NEW FRESH WATER AJND LAND SHELLS. , 211 



Re?narks. — This is a very interesting species, and so closely resembles the 

 U. Metanever, Raf. on one side, and U. intermedius, Gon. on the other, that I at 

 first, on seeing a single specimen, had doubts of the propriety of proposing for it 

 a new name. I have before me five individuals brought by Mr. Edgar from 

 Middle Tennessee, and also five specimens of U. intermedius which came from 

 East Tennessee. The latter are all smaller than the tuberosus, and differ in 

 having very few and very small tubercles, while the tuberosus is crowded with 

 large ones. From the metanever it differs totally, in being without the large 

 and regular tubercles of the umbonial slope, and the slope is less elevated. The 

 nacre is very silvery, and with little or no iridescence. In one specimen there 

 are a few indistinct green spots in the epidermis, which in fine young speci- 

 mens may resemble the arrow-headed marks of the metanever. 



Unio plenus. Plate 14, Fig. 26. 



Testa triangulari, inflata; valvulis crassissimis ; natihus elevatis, crassis; epidermide luteo-fuscd, 

 rugosa; dentibus cardinalibus magnis; lateralibus hrevibus subrectisque ; margaritd alba et iridescente. 



Shell triangular, inflated; valves very thick; beaks elevated and thick; epidermis yellowish-brown, 

 v?rinkled; cardinal teeth large; lateral teeth short and nearly straight; nacre wiiite and iridescent. 



Hab. Ohio River, near Cincinnati. T. G. Lea. 



My Cabinet and Cabinet of T. G. Lea. 

 Diam. 1.1, Length 1.8, Breadth 1.6 inches. 



Shell triangular, inflated, flattened before the umbonial slope, nearly equila- 

 teral, emarginate at base; substance of the shell very thick; beaks elevated, 

 very thick and incurved, at the tip slightly undulate; ligament very short and 

 rather thick; epidermis yellowish-brown, wrinkled, obscurely radiated on the 

 umbones, the rays being lost in the wrinkles nearly half-way from the beaks; 

 umbonial slope carinate; posterior slope much flattened; cardinal teeth large, 

 single in the left and double in the right valve; lateral teeth short, nearly 

 straight and disposed to be double in both valves; anterior cicatrices distinct; 

 posterior cicatrices distinct, the smaller one being placed on the end of the 

 lateral tooth; dorsal cicatrices placed on the under side of the cardinal tooth; 

 cavity of the shell rather deep; cavity of the beaks deep and angular; nacre 

 white and iridescent. 

 VIII. — 3 D 



