TRAPEZOIDEUS. 193 



Genus TRAPEZOIDEUS. 



Trapezoideus, Simpson, Washington, D.C., Smiths. Inst., Nat. 

 Mus. Proc. xxii, p. 858. 



TYPE, Unio foliacea, Gould ; Burma. 



Range. Burma; Siam : Cambodia; Sumatra; Bundelkund. 



Original description: Shell trapezoid, much compressed, with 

 a low posterior ridge and but slightly raised though pointed 

 beaks, which seem to be sculptured with irregularly radial ridges 

 arranged in two imperfect chevron-shaped loops ; surface con- 

 centrically sculptured, often having irregular radial ridges on the 

 posterior slope ; epidermis yellowish -green or brownish, with two 

 or more green rays above the posterior ridge ; teeth compressed ; 

 two pseudocardinals in the left valve, one under the beak, the 

 other in front, often not well separated, and two laterals ; right 

 valve with two pseudocardinals and one lateral ; pseudocardinals 

 all irregular, often pitted and peculiarly dentellate ; laterals 

 granular, showing traces of vertical striation ; cavity of the beaks 

 rather deep, compressed; muscle scars shallow, anterior scars 

 separate ; nacre soft, creamy, yellowish in the beak cavities. 



Animal unknown. 



318. Trapezoideus foliaceus (Gould). 



Trapezoideus foliaceus (Gould) ; Simpson, Washington, D.C., 

 Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 858. 



Unio foliacea, Gould, Proc. Boston Soc. Nat. Hist, i, 1843, p. 141 ; 

 Otia Conch. 1862, p. 191. 



Unio foliaceus, Catlow & Reeve, Conch. Nom. 1845, p. 59; 

 H. & A. Adams, Gen. Rec. Moll, ii, 1857, p. 492; H. & T., 

 C. I. 1876, p. 19, pi. 42, fig. 3 ; Anderson, Yunnan Exp. 1877, 

 p. 900, pi. 80, figs. 8-12 ; Peetel, Conch. Sam. iii, 1890, p. 153. 



Margaron (Unio) foliaceus, Lea, Syn. 1852, p. 39; 1870, p. 62. 



Unio peyuensis, Anthony, Amer. Journ. Conch, i, 1865, p. 351, 

 pi. 25, fio-. 2 ; Sowerby, Conch. Icon, xvi, 1868, pi. 95, fig. 619 ; 

 Pffitel, Conch. Sam. iii, 1890, p. 162. 



Margaron (Unio) peguensis, Lea, Syn. 1870, p. 51. 



Original description : Testa parva, compressa, fragili, fusco- 

 virescente, inequilaterali, transverse oblongo-ovata, postice sub- 

 angulata ; umbonibus parvis, subtilissime corrtigatis ; dentibus 

 exilibus, rectis, ad marginem parallelis ; margarita livida, irides- 

 cente. 



Long. 22, lat. 41-5, diam. 12-75 mm. 



Hab. Tavoy. Represented in the Indian Museum by speci- 

 mens from Bhamo (Dr. J. Anderson), and Pegu (W. T. Blanford). 



Var. comptus (Deshayes # Jullien); Simpson, Washington, 

 D.C., Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 859. 



Unio comptus, Deshayes & Jullien, Nouv. Arch. Mus. Paris, x, 

 1874, p. 126, pi. 6, figs. 3 & 4. 



