674 UNIO 
sharp, ragged; laterals delicate, curved; muscle scars large, 
shallow ; beak cavities shallow ; nacre bluish or milky-white. 
Length go, height 52, diam. 28 mm. 
Georgia. 
Type locality, Flint River, Macon, Ga. 
Unio subniger Lea, Pr: Ac. Ne sei. Philas 1 X= 1857; pa a72e 
Jl Ac. NoSei.:Phila., TV 1859, 1p: 160,.pl: xx ties yon Ons 
VII, 1850, p. 14, pl. xxu, fig. 79—SiIMpson, Syn., 1900, p. 
730. 
Margaron (Umo) subniger LEA, Syn., 1870, p. 52. 
This shell is shaped much like forms of U. complanatus, 
but the posterior ridge curves up in the middle and it is covered 
with decided concentric sculpture. 
UNIO BURKENSIS Lea. 
Shell oblong, subelliptical or subrhomboid, thin, subcom- 
pressed, inequilateral ; beaks neither full nor high, their sculp- 
ture not seen; posterior ridge moderately full, double, ending 
behind in a biangulation at and below the median line; base 
line nearly straight, anterior end subtruncate above; surface 
slightly marked with incremental and faint radiating sculpture ; 
epidermis dull dirty green, showing vestiges of rays, subshin- 
ing ; pseudocardinals small, sharp, nearly smooth, compressed, 
one in the left valve and two in the right; laterals delicate, 
straight ; muscle scars shallow ; nacre lurid purplish, iridescent 
behind. 
Length 70, height 34, diam. 17 mm. 
North Carolina; south to Georgia. 
Type locality, Buckhead Creek, Burke Co., Ga. 
Unio burkensis Lea, Pr. Ac. N. Sci. Phila., TI, 1859, p. 112; 
JL Ac. Ny, Seis Phila. IV; 1850, p. 205, pL sexviag ees, 
Obs., VII, 1850, p. 33, pl. xxv, fig. 95.—Srmpson, Syn., 
1900, p. 730. 
Margaron (Unio} burkensis Lea, Syn., 1870, p. 60. 
Unio dissimilis Lea, Pr. Ac. N. Sci. Phila., II, 1872, p. 161; 
Ii., Ac. Ne Sei Phila., VILL a8745p. 53, pl. ora ee 
Obs., XITI, 1874, p. 57, pls xvmu, fig. 52. 
