I 184 TRAPEZOIDEUS 



straight or even somewhat convex, frequently there is a beauti- 

 full dark green ray on the forward part of the posterior slope. 



Length 45, height at beaks 23, at postero-dorsal angle 24, 

 diam. 15 mm. Beaks situated at 1-3 of the length." (von 

 Martens). 



Type locality, Chindwin River near Kalewa and Matu and 

 in the Trriwadi near Yenangyoung, Burmah. 

 Unio miscelliis var. sitbclatlinitus von Martens, Arch, fiir 



Naturg., I, 1899, p. 44, pi. VI, fig. 3. 

 Trapesoideus subclathratus Haas, Conch. Cab., Unio, 1912, pi. 



33. %• 6. 

 Trapezoideus paleEGOIxi (Sowerby). 



Shell decidedly rhomboid or trapezoid, much wider behind 

 than in front, compressed inequilateral ; beaks rather full ; 

 posterior ridge prominent, narrowly rounded, ending near the 

 base of the shell in a rounded point ; dorsal line nearly straight ; 

 posterior and almost squarely truncate ; anterior end narrowed, 

 rounded above, cut away below ; base line incurved in the 

 middle ; surface with well marked, concentric wrinkles, with 

 a few nearly vertical, curved folds in front of the posterior 

 ridge ; epidermis greenish-yellow. 



Length 70, height at beaks 28, at hinder end of ligament 35 

 mm. 



Siam ; Cambodia. 

 Anodon pallegoixi Sowercy, Conch. Icon., XVII, 1867, pi. 



VIII, fig. 17. — Haas, Conch. Cab. Unio, 1912, pi. 33, figs. 3-5. 

 Anodonta pallegoixi Ci.essin, Conch. Cab. Ano., 1876, p. 210, 



pi. LXIV, fig. 6. 

 Trapesoideus pallegoixi Simpson, Syn., 1900, p. 859. 



Sowerby tells nothing of the teeth or nacre of this shell, it 

 is probable that the teeth are lamellar and rather feebly devel- 

 oped. It is plainly a number of the Trapecoideus group of 

 Uniones and dififers from foliaeeiis and uiiscellns in the de- 

 cidedly trapezoid form and in having nearly vertical curved 

 plications in front of the posterior ridge. 



Haas, (1. c), considers this a synonym of T. misellus. 



