154 UNIONID^E. 



notata. Testa increment! lineis concentrice rugata, postice plicis 

 paucis raro notata et valde evaneseentibus. Dentibus minimis 

 ut in M. salweniana. Nacrea cserulescente, unibones versus 

 flavescente. 



Long. 52, lat. 96, diam. 28 mm. 



Hob. Near Mandalay. 



Allied to P. salwenianus, but differing from that species in its 

 more elongate form and smoother surface ; young specimens 

 occasionally show traces of sculpture on the posterior slope, but 

 this character disappears when adult. 



Genus PARREYSIA. 



Parreysia, Conrad, Proc. Acad. Nat. Sci. Philadelphia, vi, 1853, 

 p. 267 ; Simpson, Proc. Acad. Nat. Sci. Philadelphia, xxii, 1900, 

 p. 840. 



TYPE, Unio multidentatus, Philippi. Said to come from 

 Australia but probably an Indian shell. 



Range. India ; Burma ; Indo-China ; China. 



Shell solid, inflated, oval to subrhomboid, with full, high, zigzag, 

 radially sculptured beaks, the sculpture often extending over the 

 disk ; epidermis smooth and bright, sometimes a little rayed, with 

 two irregular pseudocardinals in the left valve which are more or 

 less broken into ragged denticles or are strongly, vertically striate, 

 and two laterals, the lower the larger; right valve with one, 

 sometimes two pseudocardinals, the upper small, compressed, and 

 a few tubercles behind them, with two laterals, the upper the 

 larger ; cavity of the beaks rather deep, not compressed ; dorsal 

 scars under the hinge, not visible ; the two upper anterior muscle 

 scars very deep, confluent, the lower linear ; nacre white to 

 salmon, iridescent behind. 



Animal unknown. 



Conrad's name appears to be a nomen nudum and Simpson's 

 description is therefore that given above. 



Subgenus PARREYSIA (sensu stricto). 

 Parreysia, Conrad, 1853. 



.For type, range and characters see description of genus above. 



290. Parreysia (Parreysia) corrugata (Miiller). . 



Parreysia (Parreysia) corruqata (Miiller) ; Simpson, Washington, 

 D.C., Smiths. Inst, Nat. Mus. Proc. xxii, 1900, p. 841. 



Mya corrugata, Miiller, Verm. Terr, et Fluv. 1774, pt. 2, p. 214 ; 

 Besch. Ges. Berl. iv, 1779, p. 56, pi. 36, figs. 7, 8; Gmelin, Syst. 

 Nat. 13th ed. 1788, p. 3221; Schroter, Flussconch. 1779, 

 p. 181, pi. 9, fig. 3 ; Wood, Gen. Conch, i, 1815, p. 108, pi. 24, 

 figs. 1-3; Dillwyn, Cat. i, 1817, p. 52; Mawe, Linn. Conch. 

 1823, pi. 4, fig. 3 ; Wood, Ind. Test. 1825, p. 12, pi. 2, fig. 31 a ; 

 1856, rev. ed. p. 16, pi. 2, fig. 31. 



