PLEUROBEMA 74 
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PLEUROBEMA CUNEOLUS (Lea). 
Shell subtriangular or subrhomboid, convex to subinflated, 
inequilateral, solid; beaks high, moderately full; anterior end 
usually obliquely truncated above, rounded below, sometimes 
rounded throughout; basal line nearly straight; post-dorsal 
line curved, rising in the middle almost or quite to an angle; 
posterior ridge subangular, ending below in a point at the base, 
not so high as the radial swelling in front of it; epidermis 
greenish-yellow or yellow-green, with wide or narrow, broken 
rays, rather dull; pseudocardinals rough and uneven, double 
in each valve, laterals curved, that of the right valve partly 
double; muscle scars small, impressed; nacre white. 
Length 50, height 38, diam. 23 nim. 
Length 45, height 36, diam. 19 mm. 
Tennessee River system. 
Type locality, Holston River, Tenn. 
Unio cumeolis Vex, Pr Am. Phil.-Soc., 1, 1840, p. 286% Tr. 
Aime Eiko soc, Vill. 1842p) 163) pl. vil, fig. 3: Obs:, 1, 
$842, p. 31, pl. vi, fig. 3—Cuenu, Ill. Conch., 1858, pl. xxx, 
figs. 2, 2a, 2b.—Kuster, Conch. Cab. Unio, 1861, p. 182, pl. 
LXvu, fig. 4—Rreve, Conch. Icon., XVI, 1865, pl. xxir, 
fee TO? 
Margaron (Unio) cuneolus Lea, Syn., 1852, p. 24; 1870, p. 38. 
Pleurobema cuneolus SIMPSON, Syn., 1900, p. 748. 
\ rather compressed species when compared with those that 
precede it. The post-dorsal line is quite high behind the liga- 
ment, so that the shell becomes in some cases subrhomboid. 
The beak cavities are not so deep as those of edgarianum, the 
muscle scars are comparatively shallow. I cannot separate 
Jjea’s Unio cuneolus and clinchensis by any characters of 
value. 
PI,EUROBEMA CLINCHENSE (Lea). 
Shell subtriangular, inequilateral, scarcely inflated, solid; 
beaks high but not very full; anterior end rounded; base near- 
ly straight: post-dorsal line curved, elevated into a low angle 
medially ; posterior ridge rounded, ending near the posterior 
