QUADRUTA 817 
QUADRULA PERPLICATA (Conrad). 
Shell subrhomboid, inflated, solid, inequilateral; beaks full 
and high, turned forward over a well-marked lunule, their 
sculpture a few strong, irregular bars; anterior end rounded, 
a little narrower than the posterior end, often cut away a little 
below ; base line: curved; post-dorsal slope usually developed 
into a slight wing, the hinder part obliquely truncate; surtace 
with light, irregular, concentric ridges, and with very strong, 
oblique ridges on the hinder half of the disk that run well 
on to or cross the posterior ridge; epidermis dark brown or 
nearly black, often subshining; pseudocardinals strong, radial, 
much split, two in the left valve and three in the right; two 
laterals in the left valve and one in the right; muscle scars 
shallow, the anterior ones rough; beak cavities deep, com- 
pressed; nacre white. generally purple-tinted and iridescent 
behind. 
Iength 145, height 110, diam. 60 mm. 
Length 87, height 67, diam. 55 mm. 
Alahama River drainage and streams flowing into the Gulf 
of Mexico west to central Texas, north to southern Kansas. 
Type locality, Jackson, La. 
Umo perplicatus Conrap, Pr. Ac. N. Sci. Phila., I, 1841, p. 
fOr ae, Ne ocls nila. 1850, -p. 276, pl. xxxvin, fig. 
—Rerve, Conch. Icon., XVI, 1864, pl. 1x, fig. 35. 
Margaren (Unio) perphicatus Lea, Syn., 1852, p. 20; 1870, p. 
20. . 
Plectomerus perplicatus Conrap, Pr. Ac. N. Sci. Phila., VI, 
£953, p: 201. 
Ouadrula perplicata Stmeson, Syn., 1900, p. 767. 
Crenodonta perplicata ORTMANN, Ann. Car. Mus., VIII, ro12, 
Pp. 247. 
Unio atrocostatus Lea, Tr. Am. Phil. Soc., X, 1848, p. 70, pl. 
im ne.-5 Obs. 1V, 1848. p. 44) pl. 1, fig. 5. 
Margaron (Unio) atrocostatus Lea, Syn., 1852, p. 20; 1870, 
p. 20. 
Unio pearlensis Conrad, Tr. Am. Phil. Soc., VII, 1855, p. 256. 
—Reeve, Conch. Icon., XVI, 1864, pl. xt, fig. 42. 
Unio perlensis Pater, Conch. Sam., IIT. 1890, p. 163. 
bo 
