NEW UNIONIDiE OF THE UNITED STATES. 59 



Unio percoarctatcs, PI. 3. fig. 206. 



Testa laevi, quadrata, valde coarctata, ad latere planulata, postice subbiangulata ; valde infequilaterali ; 

 valvulis tenuibus; natibus vix proniinentibus, ad apices UDdulatis ; epklermiile tenebroso-fusca, minute 

 et valde striata; dentibus cardinalibus parvis, striatis, in utroque valvulo .duplicibus ; lateralibu? pro3- 

 longis, bimellatis rectisque; margarica purpurea et valde 1 iridescente. 



Shell smooth, quadrate, very much compressed, flattened at the sides, subbiangular 

 behind, very insequilateral ; valves thin; beaks scarcely prominent, undulate at the 

 tips ; epidermis dark brown, much and finely striate ; cardinal teeth small, striate, 

 double in both valves; lateral teeth very long, lamellar and straight; nacre purple 



and very iridescent. 



Proo. Acad. Nat. Sci. 1857, p. 85. 



Jlab. — Catawba River, Gaston Co., N. C. C. M. Wheatley and Dr. Genth. 



My cabinet and cabinet of Mr. Wheatley and Dr. Genth. 

 Diana. -8, Length 1-8, • Breadth 37 inches. 



Shell smooth, quadrate, very much compressed, flattened at the sides, subbiangu- 

 lar behind ; substance of the shell thin, slightly thickened before ; beaks scarcely 

 prominent, undulate at the tips ; ligament long, thin and dark brown ; epidermis dark 

 brown, closely and finely striate ; umbonial slope very slightly raised, obtusely an- 

 gular ; posterior slope raised into a high carina, very much compressed and covered 

 with loose strife ; cardinal teeth small, striate and double in both valves ; lateral teeth 

 very long, lamellar and straight ; anterior cicatrices distinct, large and well impressed ; 

 posterior cicatrices confluent, large and slightly impressed; dorsal cicatrices in a row 

 across the centre of the cavity of the beaks; cavity of the shell very shallow and Very 

 wide ; cavity of the beaks very shallow and rounded ; nacre purple and very irides- 

 cent. 



Remarks. — A number of fine specimens were given to me by Mr. Wheatley, but 

 none were received in alcohol. This species belongs to the complanatus group, but 

 differs from them all in being more compressed, and in having the whole surface 

 covered with loose strife. These strife are remarkable in this species, the whole 

 surface being usually covered ; and the edges being loose, a variable glossiness is 

 exhibited, except on the posterior slope, which is fuller, and here it is velvety. The 

 strife are usually coarse and rough along the basal and antefior margins. All the 

 numerous specimens I have seen are purple in the nacre, some of them tinged with 

 salmon color. None of the adult specimens were rayed ; some of the young ones are 

 obscurely rayed. 



Uxio micaxs. PL 3, fig. 207. ' 



Testa Iffivi, elliptica, subcomprcssa, valde inrequilaterali, postici: angulata; valvulis subtenuibus, posticG 

 crassioribus ; natibus protuinulis; epiderniide luteo-fusca, valde radiata et valde micante; dentibus 

 cardinalibus parvis, compressis, erectis crenulatisque ; lateralibus longis, lauiellatis rectisque ; uiargariti't 

 vel alba vcl salmonis colore tincta et valde iridescente. 



