II50 VTRGUS 



ture ; the curved folds reach the dorsal margin only very near 

 the beaks, but do not near the postero-dorsal angle nor along 

 the posterior slope, but stop 6-12 mm. from it; the post-basal 

 point is also less distinctly angulated.'' 



Ptvchorhynchus murinum (Heude). 



Shell almost evenly oblong elliptical, very slightly rhom- 

 boid, subsolid, inequilateral, beaks low ; posterior ridge widely 

 rounded ; anterior end rounded ; dorsal and basal outlines 

 nearly straight and parallel ; posterior end obliquely subtrun- 

 cate above, rounded below; surface concentrically striate, very 

 feebly plicate on the dorsal sloj^e, blackish-iridescent ; pseudo- 

 cardinals subtriangular, conoid, striate ; laterals remote ; nacre 

 flesh-colored. 



Length 50, height 23, diam. 20 mm. 



Nanking, China. 

 Uiiio comprcssv.s Heudk, Conch. Fluv. Nank., Ill, 1877, pi. 



XXIV, fig. 52. 

 Unio murinns Heude, Conch. Fluv. Nank., VIII, i88j, pi. 



LXii, fig. 121. 

 Unio morinns P.gjTEE, Conch. Sam., Ill, 1890, p. 160. 

 Ptychorhynchns mcertH<s Simpson, Syn., 1900, p. 851. 



In this case again Heude contradicts his measurements. He 

 states that the shell is compressed, and gives the height as 23 

 millimeters and the diameter 20, which would make a much 

 inflated shell. The species is apparently close to schomburg- 

 ianum, but is more elongated in proportion to height, and is 

 not quite so rhomboid. The name comprcssiis given bv Heude 

 to this species was long before preoccupied by Lea in Unio- 

 That the epidermis should be blackish-iridescent ("sub-nigra 

 iridescente") seems peculiar, but that is the statement made in 

 the original description. 



Genus VIRGUS, Simpson, 1900. 



Virgus Simpson, Syn., 1900, p. 851. 



Shell rather solid, elongated, inequilateral, compressed, 

 rounded in front, nearlv straight below, the dorsal line as fa*- 



