THYSUNTO 1065 



Physunio crosski ( Deshayes and Julien). 



Shell irregularly obovate, thin, inequilateral, scarcely in- 

 flated : beaks moderately full, acute, sculptured with rather 

 regular, suhradial ridges, which unite along a median line to 

 form a chevron-shaped pattern ; anterior end rounded, nar- 

 rowed, angled above; base line straight, very full behind the 

 middle ; hinge line a little sinuous, the hinder end produced 

 into a small wing; posterior end obliquely truncate above, bi- 

 angulate on the median line; surface delicately, concentrically 

 sculptured ; dorsal slope with subradial plications ; epidermis 

 fuscous-yellowish ; teeth delicate, much compressed ; nacre 

 flesh-colored, iridescent. 



Length 35. height 22, diam. 13 mm. 



Cambodia ; Cochin China. 

 Unio crossci Deshayes and Juuen, N. Arch. Mus., X, 1874, 



p. 124, pi. VI, flgs. $-"/. 

 Physunio crossci Simpson, S.vn., 1900, p. 831. 

 Contradcns crossci Haas, Conch. Cab., Unio, 1912, pi. 20, figs. 



1-3- 



If the specimen described and figured by Deshayes is adult 

 the species is much smaller and much less inflated than either 

 graindus or supcrhihs. The beak sculpture is figured and con- 

 sists of beautifully regular, subradial bars, which meet on a 

 median line and form a sharply pointed chev^ron-shaped pat- 

 tern. 



Physunio micropterus (Morelet). 



Shell subrhomboid, subinflated, inequilateral, rather thin ; 

 beaks full and high ; anterior end narrowed and rounded, 

 scarcely angulate above ; base line lightly curved, slightly fuller 

 behind the middle; dorsal outline curved, carried up behind 

 into a small wing ; dorsal slope obliquely subtruncate behind ; 

 posterior ridge full, rounded, ending in a rounded point near 

 the base of the shell ; surface with very fine, concentric sculp- 

 ture and a few wrinkles ; epidermis greenish-olive, subshining ; 



