p\rre:ysia 1 1 09 



scars shallow; beak cavities deep; nacre whitish, flesh-colored 

 or salmon-tinted, thickened in front, iridescent behind. 



Length 62. height 7,S, diam. 25 mm. 



Length 61, height 40, diam. 22 mm. 



Wynegunga River, Bengal. 

 Unio zipyncgnngccnsis Lka, Pr. Ac. N. Sci. Phila.. IIL 1859, p. 



331 ; Jl. Ac. N. Sci. Phila., IV, i860, p. 271, pi. xi.v, fig. 151 ; 



Obs., VIL i860, p. 89, pi. XLV, fig. 151. — SowuRBY, Conch. 



Icon., XVL 1868. pi. Lxvii, p. 339. 

 Margaron fUnio) zvynegungcvnsis Lka, Syn., 1870, p. 50. 

 Parreysia wynegn'ngcensis Simpson, Syn., 1900, p. 842. 



More elongated, generally a little less inflated and darker 

 colored than corrngata. The form is quite variable, subrhom- 

 boid to almost evenly elliptical. The variety la-i'irostris of 

 corrngata approaches it, but is diffcrentlv colored. 



Parreysia favidens (Benson). 



Shell rather large, heavy, somewhat inflated, irregularly ellip- 

 tical or ovate, inequilateral ; beaks high, full and large, sculp- 

 tured with strong, zigzag-radial ridges, which usually do not 

 extend on to the disk ; posterior ridge well marked ; narrowly 

 rounded or subangulate, ending about on the median line in a 

 blunt point ; there is often a low, radial central elevation ex- 

 tending to the base of the shell, which is slightly produced 

 where it ends; surface with strong, irregular growth lines, 

 sometimes concentrically sculptured ; epidermis tawny or 

 brownish, sometimes banded with green, covered when fresh 

 with a grayish bloom, occasionally feebly rayed ; pseudocardi- 

 nals strong and very much split up; there are often small tu- 

 bercles behind them; laterals two in the left valve, with often 

 a vestigial third one, double in the right valve, club-shaped ; 

 beak cavities deep ; muscle scars impressed ; nacre yellow-sal- 

 mon, or white. 



Length 70, height 50, diam. 33 mm. 



India. 

 ? Mya spuria Wood, Ind. Test.. 1825, p. 12, pi. it, fig. 35a. 



