45 
low, varied with green; two green rays behind the 
umbonial slope. 
OBSERVATIONS. 
The only specimen of this shell which 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 w T ith 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.— Fig. 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 allied species; U. Iceviga - 
