928 QQUADRULA 
and tubercles, which show a tendency to an arrangement in 
curved lines; epidermis chestnut to blackish; hinge strong; 
pseudocardinals radial, radiately striate; laterals granular, 
showing traces of vertical striation; beak cavities very deep. 
compressed ; nacre silvery. 
Animal unknown. 
QUADRULA BAZINI (Heude). 
Shell long ovate, solid, very inequilateral, scarcely inflated ; 
beaks only moderately full, or elevated; anterior end rounded; 
base and dorsal outlines lightly curved to a point some distance 
above the base; posterior ridge elevated; surface more or less 
covered with knobs or tubercles that have a tendency to be 
arranged in curved, subvertical rows; epidermis light and 
dark brown, clouded, shining; pseudocardinals radial, radially 
striate; laterals with slight vertical striation, that of the right 
valve partly double; beak cavities deep, compressed; pallial 
line not very remote; nacre white. 
Length 105, height 57, diam. 33 mm. 
China. 
Unio bazini Heupr, Conch. Fluv. Nank., II, 1877, pl. rx, fig. 
20. 
Quadrula bazini Simpson, Syn., 1900, p. 800. 
Heude’s figure differs considerably from the specimen from 
him in the National Museum collection, being much less strong- 
ly tuberculate and having the later growth of the shell smooth, 
while that in the Museum is noduled throughout. The shell is 
more ovate than triclavws and lacks the ponderous knobs on 
the posterior ridge. 
Group of Quadrula leat. 
Shell obovate, obtusely pointed behind; posterior ridge low ; 
whole surface generally tuberculate or knobbed, with strong, 
radial, curved ridges on the posterior slope; beaks rather low, 
the sculpture coarse, irregular, broken bars somewhat doubly 
looped and swollen on the posterior ridge, with strong, radiat- 
ing ridges behind them; pseudocardinals solid, often com- 
