202 NEW UNIONIDiE OF THE 



jj a i, % — Davidson County, North Carolina, Dr. Genth. 



My cabinet. 

 Diam. -8, Length 1-3, Breadth 2-4 inches. 



Shell smooth, subtriangular, flattened at the sides, very inequilateral, subbiangular 

 behind, round before ; substance of the shell somewhat thick, slightly thicker before ; 

 beaks slightly prominent ; ligament rather short, thick and dark brown ; epidermis 

 dark brown, nearly black, without rays, with indistinct rather distant lines of growth, 

 striate on the lower portion ; umbonial slope raised and obtusely angular ; posterior 

 slope slightly flattened, with an obscure wide furrow from the beaks to the margin 

 on each valve ; cardinal teeth small, sulcate, crenulate, subcorneal and double in 

 both valves ; lateral teeth long, lamellar, corrugate and somewhat curved ; anterior 

 cicatrices distinct, rather large and well impressed ; posterior cicatrices confluent, 

 large and slightly impressed ; dorsal cicatrices placed above the centre of the cavity 

 of the shell ; cavity of the shell rather deep and wide ; cavity of the beaks shallow 

 and rounded ; nacre whitish and iridescent. 



Remarks. — A single specimen only is before me. This species belongs to the com- 

 planatus group, and is, perhaps, nearest to fumatus, (nobis,) but is not so raised on 

 the posterior slope. It reminds one of a young crassidens, Lam., but the teeth are 

 by no means so large. The beaks" being eroded, it could not be ascertained if the 

 tips are undulate. The nacre of this specimen is whitish, with clouded epidermal 

 matter. Other specimens may prove to be purple and salmon. 



Unio macer. PI. 29, fig. 271. 



Testa leevi, oblonga, conrpressissima, valde insequilaterali, postice subbiangulata ; valvulis tenuibus ; 

 natibus parvis, acuminatis, ad apices undulatis ; epidemiide fusca, nitida, valde radiata ; dentibus 

 cardinalibus parvis, tuberculatis ; lateralibus prselongis, attenuates, lamellatis subrectisque ; marga- 

 rita pm - purea et iridescente. 



Shell smooth, oblong, very much compressed, very inequilateral, subbiangular 

 behind ; valves thin ; beaks small, acuminate and undulate at the tips ; epidermis 

 brown, shining, very much rayed ; cardinal teeth small, tuberculate ; lateral teeth 

 very long, attenuate, lamellar and nearly straight ; nacre purple and iridescent. 

 Proc. Acad. Nat. Sci., 1857, p. 86. 



Eab. — Roanoke Eiver, Weldon North Carolina, Prof. Emmons. 



My cabinet and cabinet of Prof. Emmons. 

 Diam. -6, Length 1-4, Breadth 2-8 inches. 



Shell smooth, oblong, very much compressed, very inequilateral, subbiangular 

 behind and obliquely rounded before ; substance of the shell thin, somewhat thicker 

 before ; beaks small, acuminate and transversely undulate at the tips ; ligament 

 rather thin, long and dark brown ; epidermis brown, shining, very much rayed, 



