﻿LAMPSIUS 141 



brig^htly rayed and polished. It seems to so completely blend 

 with amygdahim that I cannot make any satisfactory separa- 

 tion. It might however bear Gould's name varietally. 



Lampsilis suda (Lea). 



Shell elliptical or slightly obovate, subinflated, scarcely sub- 

 solid, beaks nearly central, rather full but not high, their sculp- 

 ture consisting of a few doubly-looped ridges, the hinder loops 

 somewhat angular below ; posterior ridge rather well developed, 

 rounded ; surface with irregular, concentric growth lines, shin- 

 ing, tawny or pale brownish with regular, somewhat broken 

 rays ; left valve with two compressed peudocardinals, the an- 

 terior much higher and triangular, and two delicate, nearly 

 straight laterals ; there are two pseudocardinals in the right 

 valve, the lower the larger, and one lateral ; beak cavities shal- 

 low ; nacre bluish-white, rather dull ; muscle scars shallow. 

 Male shell elliptical or very feebly subrbomboid, the posterior 

 point midway up from the base or a little less ; base much 

 rounded. Female shell wider behind than in front, with a 

 blunt, rounded posterior point two-thirds of the way up from 

 the base, and a small, rounded marsupial swelling situated near 

 the posterior end. 



Length 42, height 2y, diam. 16 mm. 



Type locality, Macon and Dry Creek, near Columbus, Geor- 

 gia. Also, Abbeville, South Carolina. 

 Unio concaz'iis Lea, Tr. Am. Phil. Soc, X, 1852, p. 260, pi. 



XV, fig. II ; Obs., V, 1852, p. 16, pi. XV, fig. IT. — SOWBRBY, 



Conch. Icon., XVI, 1868, pi. xcii, fig. 504. 

 Margaron (Unio) concaviis Lea, Syn., 1852, p. 29 ; 1870, p. 46. 

 Unio sudus Lea, Pr. Ac. N. Sci. Phila., IX, 1857, p. 170; Jl- 



Ac. N. Sci. Phila., IV, 1859, p. 194, pi. xxi, fig. 77 ; Obs.. 



VII, 1859, P- 12, pi. XXI, fig. 77. 

 Margaron (Unio) siLdus Lea, Syn., 1870, p. 46. 

 Lampsilis sudus Simpson. Syn.. 1900, p. 561. 



This seems to be a rare shell, and I have never seen more 

 than half a dozen specimens of it. Of these a single young 

 one is a female and I cannot be certain whether the species 



