48 



if so, we arc unacquainted with the male personatus. 

 The exterior somewhat resembles V. Icevigatus, and 

 the cardinal teeth are very like those of U. nexus; 

 Say's description applies only to the immature shell. 

 For the use of the splendid specimen here represented 

 and described, we are indebted to G. W. Feather- 

 stonhaugh, Esq., who procured it from Cumberland 

 river, Tennessee. Mr. Say's specimens were from 

 the Wabash. 



UNIO CORDATUS. 



Plate XXV. 



DESCRIPTION. 



Shell subtriangular, not oblique, length and height 

 nearly equal; beaks distant from the anterior margin, 

 prominent, incurved and pointed; anterior lunule very 

 broad and obtusely obovate, beneath which is a flat- 

 tened cordate space with the opposite margin recti- 

 linear; inferior portion of the anterior margin regu- 

 larly rounded to the middle of the basal margin, 

 which is emarginate and ascending posteriorly; sinus 

 of the posterior side not oblique, slightly arcuate; 

 posterior margin rounded above, angulated at its 

 junction with the basal margin; epidermis fuscous, 

 with green interrupted rays over the umbo; within 

 white. 



SYNONYME. 



U. cordatus, Raf. Ann. gen. ties Sc. Phys. vol. v. p. 46. Poul- 



son's trans, p. 52. 

 Cab. A. N. & No. 2018. 



