850 PROCEEBIXGS OF THE NATIONAL MUSEUM. vouxxii 



blurred laterals; two upper anterior muscle scars uuited, very deep; 

 posterior scars united, the lower long and oblique; beak cavities very 

 large, deep; nacre flesh colored, dull.' 

 Animal unknown. 



tPARREYSIA BIESIANA Heude. 



* f7«?o ?)deswm»s Heude, Conch. Fluv. Naiik., II, 1877, pi. xiv, fig. 30. — *P/ETEL, 



Conch. Sam., Ill, 1890, p. 146. 



China. 



Subgenus ACUTICOSTA Simpson, 1900. 



(Type, Unio chhiensis Lea.) 



Shell pointed behind, produced at the center of the base, inflated, 

 solid, with a sharp, pinched-up, but vanishing posterior ridge, beaks full, 

 the sculpture strong, zigzag radial; epidermis smooth, rayed; pseudo- 

 cardinals someM^hat compressed, vertically ridged, ragged; laterals well 

 developed, strongly obliquely ridged aud granular. 



t PARREYSIA CHINENSIS Lea. 



* Unio cMnensis Lea, Pr. Ac. Nat. Sci. Phila., XII, 1868, p. 150; * Jl. Ac. Nat. Sci. 



PhUa., VI, 1868, p. 325, pi. liii, fig. 138; *Obs., XII, 1869, p. 8.5, pi. liii, fig. 

 138.—" P^ETEL, Conch. Sam., Ill, 1890, p. 148. 



* Margaron ( Unio) cMnensis Lea, Syn., 1870, p. 30. 



PARREYSIA CHINENSIS var. SQUAMMOSUS Heude. 



* Unio sinensis var. squammosus Heude, Conch. Fluv. Nank., VlII, 1883, pi. 



LVIII, fig. 113. 



PARREYSIA CHINENSIS var. LiEVIS Heude. 



* Unio squammosus var. Iwris Heude, Couch. Fluv. Nank., VIII, 1883, pi. lix, 



fig. 116. 



China. 



PARREYSIA RETIARIA Heude. 



" Unio retiarius Heude, Conch. Fluv. Nank., VIII, 1883, pi. lvii, fig. 107. — 

 ■*P^TEL, Couch. Sam., Ill, 1890, p. 165. 



China. 



Genus PTYCHORH YNCHUS Simpson, 1900. 

 (Type, Unio pfisteri 'Re.wAe.) 



Shell elongate, elliptical, round in front, pointed behind, the point 

 being midway of the height of the shell, solid, slightly inflated, with 

 a faint posterior ridge; beaks rather low, sculpture not seen; the pos- 

 terior slope sculptured with strong, upcurved ridges, which sometimes 

 extend slightly on to the disk, which is otherwise smooth and shining; 

 left valve with two rather stumpy, roughened pseudocardinals and 1 or 2 



' Heude says the beaks are corrugated. 



