194 UNioyin.TT. 



Unio frar/iU'ii, Nevill, J. A. S. B. xlvi, 1877, p. '59; Anderson, 

 Yiinuan Exp. 1877, p. 400, pi. 80, figs. 8-12. 



Ori(/iual (Jcscniition ; — Te.sta obloiiga^ transversa, compres.sa, 

 tenui, fragili, ina-qiiilaterali, luteo-riibiginosa, ad apiceni decorti- 

 cata et striis granulosis divaricatis ornata ; urnbonibus minimis, 

 obtusis, vix proemiueiitibus ; latere antico obtuso, paulo angus- 

 tiori ; latere postico latiori, oblique truncate, striis numerosis, 

 subcEqualibns, arcuatis, ab angulo postico nascentibus ornato ; 

 margine cardinal! brevi, angusto, in valvula dextra dente cardinal! 

 mininio, obliquo, simplici, vix proeminenti, dente lateral! postico 

 elongate, angustissimo ; in altera -valvula dentibus cardinalibus 

 duobus, infequalissimus, divaricatis, dente postico angusto pro- 

 funde et angustissime biiido. 



Long. 18, lat. 32, diam. 10 mm. 



Hah. Cambodia. 



Var. zayleymanensis (Nevill, J//S.); Preston, Eec. Ind. Mus., 

 Calcutta, vii, 1912, p. 307. 



Original description: — Sbell thinner and smaller than the typical 

 form, moi'e produced anteriorly and much more obtuse posteriorly; 

 the slight curve in the ventral margin is also absent. 



Hab. Bliamo {Dr. J. Anderson) ; there are also specimens in the 

 Indian Musenm from Zayleyman (Anderson) and Ehamo. 



Type in the Indian Museum. 



319. Trapezoideus misellus (Moreld). 



Trapezoidcua >nise/h/s (Morelet) ; Simpson. A\'a.'<Iiiui;tou, D.C., 

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



Unio miseUii.'i, Morelet, Journ. de Conch., Paris, xiii,' 1865, p. 21 ; 

 Ser. Conch, iv, 1875, p. 341, pi. 14, tig. 2; Ppetel, Conch. Sam. 

 iii, 1890, p. 159. 



Unio siamensis, Lea, Proc. Acad. Nat. Sci. PhiUxdelphia, x, 1806, 

 p. l-io ; Journ. Acad. Nat. Sci. I'hiladelphia, vi, 1868. p. 279, 

 pi. 38, tio-. 93; Obs. (Jenus Unio, xii. 1869, p. 39, pi. 38, 

 fig. 93. 



Mm-garon [Unio) siamensis, Lea, Syn. 1870, p. 57. 



Original description : — Testa transversa, depressa, insequi- 

 lateralis, tenuis, epidermide lamelloso-striata, luteo-virenti, pro- 

 gressu temporis fuscescente, vestita ; margo anterior attenuatus, 

 posterior dilatatus, inferior medio sinnatus ; nmbones parvi, 

 depressi, acuti, plerumque decorticat! ; dens cardiualis lamelli- 

 formis, exilissimus, in adultis obsoletus ; lamella) in utraque valva 

 parvulse, simplices; testa interna ina^qualiter sulcata vel malieata; 

 margarita plumbea, squalida. snb urnbonibus late rubigineo tincta. 



Long. 28, lat. 61, diam. 16 mm. 



Hah. Siam. Eepreseuted in the Indian Museum by specimens 

 from. Tenasserim, and the Irrawaddy Eiver at Sagaing (J. i'oggin 

 Broivn). 



