PILEUROBEMA 781 
in the right; beak cavities shallow; muscle scars small; nacre 
white or bluish, thin and iridescent behind. 
Length 37, height 24, diam. 20 mm. 
Length 38, height 22, diam. 17 mm. 
Coosa River drainage, Georgia and Alabama. 
Type locality, Coosawattee River, Murray Co., Ga. 
Unio hanleyanus Lea, Tr. Am. Phil. Soc., X, 1852, p. 279, pl. 
XXIII, fig. 37; Obs., V, 1852, p. 35, pl. xxi, fig. 37.REEvE, 
Conch. Icon., XVI, 1864, pl. xvut, fig. 76—Sowerey, Conch. 
feony OVE, - 1866. pl. svi, fig. 240. 
Margaron (Unio) hanleyanus Lea, Syn., 1852, p. 26; 1870, 
p. 40. 
Pleurobema hanleyana SiMPSON, Syn., 1900, p. 759. 
This species is close to ?. johannis but the latter seems to 
constantly differ in the texture and color of the epidermis. 
P. hanleyanum is never clouded nor marked with green, it is 
more cloth-like and has the dark rest marks in all cases. It is 
a solider, darker colored species than flazidulum. 
PLEUROLEMA FLAVIDULUM (Lea). 
_ Shell subelliptical, convex or subinflated, inequilateral, rath- 
er thin to subsolid; beaks moderately full and elevated; pos- 
terior ridge well developed, narrowly rounded, ending in a 
point at the median line; epidermis dirty yellow, tawny or 
dirty greenish, sometimes with one or two rays on the poste- 
rior slope; pseudocardinals subcompressed, two in the left 
valve, and one to three in the right ; two delicate laterals in the 
left valve and one in the right; beak cavities shallow ; muscle 
scars scarcely impressed; nacre whitish or purplish, a little 
thinner and iridescent behind. 
Length 37, height 21, diam. 15 mm. 
Type locality, Columbus, Mississippi. 
Unio: fazvidulus Warns, Pr: Ac’ N. Sei. Phila. V, 1861, p. 39; 
{iA N. Set.Phila., V, 1862; p.o77: pl. xv; fig. 245 ; Obsi, 
VIII, 1862, p. tor, pl. xv, fig. 245. 
Margaron (Unio) flavidulus Lua, Syn., 1870, p. 40. 
Pleurobema flavidulus Simpson, Syn., 1900, p. 759. 
More delicate, thinner and less compressed than either jolan- 
nis or hanleyanum. It is sometimes flushed a little with green. 
