40 PHYSA MICROSTOMA. 



DESCRIPTION. 



SHELL elliptic, composed of four flattened 

 whirls, separated by a distinct but very shallow 

 suture: substance of the shell thick: spire 

 shorter than the aperture, and ending in a point: 

 aperture narrow elliptic, with a continuous peri- 

 treme, and the labium much thickened anterior- 

 ly: columella with two nacreous elevations, or 

 obtuse teeth. 



COLOR light brownish-ochraceous: columella 

 and external periodical (varicose) bands, wldte, 

 whilst the corresponding internal bands are 

 chesnut. 



GEOGRAPHICAL DISTRIBUTION. Kentucky and 

 Ohio. 



OBSERVATIONS. 



This is a remarkable shell, and readily dis- 

 tinguished from all the American species of 

 Physa, hitherto described, by the teeth upon 

 the columella. 



