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 27. purpureus in outline, but 
it is much more convex, and the peculiar biangular 
posterior 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/where 
it was first discovered by Dr. Blanding. 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 
freshwater 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: 27. nasutus , Santee 
canal; 27. angustatus, Lea, 27. ochraceus, ? Say, 27. 
congarceus, Lea, U.delumbis, nob. and a shell which 
is probably a variety of 27. purpureus , Say. 
