CHIEFLY OF THE UNITED STATES. 301 



Unio hu.merosus. PL 45, fig. 113. 



Testa laevi, elliptico-oblonga, compressa, ad latere planulata, inEequilaterali, postice obtuse biangulari, 

 antice rotunda; valvulis subcrassis, antice crassioribus ; natibus prominulis; epidermide rufo- 

 fusca, obsolete radiata ; dentibus cardinalibus grandibus, sulcatis, partitis ; lateralibus pra;lono-is, 

 lamellatis corrugatisque; margarita salmonis colore tiiicta et valde iridescente. 



Shell smooth, elliptical oblong, compressed, flattened at the side, inequilateral, 

 obtusely biangular behind and round before; valves rather thick, thicker before; 

 epidermis reddish-brown, obsoletely radiated; cardinal teeth large, sulcate and 

 divided; lateral teeth very long, lamellar and corrugate; nacre salmon color and 

 very iridescent. 



Proc. Acad. Xat. Sci. 1868, p. 161. 



fla&.— Charlotte, Mecklenberg Co., N. C, C. M. Wheatley. 



My cabinet and cabinet of Mr. Wheatley. 

 Diam. !•], Length 21, Breadth 3.5 inches. 



Shell smooth, elliptical oblong, compressed, flattened at the side, inequilateral, 

 obtusely biangular behind and round before ; substance of the shell thick, thicker 

 before; ligament long, large and dark brown; epidermis reddish-brown, obscurely 

 radiated, with somewhat distant marks of growth ; umbonial slope flattened and 

 rounded ; posterior slope narrow-elliptical, carinate, dark brown, with two impressed 

 lines in each valve; cardinal teeth large, suleate and divided j lateral teeth very 

 long, lamellar and corrugate; anterior cicatrices distinct, very large and very much 

 impressed; posterior cicatrices confluent, large and slightly impressed; dorsal 

 cicatrices placed above the cavity of the beaks; cavity of tlie shell shallow and wide ; 

 cavity of the beaks very shallow and rounded ; nacre salmon colored and very 

 iridescent. 



Remarhs. — In outline this species is very nearly the same as Charlottensis (nobis), 

 but that is a thinner shell, with very different cardinal and lateral teeth, which are 

 very small, while in humerosus they are thick and almost massive. The cavity of the 

 shell in the latter is also much more shallow. The color of the nacre is also different. 

 The cardinal teeth of Jiumewsus are remarkably sulcate, and disposed to be divided into 

 three parts in each valve. The lateral teeth are large and stout. The whole of the 

 posterior slope is dark, and there are a few thin rays before the umbonial slope. In 

 a younger specimen the rays are over the whole disk. In some respects this species 

 reminds one of Weldonensls (nobis), but humerosus is more quadrate, has larger teeth, 

 and the color is salmon. 



