744 PILEUROBEMA 
base of the shell; surface with irregular growth lines, greenish- 
yellow with two or more broken, narrow or wide rays; pseudo- 
cardinals solid, radial, two in the left valve and three in the 
right; left valve with two laterals, that of the right partly 
double; muscle scars small, impressed; beak cavities shallow ; 
nacre whitish or straw-color, thinner and iridescent behind. 
Length 45, height 36, diam. 20 mm. 
Clinch River, Tennessee. 
Type locality, Clinch, French Broad and Holston Rivers, 
Tenn. 
Umio clinchensis Lea, Pr. Ac. N. Sci. Phila., XI, 1867, p. 81; 
Ji Ac. N.-Sei” Phila.” V1, 1868: 9.2276, pl. xxvii hie a Or 
Obs.; XIT, 1860;-p. 28) pl. xx xvi, fis. OL: 
Margaron (Unio) clinchensis Lea, Syn., 1870, p. 38. 
Pleurobema cuneolus (part), SIMPSON, Syn., 1900, p. 748. 
{n the Synopsis I placed this species in the synonymy of 
Unio cuneolus Lea. lLea’s figured type of the latter is a 
young shell and is more rhomboid and is straighter on the base 
than is the type of his clinchensis. In his collection there is a 
large shell from the Clinch River, which he has labeled Unio 
cuneolus, which approaches his clinchensis so closely that I am 
not sure which species it should be referred to. In general 
cuneolus is a little more rhomboid than clinchensis and has a 
straighter base line, it being sometimes slightly incurved, while 
that of clinchensts is very faintly curved. 
PLEUROBEMA LESLEYI (Lea). 
Shell somewhat drawn out, subtriangular, subrhomboid or 
. nearly evenly ovate, inequilaterai, subsolid to moderately solid, 
subcompressed to scarcely subinflated; anterior end rounded 
or very slightly subtruncate above; base line lightly curved to 
straight: post-dorsal line curved, often elevated nearly to an 
angle in the middle; beaks only moderately high, not very full; 
surface with rather rude growth lines; epidermis dull green- 
ish, tawny or yellowish, with a few broken, green rays, not 
shining ; pseudocardinals two in the left valve and one in the 
right, with occasionally vestigial teeth in the right valve; lat- 
