58 



a broad high wing posteriorly, and connate in both; 

 posterior margin of the wing arcuate, and slightly 

 emarginate or angulated at base; beaks slightly pro- 

 minent; cardinal teeth single in both valves, and 

 lamelliform; lateral teeth arcuate, prominent towards 

 the extremity; nacre purple. 



SYNONYMES. 



Symphynota inflata, Lea. Trans, Amer. Phil. Soc. , new series, 



vol. iv. p. 99, pi. xiv. fig. 28. 

 U. Alabamensis, Nob. New Fresh Water Shells, p. 67. 

 Cab. Ji. N. S. No. 20405. 



OBSERVATIONS. 



Differs from U. (Symphynota) lavissimus in the 

 inflated umbonial slope and more elevated wing. It 

 was discovered near Claiborne, Alabama, by Judge 

 Tait, and sent to Mr. Lea. I have since found it 

 very abundantly a few miles south of Claiborne, but 

 it is rare in the upper part of the Alabama and in the 

 Black Warrior rivers, and has not hitherto been found 

 elsewhere. 



UNIO LEPTODON. 



Plate XXXIII. 

 DESCRIPTION. 



Shell narrow-elliptical, very thin and fragile, com- 

 pressed anteriorly, and slightly inflated over the um- 

 bonial slope; beaks very small, approximate; posterior 



