926 QUADRULA 
Group of Quadrula rochechouarti. 
Shell rhomboid, with a strong posterior ridge, rounded be- 
fore, incurved below, and somewhat biangulate on the posterior 
base, with very strong folds on posterior slope, which begin 
on the posterior ridge as knobs; surface strongly pustulous; 
beaks rather well forward, sculpture not seen; epidermis con- 
centrically wrinkled, black and rough; pseudocardinals strong, 
somewhat radial, rough, striate ; laterals more or less vertically 
striate, secondary lateral in right valve well developed; beak 
cavities very deep, compressed ; posterior calluses faint. 
Animal unknown, 
QUADRULA ROCHECHOUARTI (Heude). 
Shell subtriangular, solid, scarcely inflated, inequilateral ; 
valves scarcely, if at all, twisted ; beaks high and full; posterior 
ridge very strong, curved, subangular, ending at the base of 
the shell; anterior end evenly rounded; base line decidedly 
sinused in front of the posterior ridge; outline of dorsal slope 
lightly curved; post-basal part somewhat obliquely truncated ; 
surface, except the extreme anterior end, covered with very 
strong, often lachrymose or double, tubercles; dorsal slope 
sculptured with very strong, curved ridges; epidermis black- 
ish, thick, often cracking off; pseudocardinals strong, radial, 
radially striate; laterals vertically striate, that of the right 
valve partly double; anterior muscle scars partly filled with 
roughened nacre; beak cavities enormously deep, compressed ; 
nacre dull purplish. 
Length 130, height 92, diam. 48 mm. 
Province of Kiang-su, China. 
Unio rochechouarti Hrupr, Conch. Fluv. Nank., I, 1875, pl. v- 
fig. 13. 
Quadrula rochechouarti SIMPSON, Syn., 1900, p. 800. 
A remarkably strong, rude species, which recalls certain 
specimens of our Tritogonia tuberculata. ‘The two specimens 
in the National Museum collection are from Heude, and are 
more elongated than the figure given by him. 
