UNIO 607 
outline of posterior slope subtruncate, slightly curved; surface 
with rude, irregular growth lines; posterior slope often having 
a few wrinkles; epidermis thick, reddish-brown or chestnut ; 
left valve with two strong, rough pseudocardinals and two 
heavy laterals: right valve with one strong pseudocardinal 
with a small tooth in front of and behind it, with one very 
solid lateral ; beak cavities very shallow with a few small scars ; 
muscle scars small and deep; pallial line impressed, crenate ; 
nacre purplish or salmon. 
Length 120, height 79, diam. 50 mm. 
Length 93, height 6&8, diam. 40 mm. 
Length 128, height 75, diam. 44 mm. 
Mississippi drainage generally; Alabama and Tombigbee 
rivers ; southeast to the Chattahoochee River. 
Type locality, Mississippi and other rivers and lakes. 
Unio crassidens LAMARCK, An. sans Vert., VI, 1819, p. 71.— 
HANLEY, Biv. Shells, 1843, p. 184, pl. xx, fig. 46—CAaLL, Tr. 
Ac. Sci. St. Louis, VII, 1895, p. 12, pl. 11.—Simpson, Syn., 
1900, p. 706.—WaAGNER, Naut., XVIII, 1905, p. 97, pl. vu. 
Margarita (Unio) crassidens Lea, Syn., 1836, p. 19; 1838, p. 
ied 
Margaron (Unio) crassidens Les, Syn., 1852, p. 24; 1870, p. 
37: 
Elliptio crassidens ORTMANN, Ann. Car. Mus., VIII, 1912, p. 
266, figs. 10. Toa. 
?Umo nigra RAFINESQUE, Ann. Gen. Sci. Brux., V, 1820, p. 
Ole Pl L x, Mos, THA: 
Unio niger Say, Am. Conch., VI. 1834.—Conrap, Monog., 
VI. 1836, p. 49, pl. xxv1.—Kuster, Conch. Cab. Unio, 1852, 
p. 25, pl. 1v, fig. 1.—Sowerrsy, Conch. Icon., XVI, 1868, pl. 
LXXvilt, fig. 408. 
?Unio cuneatus BARNES, Am. Jl. Sci., VI, 1823, p. 263.—H11- 
DRETH, Am, Jl. Scie XIV, 1828, p: 279, fig. -3: 
Mya cuneata Faton, Zool. Text Book, 1826, p. 220. 
Unio discus Sowrrey, Conch. Icon., XVI, 1868, pl. Lx, fig. 
310. 
Unio crassus SowERny, Conch. Icon., XVI, 1868, pl. xcv, fig. 
520. 
