably a variety of U. purpureus, Say. 



