UNIO TRUNCATUS. 



DESCRIPTION. 



Shell triangular, very convex, gaping a little at the 

 posterior extremity; posterior luniile distinct; anterior 

 margin very much flattened, forming a right angle with 

 the disk; disk with an indented groove on the posterior 

 side, extending from beak to base; cmterior tip truncated; 

 ligament slope slightly grooved; basal margin dilated in 

 the middle; anterior margin slightly retuse; epidermis 

 olive-yellow, radiate with green, interrupted into short 

 lines and spots generally sagittate; witJiin white or rose- 

 colour; cardinal teeth large and prominent; mnsctdar im- 

 pressions small; anterior impression oval, impressed. 



SYNONYMS. 



Unio truncata, Raf. Ann. gen. dcs Sc. Phys., vol. v. 



Poulson's translation, p. 31. 

 U. ELEGANS, Lea. Trans. Amer. Phil. Soc, new scries, 



vol. iv. p. 83, pi. ix. fig. 13. 



OBSERVATION. 



This shell inhabits the Wabash, Scioto, Ohio, and 

 other western rivers. 

 PI. G7. 



