PARREVSIA I 139 



Parrb;ysia birsiana (Heude). 



Shell large, rather solid, inflated, subrhomboid, somewhat 

 equilateral ; beaks very full and high, corrugated ; ligament 

 large, brown ; posterior ridge more or less double, ending in a 

 biangulation at and below the median line, the region above it 

 obliquely truncate; epidermis fuscous-olivaceous, slightly ray- 

 ed when young; surface with irregular, concentric sculpture 

 anteriorly and posteriorly nearly smooth and shining medially ; 

 pseudocardinals strong, stumpy, slightly roughened, sho wing- 

 behind them numerous nodules ; laterals feeble, in old shells 

 almost wanting ; anterior scars deep in their hinder portion ; 

 posterior scars large ; beak cavities deep, compressed ; nacre 

 dirty white or flesh-colored. 



Length 106, height 76, diam. 52 mm. 



China. 

 Unio bicsianus IIkude, Conch. Fluv. Nank., 11, 1877, pi. xiv, 



fig. 30. 

 Parreysia hies'w.na vStmpson, vSyn.. 1900, p. 850. 

 Psewdobaphia biesiana Haas. Con. Cab., l^nio. 1910, pi. xr, 



fig. I. 



A large inflated, strong species with a rhomboid form being 

 slig^htly cut away at the lower part of the anterior end. The 

 anterior and posterior ends, gape slightly. The laterals are 

 feeble, but between them and the pseudocardinals there are a 

 number of small tubercles. 



Subgenus Acuticosta Simpson, tqoo. 



Acuticosta Simpson, Syn., 1900, p, 850. 



Shell pointed behind, produced at the center of the base, in-, 

 flated, solid, with a sharp, pinched-up, but vanishing posterior 

 ridge, beaks full, the sculpture strong, zigzag-radial ; epidermis 

 smooth, rayed ; pseudocardinals somewhat compressed, verti- 

 cally ridged, ragged ; laterals well developed, strongly oblique- 

 ly ridged and granular. 



Type, Unio cJiinensis Lea. 



Parreysia chinensis (Lea). 



Shell irregularly elliptical or ovate, somewhat inflated, rather 

 solid, inequilateral ; beaks full and high, sculptured with very 

 strong, often snbnodulous, zigzag sculpture, which extends 



