gis QUADRULA 
QUADRULA ZONATA (Heude). 
Shell long elliptical, solid, inflated, transversely oblique; 
beaks terminal, full; posterior ridge only moderately devel- 
oped; surface with irregular, concentric ridges and more or 
less nodules on the disk ; posterior slope with a few subradial, 
curved plications, which are more or less subnodulous; epi- 
dermis bright, rich chestnut, sometimes slightly rayed, with 
lighter color; pseudocardinals radial, elongated, radially fold- 
ed or ridged; laterals with vertical striation; beak cavities 
deep, compressed ; nacre white. 
Tength 75, height 55, diam. 40 mm. 
China. | 
Unio sonatus Heung, Conch. Fluv. Nank., VIII, 1883, pl. uxt. 
OQuadrula zonata SiMPSON, Syn., 1900, p. 798. 
Unio tientsinensis Heupr, Conch. Fluv. Nank., VIII, 1883, pl. 
i xige Lis: ‘ 
Very close to tientsinensis, but it has higher, larger, more 
decidedly terminal beaks. the color of the epidermis is differ- 
ent, the concentric ridges are wider and more feeble and the 
pseudocardinals are longer. 
QUADRULA FIBROSA (Heude). 
Shell somewhat elongated, irregularly triangular, solid, in- 
flated, the valves asymmetrical ; beaks full, high, and terminal ; 
anterior end much cut away below the beaks, its outline slight- 
ly curved; base line curved; outline of the dorsal slope a long, 
low curve; posterior ridge only moderately developed, round- 
ed; surface with irregular, concentric, nodulous ridges; epi- 
dermis olive-green or olive-brown; pseudocardinals curved, 
elongated, roughened; laterals curved, strongly vertically stri- 
ate; beak cavities excessively deep, compressed ; anterior scars 
deep, narrow, partly filled with rough nacre; nacre white, the 
posterior calluses strong. 
Length 117, height 63, diam. 50 mm. 
Length 82, height 57, diam. 37 mm. 
China. 
