NATURAL SCIENCES OP PHILADELPHIA. 31 



PACHYTOMA, Swaiuson. 

 P. tertiana, Conrad, PI. I., fig. 11. 



Pyrainidamical, volutions 5, flattened or concave laterallv. cari- 

 nated at the suture and profoundly so at the sharp angle of the 

 base ; base slightly convex, subumbilicated, subcarinated behind 

 the depression ; basal margin slightly emargiaate. 



A few specimens were found in the detritis. It is with some 

 doubt I refer it to Pachytoma, but I cannot compare it with any 

 other genus known to me. 



TOXOSOMA, Conrad. 



Conical, polished, the aperture projecting, subovate, direct, peri- 

 tome continuous ; columella concave with a plait or tooth in the 

 middle, not oblique ; base rounded, subumbilicated. 



T. eborea, Conrad, PI. I., fig. 7. 



Small, volutions 5, rounded; aperture angular above ; last volu- 

 tion expanded ; columellar tooth minute. 



Found iu company with the preceding shell. It is probably a 

 laud shell. 



CIRROBASIS, Conrad. 



Subcylindrical, with last volution free, aperture projecting, 

 peristome continuous, mouth narrow, subovate, oblique. 



C. venusta, Conrad, PI. I., fig. 15. 



Elongated, volutions 9, very slightly convex, the last volution 

 straight on the side; a few volutions near the apex with a cari- 

 nated line below the middle of each volution ; angle of base sub- 

 carinated. 



Only one specimen was found, and that in perfect preservation. 

 The genus is probably terrestrial, allied to Cylindrella. 



LIOSOMA, Conrad. 



Conical, polished ; aperture subelliptical ; columella with one 

 plait in the middle ; base entire. 



L. curta, Conrad, PI. I., fig. 8. 



Volutions smooth, 4, slightly convex; columella conspicuously 

 cut or indented above the plait, which is not oblique. 



