I 138 PARREYSI \ 



Parkrysia aurorea (Heude). 



Shell almost evenly elliptical or very slightly rhomboid, solid, 

 scarcely inflated, inequilateral ; beaks only moderately high, 

 small, deeply corrugated, apparently by zigzag ridges ; poste- 

 rior ridge full, narrowly rounded, ending in a blunt point below 

 the median line ; anterior end rounded ; dorsal and basal out- 

 lines almost evenly curved ; dorsal slope obliquely subtruncate ; 

 surface with strong, subradial, tear-like nodules on its earlier 

 growth and, apparently, about three strong, concentric ridges 

 on the later growth ; posterior slope with radial, nodular sculp- 

 ture ; q)idermis fuscous, rayed with green ; pseudocardinals 

 short, much cut up ; muscle scars impressed ; nacre orange. 



Length 34, height 21. diam. 12 mm. 



China. 

 Unio aurorcus Hkude, Conch. Fluv. Nank.. A'lII, 1883, pi. 



Lvii, fig. 106. 

 Pa.rreysia aurorea Simpson, Syn., 1900, p. 849. 



Heude's description is very brief and of little value, and as 

 in several other cases the measurements given are manifestly 

 wrong. This must be an attractive species having an almost 

 evenly elliptical form, decided radial, lachr_vmose sculpture and 

 orange nacre. 



Subgenus Pseudobaphia Simpson, 1900. 



Pseudobaphia Simpson, Syn., 1900, p. 849. 



Shell large, oval, inflated, gaping in front and behind, rather 

 solid, with full beaks, the beak sculpture not seen, posterior 

 part distinctly biangular ; ligament large ; epidermis smooth, 

 brownish, somewhat rayed, right valve with a large, irregu- 

 lar pseudocardinal in front of the beak, with a pit in front of 

 it ; behind it on the hinge are numerous denticles, and at some 

 distance behind two very faint laterals ; left valve with two 

 large pseudocardinals, one behind the other, and two remote, 

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

 dee]) ; posterior scars united, the lower long and oblique ; beak 

 cavities very large, deep ; nacre flesh-colored, scarcely nacreous. 



Animal unknown. 



Type, Unio biesianus Heude. 



