QUADRULA 885 
Some of the specimens are distorted and have the upper part 
of the anterior end decidedly angled. But all are of light, deli- 
cate structure. The name paupercula having already been 
used by Lea for a species of Quadrula, | am obliged to change 
the name of this form. 
QUADRULA SOLIDA (Lea). 
Shell having almost the form of a right-angled triangle, gen- 
erally inflated, solid, inequilateral ; beaks high and full, turned 
forward over a wide lunule, their sculpture a few strong, irreg- 
ular ridges that curve up behind; anterior end squarely or 
somewhat obliquely truncated above, rounded below ; base line 
nearly or quite straight ; outline of dorsal slope lightly curved ; 
posterior ridge not greatly elevated, rounded, ending in a 
rounded point at the base of the shell; there is a wide inflation 
running from the beaks down to a little in front of the middle 
base; between this and the posterior ridge there is scarcely 
any depression ; surface with irregular growth lines ; epidermis 
greenish-brown to reddish-brown, somewhat silky when fresh, 
slightly rayed in young shells ; pseudocardinals strong, ragged ; 
lateral of the right valve usually somewhat double; muscle 
scars deep ; beak cavities moderately deep; nacre white, yellow- 
ish, salmon-tinted or pink. 
Length 115, height 75, diam. 43 mm. 
Length 110, height 67, diam. 44 mm. 
Length 70, height 68, diam. 41 mm. 
Length 72, height 65, diam. 42 mm. 
Ohio, Cumberland, and Tennessee River systems; south to 
Louisiana; west to Arkansas and Kansas; north to Minnesota ; 
east, through Wisconsin, Illinois, and Indiana, to Ohio. 
Type locality, Ohio River, Cincinnati; Mahoning River, 
Ohio. 
Unio solidus Lea, Tr. Am. Phil. Soc., VI, 1838, p. 13, pl. v, fig. 
13; Obs., II, 1838, p. 13, pl. v, fig. 13—HANLEy, Biv. Shells, 
1843, p. 186, pl. xxi, fig. 15 —CHENU, Ill. Conch., 1858, pl. 
XXV, figs. 2, 2a, 2b.—-Kuster, Conch. Cab., 1861, p. 258, pl. 
LXXXvil, fig. 4.—RreEve, Conch. Icon., XVI, 1865, pl. xxvIt, 
fig..1 33. 
