﻿LAMPSILIS 75 



row, rounded hinge plate ; beak cavities not deep ; muscle scars 

 shallow ; nacre bluish, a little thicker in front, generally dark 

 in the cavity of the shell. Male shell bluntly pointed or sub- 

 biangular behind midway up from the base ; female shell con- 

 siderably produced at the post-basal region, subtruncate or 

 rounded behind. 



Length (male) 70, height 40, diam. 25 nun. 



Length (female) 67, height 42, diam. 26 mm. 



Louisiana ; Texas ; Arkansas. 



Type locality, Alexandria, La. 

 Unio reeznanus Lea, Tr. Am. Phil. Soc, X, 1852, p. 272, pi. 



XX, fig. 28 : Obs., V, 1852, p. 28, pi. XX, fig. 28. — Kuster. 



Conch. Cab. Unio., 1861, p. 247, pi. i,xxxi(i, fig. 2. 

 Mariiaron (Unio) reeinaiuis Lka, Syn., 1852, j). 28; 1870, p. 



44- 

 Lampsilis reeiianus Simpson, Syn., 1900, p. 538. 



The relationships of this species are a little doubtful, but the 

 character and texture of the nacre are much like those of /,. 

 radiata. It has characters like some of the species of the lig- 

 amentinn grou]). Its exceedingly small, often feebly developed 

 pseudocardinals and remote laterals and the peculiar color 

 pattern are good characters, as well as the color of its nacre. 



Lampsilis powellii (Lea). 



Shell long, elliptical or long obovate, subsolid to rather thin, 

 subinflated, narrow and rounded in front, with a few irregular 

 growth lines ; beaks only moderately full, their sculpture not 

 observed ; surface tawny, rayless in all the examples seen ; hinge 

 line quite evenly curved ; left valve with two rather small, 

 sharp pseudocardinals and two short, remote laterals ; right 

 valve wdth two pseudocardinals, the upper the smaller, and 

 a single rather long lateral ; beak cavities moderately deep ; 

 anterior muscle scars impressed, posterior scars large, indis- 

 tinct ; nacre dirty whitish, becoming dark and lurid in the cen- 

 ter of the valves, scarcely thickened in front. Male shell feebly 

 biangulate behind midway up from the base ; female shell 

 somewhat produced at the posterior base, wide and rounded 

 behind. 



