NEW FRESH WATER AND LAND SHELLS. 205 



Shell obovate, inflated; valves thin; beaks scarcely prominent, at the tips undulated; epidermis yellow, 

 thickly rayed; cardinal teeth compressed; lateral teeth small; nacre white and iridescent. 



I-Iab. Stone's River, Tenn. S. M. Edgar. 



My Cabinet, and Cabinet of Mr. Edgar. 

 Diam. .5, Length .7, Breadth 1 inch. 



Shell obovate, inflated; substance of the shell thin ; beaks scarcely prominent, 

 with minute undulations at the tip; ligament very small and thin; epidermis 

 yellow, with numerous capillary rays over nearly the whole disk; cardinal 

 teeth compressed; lateral teeth small and nearly straight; anterior cicatrices 

 distinct; posterior cicatrices confluent; dorsal cicatrices placed on the under 

 side of the plate between the cardinal and lateral teeth; cavity of the shell deep 

 and rounded; cavity of the beaks rather deep and angular; nacre white and 

 iridescent. 



Remarks. — One perfect individual and an odd valve were all which were 

 taken by Mr. Edgar. Both these specimens are evidently females having the 

 umbonial slope enlarged, and the dentate margin which so well characterizes 

 the sex. These specimens may not be of full growth, but I doubt if they occur 

 much larger. This species has some resemblance to a young U. brevide7is, 

 (nobis,) but is a very much smaller and thinner shell, and differs in the rays. 



Unio nitens. Plate 12, Fig. 19. 



Testa ellipticd, transversa, subinflatd; valvulis suhtenuibus ; natihus subprominentibus ; epidermide 

 tenebroso-fuscd ; dentibus cardinalibus parvis, elevatis; later alibus longis subrectisque ; margarita cu- 

 pred, splendidissimd et iridescente. 



Shell elliptical, wide, somewhat inflated; valves rather thin; beaks somewhat prominent; epidermis dark 

 brown; cardinal teeth small, erect; lateral teeth long and nearly straight; nacre copper-coloured, very 

 splendid and iridescent. 



Hab. Long Creek, Cocke Co., Tenn. S. M. Edgar. 

 My Cabinet, and Cabinets of Mr. Edgar, Dr. R. O. Currey and Prof. Troost. 

 Diam. .7, Length 1.2, Breadth 1.9 inches. 



Shell elliptical, transverse, somewhat' inflated, substance of the shell thin, 

 thicker before; beaks rather prominent and slightly undulate at tip; ligament 



