CHIEFLY OF THE UNITED STATES. 23 



Unio curatus. pi. 7, fig. 21. 



Testa Isevi, olliptioa, subinflata, ad latere parum planulata, inaequilaterali, postice biangulata ; valvulis sub- 

 crassis, antice crassioribus ; natibus prominulis; epidermide crocea, evadiata, micante; dentibus 

 cardinalibus parviusculis, striatis, acuminatis, in utroque valvule duplicibus; lateralibus longis, 

 lamellatis subrectisque; margarita salmonia et valde iridesoente. 



Shell smooth, elliptical, somewhat inflated, somewhat flattened at the sides, 

 inequilateral, biangular behind ; valves somewhat thiclv, thicker before ; beaks 

 slighly prominent ; epidermis salFron yellow, without rays, shining; cardinal teeth 

 rather small, striate, acuminate and double in both valves; lateral teeth long, 

 lamellar and nearly straight ; nacre salmon colored and very iridescent. 

 Proc. Acad. Nat. Soi. 1863, p. 193. 



Eah. — Sugar Creek, North Carolina, C. M. Wheatley, 



Cabinet of Mr. Wheatley. 

 Diam. -9, Length 1-5, Breadth 2-9 inches. 



Shell smooth, elliptical, somewhat inflated, slightly flattened at the sides, inequi- 

 lateral, biangular behind ; substance of the shell rather thick, thicker before ; beaks 

 somewhat prominent; ligament large, thick, and light brown; epidermis safii'on 

 yellow, without rays, shining, with rather distant marks of growth ; umbonial slope 

 slightly raised and rounded ; posterior slope rather narrow, somewhat carinate, with 

 two impressed lines from the beaks to the posterior margin on each valve ; cardinal 

 teeth rather small, striate, acuminate, double in both valves; lateral teeth long, 

 lamellar and nearly straight ; anterior cicatrices distinct, large and well impressed ; 

 posterior cicatrices distinct, large and slightly impressed ; dorsal cicatrices nearly in 

 the centre of the cavity of the beaks ; cavity of the shell shallow and wide ; cavity of 

 the beaks shallow and obtusely angular ; nacre salmon color and very iridescent. 



EemarJcs. — A single specimen only is before me, and that has imperfect beaks ; 

 consequently the character of the undulations is not observable. The outline is of a 

 very regular ellipse. The nacre is of a very pale tint of salmon, but this may not be 

 universally so. I should suppose, from the general character of the epidermis and 

 the nacre, that the prevailing color would be salmon , perhaps sometimes it may be 

 found white, but I doubt if this species be found of a purple color. The single speci- 

 men which was received has no appearance of rays. In outline it is near to lamellatus, 

 (nobis,) but is not allied to that shell in its general characteristics. It properly 

 belongs to the group of which Savannaliensis may be considered the type, having a 

 saffron yellow epidermis and salmon nacre. It is nearly allied to suhfiavus, (nobis,) 

 but is wider and of a more regular ellipse. 



