UNIO 667 
veloped, double, ending behind in a wide biangulation at and 
below the median line; anterior end often cut away, below, 
rounded; basal line straight, rarely a little incurved, some- 
times quite full behind the middle; surface generally rough, 
with uneven growth lines; epidermis dirty tawny or tawny- 
green and faintly rayed in young shells, becoming reddish- 
brown or black in old specimens; pseudocardinals often blur- 
red, low and strongly cross striate; laterals remote, heavy, 
one in the right valve and two in the left; beak cavities shal- 
low ; dorsal scars in a row under the hinge plate; muscle scars 
shallow ; the anterior ones rough; nacre dirty purplish, often 
thicker in front. 
Length 143, height 67, diam. 35 mm. 
Length 140, height 68, diam. 43 mm. 
Length 106, height 55, diam. 25 mm. 
Connecticut River at Northampton, Massachusetts; south 
to the Savannah River, Georgia. 
Type locality, Roanoke River, between Norfolk and ‘Tar- 
boro, N. C.; Altamaha River, Ga. 
Margarita (Unio) roanokensis Les, Syn., 1836, p. 30; 1838, 
pe 20. 
Unio roanokensis LEA, Tr. Am. Phil. Soc., VI, 1838, p. 27, pl. 
vir, fie: 21; Obs., Il, 1838, p: 27, pl. viii, fig. 21—CHENU, 
Ill. Conch., 1858, pl. xx, figs. 6, 6a, 6b—Sowerpy, Conch. 
Icon., XVI, 1868, pl. Lxvi, fig. 341.—SiImMpPSoN, Syn., 1900, 
pe 720. 
Margaron (Unio) roanokensis Lea, Syn., 1852, p. 32; 1870, p 
Cie . 
Unio macer Lea, Pr. Ac. N. Sei. Phila., I, 1857, p. 86; Jl. Ac. 
Niet semua. Vil; 1662, p. 2027p xxix, fig: 271 5 Obs., IX, 
1803; p: 24 spk BRIX, fic. 277- 
Margaron (Unio) macer Lea, Syn., 1870, p. 51. 
Unio -latus gpa Pr Ac, N.ocie Phila:, III; 1859, p.. 171; Jl. 
Ac NaSsc. Pinas IY. 18605 px sa4.<pl. Lit, fig.-159; Obs., 
MILL, 1860;.p.-16, pl. Tins fie E50, 
Margaron (Unio) latus Lea, Syn., 1870, p. 57. 
