108 NEW UNIONID.'E OF THE UNITED STATES. 



Remarks. — This small species is remarkably tumid and heavy. In or.tline it is 

 between castaneus and deciszis. It is more oblique than the former, and less so than 

 the latter. It cannot be confounded with either of them. The lines of growth are 

 somewhat distant, well marked by light brown bands, the upper ones being bordered 

 with darker bands. The upper portion is disposed to be smooth and greenish, while 

 the lower is brown and striate. The beaks are very nearly terminal, and the anterior 

 slope is broad and flat, while the posterior one is very narrow. The color of the 

 epidermis seems to be very variable, though the greenish brown predominates. 



Maegaritana Alabamensis. pi. 16, fig. 249. 



Testa, laevi, oblonga, inflatii, ad latere paulisper planulata, injequilaterali, postice obtus6 biangulata, antic6 

 oblique rotundafa; valvulis subcrassis, antlce paulisper crassioribus ; natibus prominulis, ad apices 

 rugosc-undalatis; epidermide luteo-olivii polita, eradiata; dentibus cardinalibus parvis, suberectis ; 

 margarita alba et saltuonea et iridescente. 



Shell smooth, oblong, inflated, slightly flattened at the sides, inequilateral, obtusely 

 biangular behind, obliquely rounded before ; valves somewhat thick, slightly thicker 

 before; beaks a little prominent, rugosely undulate at the tips; epidermis yellowish 

 olive, polished, without rays; cardinal teeth small, somewhat erect; naci'e white and 

 salmon, very iridescent. 



Proc. Acad. Nat. Sci. 1861, p. 41. 



Eab. — Talladega Creek, Alabama. Wm Spillman, M. D. 



My cabinet and cabinet of Dr. Spillman. 

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



Shell smooth, oblong, inflated, somewhat flattened at the sides, inequilateral, ob- 

 tusely biangular behind and obliquely rounded before ; substance of the shell some- 

 what thick, slightly thicker before ; beaks a little prominent, with a few coarse 

 undulations at the tips ; ligament rather long, very thick and dark brown ; epidermis 

 yellowish olive, polished, without rays, with somewhat distant marks of growth ; 

 umbonial slope inflated and rounded ; posterior slope narrow-elliptical, slightly cari- 

 nate, with two impressed lines on each valve; cardmal teeth small, somewhat erect, 

 compressed, and direct in the right valve and tuberculate in the left; anterior cica- 

 trices confluent, very large and well impressed ; posterior cicatrices confluent, very 

 large and slightly impressed; dorsal cicatrices in the right valve placed on the under- 

 side of the plate posterior to the cardinal tooth, in the left valve on the base of the 

 cardinal tooth; cavity of the shell deep and wide ; cavity of the beaks rather shallow, 

 and subangular ; nacre white, tinted with salmon color in the cavity of the beaks, 

 and iridescent. 



Eemarks. — It is to be regretted that a single specimen only should be described 

 from, and this without the soft parts. This is a very distinct species, and is perhaps 



