754 PLEUROBEMA 
Something like P. appressum, but not so compressed on the 
disk. It seems close to dolabelloides, but the beaks are hardly 
so high and the color and texture of the epidermis differs a 
little from that of either of them. I have only seen one shell 
that I am sure is valid, the type. Another that Dr. Lea has 
placed with that 1s his Unio pudicus, I think. 
PLEUROBEMA BARNESIANUM (Lea). 
Shell nearly elliptical, rather solid, convex or subinflated, 
inequilateral; beaks rather high and full; posterior ridge 
strong, subangular or narrowly rounded, ending below the 
median line in a point; anterior end nearly evenly rounded; 
base line curved; dorsal line lightly curved, meeting the outline 
of the subtruncated dorsal slope at an angle; surface with 
fine, uneven growth lines; epidermis tawny to dirty greenish- 
brown, faintly rayed, subshining ; pseudocardinals small, radial, 
two in the left valve and three in the right; laterals two in the 
left valve and a somewhat double one in the right; beak cavi- 
ties shallow ; muscle scars smail, impressed ; nacre white, tinted 
purple. 
Length 44, height 34, diam. 20 mm. 
Length 37, height 27, diam. 15 mm. 
Cumberland and Tennessee River systems. 
Type locality, Cumberland River, Tenn. 
Unio barnesianus Lea, Tr. Am. Phil. Soc., V1,.1838, p. 31, pl. 
x, fig. 26; Obs., II, 1838, p. 31, pl. x, fig. 26—HANLEy, Biv. 
Shells, 1843, p. 185, pl. xxtu, fig. 14.—Cuenu, Ill. Conch., 
1858, pl. xrx, figs. 2, 2a, 2b>—Sowersy, Conch. Icon., XVI, 
1866, pl. XxxIV, fig. 180. 
Vargarita (Unio) barnesianus LEA, Syn., 1836, p. 20; 1838, p. 
Ge 
Margaren (Unio) barnesianus LEA, Syn., 1852, p. 24; 1870, p. 
38. 
Pleurobema barnesiana SIMPSON, Syn., 1900, p. 751. 
Unio ravenelianus Rerve, Conch. Icon., XVI, 1864, pl. xvt, 
fig. 70. 
Unio tellicoensis Lua, Pr. Ac. N. Sci. Phila., II, 1872, p. 155; 
Jl. Ac. N.. Scis Phila, VINE 1874; (p: 31) ph xyes 26-7Obs. 
XL, 1874, peesepl- x, exec: 
