UNIO FASCIATUS. 



Plate I. 



DESCRIPTION. 



Shell elliptical, compressed, yellowish olive, with 

 broad dark green rays, and a few intermediate nar- 

 row rays; umbo slightly compressed, little promi- 

 nent; anterior side short; ligament margin scarcely 

 curved, slightly declining; posterior margin obliquely 

 truncated; umbonial slope abruptly rounded; submar- 

 gin slightly furrowed; basal margin protruding a 

 little near and behind the middle; within white; 

 cardinal teeth thick, direct; margin thin, showing the 

 exterior rays. 



SYNONYMES. 



U. fasciatus, Raf. Ann. gen. des Sc. Phys. vol. v. p. 28. 



Poulson's translation, p. 20. Say, Amer. Conch. No. 6. 



Ferussac, Mag. de Zool. 

 U. carinatus, Barnes. Silliman's Journal, vol. vi. p. 126. 

 Cab. Jl. N. S. No. 1020. 



OBSERVATIONS. 



This shell has been considered a variety of cario- 

 sus by some conchologists, but it is invariably more 

 ponderous and compressed, with very different mark- 

 ings and cardinal teeth. It is most nearly related to 

 the crassus, Say, but can be distinguished by its 

 more elliptical outline, much broader and darker rays, 

 and by the beaks being less nearly terminal. Fe- 

 russac gives carinatus, Barnes, as a synonyme to 

 crassus, Say. Common in the western waters. The 



