286 GENUS PLANORBIS. (June, 



Genus PLANORBIS. 



Shell discoidal; spire depressed, or concave; aper- 

 ture oblique, rounded, broader than long, visible from 

 above, and emarginated by the convexity of the penulti- 

 mate whorl; lips not reflected; whorls lateral. 



Animal aquatic, with two filiform tentacula, hav- 

 ing the eyes placed at the inner base; operculutn none. 



SPECIES. 



P. ^glabratus. Shell sinistral; whorls about five, gla- 

 brous or obsolete iy rugose, polished, destitute of any 

 appearance of carina; spire perfectly regular, a little con- 

 cave; umbilicus large, regularly and deeply concave, ex- 

 hibiting all the volutions to the summit; aperture de- 

 clining, remarkably oblique with respect to the transverse 

 diameter. 



Breadth nearly nine-tenths of an inch. 



Inhabits South Carolina. 



Cabinet of the Academy. 



Presented to the Academy by Mr. L-Hermenier of 

 Charleston, an intelligent and zealous naturalist; he as- 

 sured me that this species inhabits near Charleston. It 

 somewhat resembles large specimens of the P. trivolvis of 

 the American edition of Nicholson'^s Encyc, but differs 

 in the total absence of carina, and in having a more 

 smooth and polished surface, as well as a declining and 

 more oblique aperture, ^id a more profound and much 

 more regularly concave umbilicus. 



Genus SUCCINEA. 



Shell oval; aperture oval, much dilated, longer than 

 broad, entire; outer lip not reflected; columella almost 

 concave, edge acute; umbilicus none. 



