PI.EUROBEMA 
“I 
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- 
PLEUROBEMA INTERVENTUM (Lea). 
Shell irregularly oval or elliptical, subinflated, solid, inequi- 
lateral ; beaks full and high; posterior ridge low; dorsal and 
ventral outlines curved; region behind the ligament sometimes 
elevated into a low angle; anterior end rounded or slightly, 
almost squarely truncated; posterior end rounded or feebly 
biangulate; epidermis tawny or tawny-brownish, often with 
dark rest marks, sometimes with a few faint broken rays or 
small dark ‘spots; pseudocardinals small, triangular, two in 
the left valve and one to three in the right ; left valve with two 
laterals ; right valve with a double one; beak cavities shallow ; 
nacre white, iridescent and thinner behind. 
Length 36, height 25, diam. 16 mm. 
{Length 37, height 26, diam. 19 mm. 
Type locality, Cahawba River, Alabama. 
Unio interventus Lea, Pr. Ac. N. Sci. Phila., V, 1861, p. 60; 
Hie AcoN. Sci Phila. V,.1962,p:, o#,, pl. x1, fie. 233% Obs; 
VIET 1S62-peco, pis x1 e233. 
Margaron (Unio) interventus LEA, Syn., 1879, p. 40. 
Pleurobema interventus SIMPSON, Syn., 1900, p. 753. 
Umo pallidofulvus Lea, Pr. Ac. N. Sci. Phila., V, 1861, p. 60; 
ie AceNS set Phila? V5) 1662, p. 83, pl. xt, fig. 222; Obs., 
Vili, 1862; p::S7, pl. x1, fig. 232. 
Margaron (Unio) pallidofulvus Lea, Syn., 1870, p. 40. 
I cannot possibly separate this from the Unio pallidofulvus 
and I do not know why Dr. Lea did so, as both were described 
at the same time. The species is smaller than chattanoogaense, 
it is shorter than that and not quite so inequilateral and it is 
generally lighter colored. 
PLEUROREMA MURRAYENSE (I.ea). 
Shell oval, elliptical or subtriangular, solid, inflated, inequi- 
lateral ; beaks full and high, the greatest diameter of the shel! 
being just below them; posterior ridge low, narrowly rounded : 
anterior end nearly squarely subtruncated or rounded; dorsal 
and basal outlines curved, the latter usually more strongly so; 
posterior end narrowly rounded ; epidermis dull, ashy or green- 
ish-brown, with strong, sometimes greenish, rest marks; 
