TRAPEZOIBEUS. 1^3 



Genus TRAPEZOIDEUS. 



Trapezoid eus, Simpson, Washington, D.C, Smiths. Inst., Nat. 

 Mus. Proc. xxii, p. 858. 



Type, Unio foUacea, Go\M ; Burma. 



liamje. Burma; Siam : Cambodia; Sumatra; Buiidelkund. 



Original (Zescrij^rioji:— 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- 

 centri1;ally sculptured, often having irregular radial ridges on the 

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

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

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

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

 valve with two ])seudocardinals and one lateral ; pseudocardinals 

 all irit'gular, 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 unkuown. 



318. Trapezoideus foliaceus {Gould). 



Tr(ii»-zoideus foUacem (tioiikl) ; Simpson, Wusbiugtou, D.C, 

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



Uitio foUacea, Gould, Proc. Bostou Sue. Nat. Hist, i, 1843, p. 141 ; 

 dtia Couch. 186i>, p. 191. ^ , ,, 



Unio foliaceus, Catlow & Reeve, Couch. Norn. 184o, P- 'J-|; 

 H ■& A. Adams, Gen. Rec. Moll, ii, 1857, p. 492; H. & 1., 

 C. I. 187(5, p. 19, pi. 42, tig. 3 ; Anderson, Yunnan Exp. 1877, 

 p. 900, pi. 80, tigs. 8-12 ; Poetel, Ci)uch. Sam. iii, 1890, p. 153. 



Man/aro7i {Unio) foliaceus, Lea, Syn. 1852, p. 39; 1870, p. 62 



Utiio pei/uemis, Authonv, Amer. Journ. Couch, i, 18(35, p. 3;jl, 

 pi. 25, tig. 2 ; Sowerby, Concii. Icon, xvi, 1868, pi. 95, fig. 619 ; 

 Pa^tell Conch. Sam. iil, 1890, p. 162. 



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



Oriyinal description :— Testa parva, coinpressa, fragili, fusco- 

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

 angulata; umbonibus parvis, subtilissime corrugatis ; dentibus 

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

 cente. 



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



HaL Tavoy. Represented in the Indian Museum by speci- 

 mens from Bbamo (Dr. J. Anderson), and Pegu ( IF. T. Blanford). 



Var. comptus {DesJiaijes 4' Jidlien); Simpson, AVashiugton, 

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



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

 1874, p. 120, pi. 6, figs. 3 & 4. 



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