338 helicidjE. 



iug about one-fourth part, and forming the superior por- 

 tion, of the outer lip. Teeth six, two on the transverse 

 margin, sharp, projecting, and toothlike ; one in the an- 

 gle between the columellar and transverse margins, 

 broad, massive, and prominent, with occasionally one or 

 more tubercles about its base ; one on the lower part of 

 the columellar margin ; two on the outer lip, in the base 

 of the aperture, and at the junction of the two curves. 

 Umbilicus rather wide. 



Length one-thirtieth, diameter one-fortieth, of an inch. 



Geographical Distribution. Inhabits Massachu- 

 setts, Connecticut, and Vermont, Oliio and Mississippi, 

 and, probably, is widely extended. 



Remarks. This is the most minute of our shells, and 

 probably of the genus ; and although so small that the 

 eye cannot, -without the aid of a microscope, detect its 

 characters, they are very strongly defined. The parts 

 about the aperture are particularly well developed, the 

 teeth being long, compressed, and sharp, and the ti'ans- 

 verse margin distinctly bounded. Prof. Adams mentions 

 that twelve matui-e specimens weighed less than six- 

 tenths of a grain. It is found under or among dead 

 leaves. It is gregarious in its habits ; when one is found, 

 many others may be quite certainly found near it. 



