UNIO 679 
Unio extensus Lea, Pr. Ac. N. Sci. Phila., IX, 1857, p. 31; JI. 
me. ON. pet. Phila. DY, 1858, p.\68, pl. xi, fig: 49; Obs., VI, 
1868, p. 67, pl. xu, fig. 40. 
Margaron extensus Lea, Syn., 1870, p. 60. 
Unio subcylindraceus Lea, Pr. Ac. N. Sci. Phila., III, 1873, 
putea eae Ne oe Phila: Vill, 18745"p. 58) plo-xx, fig. 
as Obs: el LS 7A, pr 62) ple xx, figy 57. 
Much elongated, either subrhomboid or almost elliptical, 
with dull dark epidermis and decidedly sulcate sculpture. 
UNIO PERSTRIATUS Lea. 
Shell elongated, subrhomboid, compressed, subsolid, inequi- 
lateral; beaks slightly elevated but not full, their sculpture 
consisting of longitudinal bars; posterior ridge well developed, 
with a tendency to becoming double below, ending behind near 
the base in a rounded point or feeble biangulation; dorsal 
slope obliquely truncated ; base line nearly straight ; dorsal line 
curved a little; surface with fine, concentric sculpture; epi- 
dermis tawny-greenish, or olive, scarcely rayed, covered with 
fine, concentric lamella. very dull; pseudocardinals subcom- 
pressed, rough, single in the right valve and double in the 
left ; laterals straight, delicate; muscle scars large, shallow, the 
posterior ones long elliptical; nacre bluish-white, dull. 
Length 57, height 24, diam. 11 mm. 
Length 72, height 29, diam. 12 mm. 
North and South Carolina. 
Type locality, Abbeville District, S. C. 
Unio perstriatus Lea, Tr. Am. Phil. Soc., X, 1852, p. 255, pl. 
xu, fig. 3; Obs., V, 1852, p. 11, pl. xu, fig. 3—SOwErRBY, 
Conch. Icon., XVI, 1868, pl. xci1, fig. 500.—Srimpson, Syn., 
1900, p. 731. 
Margaron (Unio) perstriatus Lea, Syn., 1852, p. 36; 1870, p. 
57- 
Unio gracilentus Lea, Pr. Ac. N. Sci. Phila., I, 1857, p. 85; 
ji Ac. N«Se: Phila, V, 1862,.p: 58, pl. m1, fig...205 5 Obs., 
V iti, 1862, p: 62, pl. 111, fig- 205: 
Morgaron (Unio) gracilentus Lea, Syn., 1870, p. 60. 
