OP CONCHOLOGY. 57 



3. Stenotrema hirsuta, Say. 



Plate 9, figure 24. 



Shell subglobose, hairj ; spire convex, elevated, suture deep ; 

 whorls 5, well rounded, periphery subangulate, shell very convex 

 below, umbilicus covered ; aperture narrowly transverse, nearly 

 closed by the lamelliform parietal tooth, the outer lip with a tri- 

 angular notch upon its basal portion. 



Diam. 6, height 4 mill. 



New England, Middle and Western States. 



The following are the chief differences between this species 

 and the preceding : — Hhsuta is smaller, more globose, its 

 parietal tooth somewhat sinuous, and terminating abruptly, and 

 the lip notch larger proportionally. *S'. stenotrema has a smaller 

 and more central lip notch, and its large parietal tooth is regu- 

 larly bow-shaped over its edge, instead of being sinuous and ab- 

 ruptly terminated. The species are both of them widely dis- 

 tributed, but the range of hirsuta is far greater than that of 

 stenotrema. 



XX Outer lip not incised in the middle. 

 4. Stenotrema maxillata, Gould. 



Plate 9, figures 31, 35. 



Shell small, globose ; spire conical, convex, suture well im- 

 pressed, subangular on the periphery, and more convex below ; 

 whorls 5, narrow ; aperture transverse, nearly filled by a long 

 lamellar parietal tooth, lip closely appressed, narrow, with a 

 lamina behind its margin, and scarcely visible on account of the 

 parietal tooth being in front of it ; this lamina tapers out to the 

 margin of the lip at its superior termination ; umbilicus covered. 

 Light chestnut color. 



Diam. 6, height 4 mill. 



Tennessee, Chattahoochee River, Georgia, 



Readily distinguished from hirsuta by its entire lip and the 

 raised lamellar tooth behind it. 



