
44 
nent, not nearly terminal; posterior margin obliquely 
truncated; umbonial slope rounded; base arcuated; 
epidermis olivaceous, obscurely rayed, wrinkled on. 
the margins; cardinal and lateral teeth very promi- 
nent, granulated; nacre whitish and iridescent on 
the posterior margin, 
Variety A. Epidermis reddish brown; nacre rose 
coloured. 
OBSERVATIONS. 
I found a very few specimens of this shell at Clai- 
borne, on the Alabama river; it is allied to U. multi- 
radiatus, Lea, but on comparing it with specimens 
of that species in Mr. Poulson’s cabinet, I found it 
sufficiently distinct; the nacre is denser, and thicken- 
ed on the margin; and the rays are of nearly uniform 
size, distant and obscure. The lateral teeth closely 
resemble those of U. multiradiatus. 
UNIO PRASINUS. 
Prats IIll.—Fig. 1. 
DESCRIPTION. 
Shell suborbicular, compressed, with distant con- 
centric Impressed lines; anterior margin obtusely 
rounded; posterior margin wide, truncated, not 
oblique; basal margin straight, parallel with the liga- 
ment margin; beaks prominent; epidermis olive yel- 

