73 



The two fine specimens figured belong to the 

 splendid collection of Mr. Poulson. They were sent 

 from Nashville, Tennessee. 



UNIO SUBPLANUS. 



Plate XLL— Fig. 1. 

 DESCRIPTION. 



Shell sub-oval; disks flattened; anterior margin 

 regularly rounded, obliquely descending; umbonial 

 slope rounded; posterior slope dilated; beaks not pro- 

 minent, distant from the anterior extremity; ligament 

 margin elevated, slightly oblique; posterior extremity 

 truncated; epidermis yellowish-brown, with numerous 

 fine concentric wrinkled lines; within pale rose colour; 

 cardinal teeth oblique; lateral teeth rectilinear. 



Cab. A. N. S. No. 20412. 



OBSERVATIONS. 



I have recently received several specimens of this 

 shell from Lexington, Rockbridge county, Virginia, 

 where they were found by Mr. Newkirk in a branch 

 of the James river. Approaches U. Masoni, but is 

 more compressed and elongated, and cannot be con- 

 founded with it. 



