30 



DESCRIPTION OF FIFTY-TWO SPECIES OF UNIONID^. 



Hab.—Austm, Texas, Prof. C. G. Forshey, C.E. 



My cabinet, and cabinets of Acad. Nat. Sci. and C. M. Wheatley. 

 j)iam. 1-3, Length 2, Breadth 25 inches. 



Shell plicate, subrotund, very ventricose, very inequilateral, carinate behind and 

 rounded before ; substance of the shell thick, thicker before ; beaks prominent, 

 swollen, recurved and minutely undulate at the tips; ligament long, thick and dark 

 brown; epidermis reddish-brown, without rays, with very distant marks of growth; 

 umbonial slope rounded; posterior slope carinate, with an impressed line in each 

 valve from the beak to the margin ; cardinal teeth thick, raised, sulcate, crenulate 

 and disposed to be treble in the right valve ; lateral teeth long, lamellar, corrugate 

 and slightly curved; anterior cicatrices distinct, rather large, deeply impressed and 

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

 cicatrices placed on the under side of the cardinal teeth ; cavity of the shell deep 

 and rounded ; cavity of the beaks deep and obtusely angular ; nacre silver white 



and very iridescent. 



J2marA-5.— Several specimens of this species were received from Prof, Forshey, 

 with purpuratus Lam., gracilis Bar., Berlandierii (nobis), etc. "When first received, 

 I was disposed to think it to be a marked variety of pUcatus, Lesueur, but it differs 

 from that species in being rotund and in having fewer folds. Li some specimens 

 the folds are so obsolete as scarcely to be observed. The color of the epidermis is 

 also different from plicatus. It has a rufous disposition mingling with a slight 

 greenish tint in the only specimen before me, which is not old. All the specimens 

 were dead shells. The inclination to redness in the epidermis is marked by a line 

 of the hue around the margin of the nacre. The beaks of a single specimen are 

 perfect enough to trace two or three very minute undulations at the tips. In its 

 rotundness and some other characters it is closely allied to Brazosensis (nobis), and 

 when good suites of both shall be obtained it may prove to be only a variety of 

 that species. 



IJnio lenticulaeis. pi. 9, fig. 27. 



Testa Isevi, subrotunda, compressa, lenticulari, suba^quilaterali ; postice obtuse biangulari, antice 

 rotunda; valvulis subtenuibus, antice crassioribus; natibus prominulis; epidermide vel tenebroso- 

 fascavel luteo-fusca, obsolete radiata; dentibus cardinalibus parvis, compressis crenulatisqne ; 

 lateralibus sublongis, lamellatis, corrugatis subcurvatisqne ; margarita albida et iridescente. 



Shell smooth, rounded, compressed, lenticular, nearly equilateral, obtusely bian- 

 gular behind, round before; valves rather thin, thicker before; beaks a little prom- 

 inent; epidermis dark brown or yellowish-brown, obscurely rayed; cardinal teeth 



