850 PROCEEDINGS OF TIIK XATIOXAL MUSK I'M. 



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

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

 large, deep; nacre flesh colored, dull.' 

 Animal unknown. 



rPARREYSIA BIESIANA Heude. 



f'nio biesiamts HEUDE, Conch. Finv. Nank.. II, 1877, ]1. xiv, fig. 30. * P.F.TEL, 

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



China. 



Subgenus AOUTICOSTA Simpso i, 1900. 



(Type, Unio chinensis 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 somewhat compressed, vertically ridged, ragged; laterals well 

 developed, strongly obliquely ridged and granular. 



tPARREYSIA CHINENSIS Lea. 



* Unio chinensis LEA, Pr. Ac. Nat. Sci. Phila., XII, 1868, p. 150; * Jl. Ac. Nat. Sci. 



Phila., VI, 1868, p. 325, pi. LIII, fig. 138; *Obs., XII, 1869, p. 85, pi. LIII, fig. 

 138.* P.ETEL, Conch. Sam., Ill, 1890, p. 148. 

 Margaron ( Unio) chinensis LEA, Syn., 1870, p. 30. 



PARREYSIA CHINENSIS var. SQUAMMOSUS Heude. 



* I'nio sinensis var. squammosus HEUDE, Conch. Fluv. Nank., VIII, 1883, pi. 



i.vm, fig. 113. 



PARREYSIA CHINENSIS var. LiEVIS Heude. 



* Unio squammosus var. Itrris HEUDE, Conch. 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.ETEL, Conch. Sam., Ill, 1890, p. 165. 



China. 



Genus PTYCHORHYNCHUS Simpson, 19OO. 

 (Type, Unio pfisleri Heude.) 



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 shiuing; 

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



1 Heude says the beaks are corrugated. 



