904 QUADRULA 
hinge plate wide and flat, pseudocardinals ragged; lateral of 
right valve more or less double; beak cavities very deep, com- 
pressed; muscle scars well marked; pallial line remote; nacre 
various shades of purple, thinner behind. 
Length 136, height 104, diam. 50 mm. 
Length 125, height 111, diam. 55 mm. 
Iength go, height 80, diam. 42 mm. 
Mississippi drainage generally; southern Michigan; San 
Saba County, central Texas. — 
Type locality, Ohio River and adjacent streams. 
Obliquaria (Rotundaria) tuberculata RAFINESQUE, Ann. Gen 
Sci. Brux., V, 1820, p. 103. 
Rotundaria tuberculata Acasstz, Arch. fur Naturg., I, 1852, 
p. 48.—OrTMANN, Ann. Car. Mus., VIII, 1912, p. 258, fig. 7. 
Unio tuberculatus Conrap, Monog., V, 1836, p. 43, pl. Xx11.— 
Kuster, Conch. Cab. Unio, 1852, p. 45, pl. 1x, fig. 1—REEVE, 
Conch); Tcon., X Vi) 1864. pl. om tissG, i: 
Quadrula tuberculata SIMPSON, Syn., 1900, p. 795.. 
Unio verrucosus BARNES, Am. J]. Sci., VI, 1823, p. 123, pl. v, 
fig. 6—Hantsy, Biv. Shells, 1843, p. 180, pl. xx1, fig. 24. 
Margarita (Unio) verrucosus Lma, Syn., 1836, p. 16; 1838, 
Del 5: 
Margaron (Unio) verrucosus Lea, Syn., 1852, p. 22; 1870, 
Pp. 34. 
Unio verrucosus purpureus Hirpreru, Am. Jl. Sci., XTV, 1828, 
p. 281. 
Mya verrucosa Eaton, Zool. Text-Book, 1826, p. 216. 
Ouadrula verrucosa BAKER, Mol. Chicago, Pt. 1, 1898, p. 85, 
Pl Orie: 
Unio tuberculosa VALENCIENNES, Rec. Obs. Zool. Anat., IT, 
1O225 232) 
This has usually been placed in the pustulosa group, but the 
character of the beak sculpture, a large number of fine, often 
broken, zigzagged corrugations reaching well out over the 
disk seems to separate it quite distinctly from that assemblage 
and ally it to a number of Mexican and Central American 
