QUADRULA 883 
QUADRULA COCCINEA (Conrad). 
Shell subtriangular, convex to moderately inflated, inequi- 
lateral, solid; beaks high, moderately full, turned forward over 
a lunule, their sculpture a few corrugations which curve up 
behind; anterior end generally obliquely truncated above, 
rounded below ; base line straight or curved; outline of dorsal 
slope curved, usually subangulate behind the ligament; pos- 
terior ridge narrowly rounded above, widely rounded below, 
ending near the base in a blunt point or faint biangulation ; 
the shell has its greatest diameter in front of the middle but 
there is no radial depression behind it; surface with irregular 
growth lines ; epidermis brownish or reddish-brown, somewhat 
cloth-like when not rubbed; tawny or yellowish-green and 
raved when young; pseudocardinals triangular ; lateral of left 
valve more or less double; beak cavities moderately deep, com- 
pressed; muscle scars impressed; nacre rich pink, salmon- 
tinted, flesh-colored or white, thinner and iridescent behind. 
Length roo, height 76, diam. 43 mm. 
Length 90, height 74, diam. 41 mm. 
Entire Upper Mississippi drainage; St. Lawrence basin in 
various localities. | 
Type locality, Mahoning River, near Pittsburgh. 
Unio coccinetis CONRAD, Monog., III, 1836, p. 29, pl. x11, fig. 
fee br. im hike sec. Villn83s,-p: 12, pl..v, fis.12; 
Obs., II, 1838. p. 12, pl. v, fig. 12—HANLEy, Biv. Shells, 
1843, p. 203, pl. xx, fig. 54——Kustrer, Conch. Cab., 1852, 
p. 49, pl. x, fig. 2.—CuHeENv, II]. Conch., 1858, pl. xxv, figs. 
4, ta, 4b.—Sowerry, Conch. Icon., XVI, 1868, pl. xcrv, fig. 
Hie. 
Margarita (Unio) coccineus LEA, Syn., 1836, p. 34; 1838, p. 23. 
Margaron (Unio) coccineus Lea, Syn., 1852, p. 35; 1870, p. 56. 
Ouadrula coccinea BAKER, Moll. Chicago, Pt. 1, 1898, p. 79, pl. 
XIV, fig. 1; pl. xrx, fig. 3—S1mpson, Syn., 1900, p. 788. 
Pleurobema coccineum OrRtMANN, Ann. Car. Mus., VIII, 
Ione p. 263: 
Unio rubens Menke, Syn., Meth. Moll., 1828, p. go. 
