45 



low, varied with green; two green rays behind the 

 iimbonial slope. 



OBSERVATIONS. 



The only specimen of this shell Avhich I have seen, 

 is in the cabinet of the Academy of Natural Sciences, 

 where it was placed by Mr. Schoolcraft, who found 

 it in Fox river of Green Bay. It cannot be confound- 

 ed with any known species of Unio. On the posterior 

 side some small tubercles are disposed in a line, and 

 one or two others are observable on the umbonial 

 slope. 



UNIO INFUCATUS. 



Plate III.— M^. 2. 



DESCRIPTION. 



Shell short oval, compressed, posterior margin 

 wide, slightly oblique, obtusely rounded or subangu- 

 lated at the extremity; umbones wide, not prominent, 

 beaks greatly eroded; umbonial slope subangulated. 

 hardly curved; epidermis black; within pearly white; 

 cardinal teeth direct, pyramidal. 



OBSERVATIONS. 



This shell presents nothing remarkable in its ap- 

 pearance, but its oval figure and compressed sides 

 will distinguish it from the ahied species; U. hrviga- 



