46 
tus, Rar. has most resemblance to it in habit. With 
age the posterior extremity becomes slightly pro- 
duced. 
Inhabits Flint river in Georgia. 
UNIO OVIFORMIS. 
Puate II.—Fig. 6. 
. : DESCRIPTION. 
Shell ovate, convex, thick anteriorly, thinner pos- 
teriorly; anterior margin rather obliquely rounded; 
posterior margin obliquely truncated; extremity an- 
gulated; beaks prominent, not decorticated, with 
three or four strong interrupted undulations; lunule 
ovate; umbonial slope rounded; epidermis light yel- 
lowish olive, with broad crowded green rays, widely 
interrupted; cardinal teeth direct; within pearly 
white, highly iridescent posteriorly. 
OBSERVATIONS. 
A beautiful species, allied to U. scalenius, Rar. 
It differs in not being sinuous or compressed; and in 
having undulated beaks. It is not oblique. 
It inhabits rivers in Tennessee, but I know not the 
exact locality. It was presented to me some years 
since by Mr. Brewster, of Mount Pleasant, Ten- 
nessee, to whom I am indebted for the finest speci- 
mens of certain species which have reached our cabi- 
nets. . 

