788 PLEUROBEMA 
muscle scars small, shallow; nacre bluish-white, thinner and 
iridescent behind. 
Length 37, height 28, diam. 16 mm. 
Type locality, Escambia River, Florida. Also, Flint River. 
Rhoadsville, Georgia. 
Umo strodeanus B. H. Wricut, Naut., XII, 1808, p. 5. 
Pleurobema strodeana Stmpson, Pr. Ac. N. Sci. Phila., 1900, 
p: 81, plot, hig. 35 Syn, 1900, pp. 7ole 
The type, whose dimensions are given above, may be a young 
shell. Its short, nearly elliptical form and black epidermis 
together with the almost blue nacre distinguish it from allied 
species. 
PLEUROBEMA PATSALIGENSE Simpson. 
Shell nearly elliptical or subrhomboid, convex or subinflated, 
scarcely subsolid, inequilateral; beaks moderately full and 
high ; posterior ridge subangular or narrowly rounded, ending 
in a point or slight biangulation below the median line; sur- 
face finely and unevenly concentrically sculptured; epidermis 
tawny-green flushed with brown at the umbonal region and 
generally faintly rayed, rather dull and cloth-like, sometimes 
slightly blistered; pseudocardinals two in the left valve and 
one to three in the right; left valve with two laterals; right 
valve with one; beak cavities not deep; muscle scars small; 
nacre dirty whitish, sometimes tinted purple and blotched. 
Length 45, height 33, diam. 18 mm. 
Length 43, height 25, diam. 17 mm. 
Type locality, Little Patsaliga Creek, Crenshaw Co., Ala- 
bama. 
Pleurobema patsaligensis Stimpson, Pr. Ac. N. Sci. Phila., 
1900; p. 82, pl. 11, fig: 1; Syn. 1960; Pp. 70m: 
Thinner and generally shorter than P. simulans, usually 
lighter colored and having duller nacre. 
PLEUROBEMA STRIATULUM (Lea). 
Shell short, subrhomboid, subsolid or solid, convex or sub- 
inflated, slightly inequilateral ; base somewhat rounded; beaks 
full and high, their sculpture consisting of ridges which are 
