P.VRRFCYSIA I 123 



anterior end narrowed, rounded ; dorsal outline arched ; dorsal 

 slope obliquely rounded ; base line straight, sometimes very 

 slightly incurved medially ; surface olivaceous-fuscous, shining ; 

 pseudocardinals conical, simple ; laterals short, obsolete. 



Length 60, height 30, diam. 25 mm. 



Province of Ngan-Hoei, China. 

 Unio modestns Heude. Conch. Fluv. Nank., II, 1877. pi. xiv, 



fig. 29. 

 Unio simpularis Heude, Jl. de Conch., XXXII, 1884, p. 20. 

 Parreysia simpularis Simpson, Syn., 1900. p. 845. 



T can only guess at the relationship of this form, of which 

 Heude gives only an outline figure and a very meagre Latin 

 description. He states that the shell is compressed but his 

 dimensions (given above) show it to be much inflated. He 

 also states that the beaks are corrugated. It may possibly be 

 a Pseudodon, though the general form would indicate that it 

 was related to P. c orb is. 



The name modestns having been used previously for a Bra- 

 zilian Unio, Heude afterwards changed his name to simpular- 

 is. But I can not find that this Brazilian, form, which is gen- 

 erally credited to Ferussac, was ever described, hence Heude's 

 first name must stand. It is quite probable that this should 

 form a separate group. 



Parreysia trisui.cata (Heude). 



Shell small, subtriangular, solid, subinflated, inequilateral ; 

 beaks and umbonal region full, having three strong, low, sub- 

 concentric sulcations ; posterior ridge full, feebly double or 

 rounded ; terminating in a faint biangulation ; dorsal outline 

 •strongly arcuate ; base line much more nearly straight, so that 

 the shell is somewhat triangular : epidermis yello-wish-fuscous, 

 transversely, minutely striate ; pseudocardinals conical, obtuse ; 

 laterals short, obsolete ; nacre flesh-colored. 



Length 30, height 17, diam. 11 mm. 



China. 

 Unio trisiilcatiis Heude, Conch. Fluv. X^ank., VIII. 1883, pi. 



Evn, fig. 108. 

 Parreysia trisulcata Simpson. Syn., 1900, p. 845. 



