OUADRULA 869 
Margarita (Unio) pumilus Lea, Syn., 1836, p. 20; 1838, p. 17. 
Margaron (Unio) pumilus Lea, Syn., 1852, p. 243; 1870, p. 37. 
Quadrula pumila SIMPSON, Syn., 1GOO, p. 785. 
The type, the only shell I have seen, is a small specimen, so 
badly eroded that nothing whatever of the beak characters can 
be made out. I cannot be sure where it should go, but am in- 
clined to place it in this group. 
QUADRULA BEADLEIANA (Lea). 
Shell subrhomboid or subtriangular, inflated, solid; beaks 
full and high, placed almost centrally ; posterior ridge well de- 
veloped, subangular; anterior end rounded, sometimes slightly 
truncate above; base line well curved; posterior end obliquely 
subtruncated; surface with strong, irregular, concentric 
growth lines; epidermis rich reddish-brown, scarcely shining ; 
pseudocardinals triangular; laterals curved, that of the right 
valve partly double; muscle scars deep; beak cavities not very 
deep ; nacre whitish, purple-tinted or salmon. 
Length 54, height 45, diam. 34 mm. 
Mississippi to eastern Texas. 
Type locality, Pearl River, Jackson, Miss. 
Unio beadleianus Lua, Pr. Ac, N. Sci. Phila., V, 1861, p. 39; 
Jl. Ac. N. Sek Phila., V, 1862, p. 94, pl. xiv, fig. 242; Obs., 
VIII, 1862, pl. 98, pl. xiv, fig. 242. 
Margaron (Unio) beadleianus Lea, Syn., 1870, p. 55. 
Ouadrula beadleiana Simpson, Syn., 1900, p. 786. 
Elliptio beadleianus ORtMANN, Ann. Car. Mus., VIII, 1912, 
p. 268. 
Much more solid and inflated than chickasawhensis and 
rather more truncate behind. 
Ortmann, (1. c.), states that only the outer gills are mar- 
supial. 
QuUADRULA ASKEW! (Marsh). 
Shell somewhat rhomboid, inflated, almost or quite equilat- 
eral, rather solid; beaks full and high; posterior ridge full, 
generally angled above, sometimes biangulate below; anterior 
end rounded, obliquely truncate above; base line generally a 
