NEW FRESH WATER AND LAND SHELLS. 195 



The rays are so numerous in some specimens as to give a dark green hue to 

 the whole disk, except at the anterior margin, where it is always more or less 

 yellow. The umbonial slope is elevated, and in some individuals disposed to 

 be tuberculate. 



Unio Stonensis. Plate 8, Fig. 5. 



Testa ellipticd, valde compressd,planulatd,valdein(Bquilaterali; valvulis eras sis; natihus prominulis, 

 ad apices undulatis; epidermide luteo-fuscd; dentibus cardinalibus parvis; lateralibus longis, crassis 

 curvisque ; margarita saLmonis colore tinctd et iridescente. 



Shell oval, very much compressed, flat-sided, very inequilateral ; valves thick ; beaks slightly prominent, 

 undulated at the tip; epidermis yellowish-brown ; cardinal teeth small; lateral teeth long, thick and curved; 

 nacre salmon-coloured and iridescent. 



Hab. Stone's River, Tenn. S. M. Edgar. 



My Cabinet. 

 Diam. .1, Length 1.9, Breadth. 3.3 inches. 



Shell oval, very much compressed, flat-sided, very inequilateral; biangular 

 behind ; substance of the shell thick ; beaks slightly prominent and minutely 

 undulate at tip; ligament long and thick; epidermis yellowish-brown, roughly 

 striate; cardinal teeth small, striate, lobed; lateral teeth long, curved and thick; 

 anterior cicatrices distinct; posterior cicatrices confluent; dorsal cicatrices 

 placed in a row behind the cardinal tooth; cavity of the shell very shallow; 

 cavity of the beaks scarcely perceptible ; nacre salmon-coloured and iridescent. 



Remarks. — This fine shell seems to be pretty closely allied to U. gihhosus, 

 Barnes. It is, however, a less transverse species, more compressed and more equi- 

 lateral. The nacre is very fine and in this specimen salmon-coloured, — this tint 

 may not prove to be permanent. Having but a single specimen before me, I 

 am unable to say whether it occurs rayed. This individual is entirely without 

 rays. The transverse strise are rough. 



Unio Lesueurianus. Plate 8, Fig. 6. 



Testd subrotundd, subinflatd; valvulis crassis; natibus prominentibus ; epidermide fused, striata, 

 radios maculatos habente; dentibus cardinalibus subgrandibus ; lateralibus parvis rectisque; margarita 

 albd et iridescente- 



VIII. — 2 z 



