﻿I^AMPSILIS 43 



and one thin and truncated one in the right valve; the hinge 

 plate is narrow and rounded in the middle; beak cavities only 

 moderately deep, narrow ; muscle scars rather shallow, smooth ; 

 nacre bluish or purpHsh-white. The female shell has a well- 

 developed marsupial swelling. 



Length 45, height 32, diam. 20 mm. 

 Chattahoochee and Flint Rivers, Georgia. 

 Type locality, Chattahoochee River, Columbus, Ga. 

 Unio lineatus Lea, Pr. Am. Phil. Soc, \, 1840, p. 287 ; Tr. Am. 

 Phil. Soc, Vin, 1842, p. 206, pi. XII, fig. 20; Obs., in, 1842, 

 p. 44, pi. XII, fig. 20.— Chenu, III, Conch., 1858, pi. xxviii, 

 figs. I, I a, lb. — KusTER, Conch. Cab. Unio, 1862, p. 278, pi. 

 xciv, fig. I. — SowERBY, Conch. Icon., XVI, 1868, pi. lxi, 

 fig. 309. 

 Margaron (Unio) lineatus Lea, Syn., 1852, p. 2y\ 1870, p. 41. 

 Lampsilis hinominatus Simpson, Syn., 1900, p. 528. 



This species differs from L. excavata in being smaller and 

 less inflated ; its beaks are not so full and high, the post-ridge 

 is lower and more rounded, and the posterior part of the shell 

 is not much wrinkled. 



Lea's name was preoccupied by Valenciennes (Encyc. Meth., 

 II, 1827, p. 151, pi. ccxLViii, fig. 5) for what is probably U. 

 radiatiis. I changed it to hvnominatus in the Synopsis. 



Lampsilis cariosa (Say). 



Shell slightly obovate, rather thin to subsolid, scarcely in- 

 flated, with a moderately developed, rounded posterior ridge; 

 beaks fairly developed, sculptured with a few coarse, parallel 

 ridges, which are sometimes feebly doubly looped ; surface 

 smooth and shining, straw-color to tawny, sometimes rayed 

 on the posterior slope ; left valve with two compressed pseudo- 

 cardinals, the hinder low and immediately under the beak, and 

 two delicate, remote laterals ; linnge plate rounded in the mid- 

 dle ; right valve with one compressed pseudocardinal and gen- 

 erally a small one above it. and a single lamellar lateral, which 

 is truncated behind. Beak cavities only moderately deep ; an- 

 terior muscle scars shallow, smooth ; posterior scars faint ; na- 



