752 PLEUROBEMA 
PLwZUROBEMA DOLABELLOIDES (Lea). 
Shell subtriangular, inflated, very solid, with high, full beaks, 
which with the umbonal region curve forward, and are placed 
near the anterior end, inequilateral; anterior end obliquely 
truncate above, rounded into the base below; base curved; 
outline of the dorsal slope strongly curved; posterior ridge 
narrowly rounded, not elevated so much as the radial swell- 
ing in front of it, strongly curved throughout; surface irregu- 
larly concentrically sculptured; epidermis tawny to brownish 
with a few broken rays; pseudocardinals uneven, two in the 
left valve and three in the right; laterals curved, two in the 
left valve and a double one in the right ; beak cavities shallow, 
compressed; muscle scars small, deep; nacre white, straw-color 
or somewhat lurid. 
Length 51, height 55, diam. 36 mm. 
Length 48, height 52, diam. 32 mm. 
Tennessee River drainage. 
Type locality, Holston River, Tenn. 
Unio dolabelloides Lea, Pr. Am. Phil. Soc., I, 1840, p. 288; 
Tr. Am. Phil. Soe. VIEL, 1842, py 215, pix, fie er eS @hse, 
III, 1842, p. 53, pl. xv, fig. 31—CueEnu, Ill. Conch., 1858, 
pl. xxix, figs. 4, 4a, 4b.—Kusrer, Conch. Cab., 1861, p. 214, 
pl. .xxi, fig. 3—Sowesry, Conch. Icon., XVI, 1866, pl. 
XXXVI, fig. 205. 
Margaron (Unio) dolabelloides Lua, Syn., 1852, p. 35; 1870, 
p. 50. 
Pleurobema dolabelloides StMPSON, Syn., 1900, p. 750. 
Unio thornton Lea, Pr. Ac. N. Sei. Phila., I, 1857, p. 83; Jl. 
Ac. N.- Sei: Phila., V1, 1866, pi38; pl. xiv, fies 36.7 Obss OG 
1867, p. 42, pl. xiv, fig. 36. 
Margaron (Unio) thornton Lea, Syn., 1870, p. 56. 
Unio mooresianus Tea, Pr. Ac. N. Sci. Phila., I, 1857, p. 83; 
Jl. Ac. N. Sci. Phila., VI, 1866, p. 39, pl. xiv, fig. 37; Obs., 
Xi2.1867,-p. 42; pl xiv, fetes 
Margaron (Unio) mooresianus LEA, Syn., 1870, p. 39. 
Unio moorenianus Pret, Conch. Sam., IIT, 1890, p. 159. 
