194 



Unio fraqilis, Nevill, J. A. S. B. xlvi, 1877, p. 39; Anderson, 

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



Original description : Testa oblonga, trausversa, compressa, 

 tenui, fragili, inequilateral!, luteo-rubiginosa, ad apicem decorti- 

 cata et striis granulosis divaricatis ornata; umbonibus minimis, 

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

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

 sub^qualibus, arcuatis, ab angulo postico nascentibus ornato ; 

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

 ruinimo, obliquo, simplici, vix preeminent], dente lateral! postico 

 elongate, angustissimo ; in altera valvula dentibus cardinalibus 

 duobus, iniequalissimus, divaricatis, dente postico angusto pro- 

 funde et angustissime bifido. 



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



Hab. Cambodia. 



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

 Calcutta, vii, 1912, p. 307. 



Original description : Shell thinner and smaller than the typical 

 form, more produced anteriorly and much more obtuse posteriorly; 

 the slight curve in the ventral margin is also absent. 



Hab. Bhamo (Dr. J. Anderson) ; there are also specimens in the 

 Indian Museum from Zayleyman (Anderson) and Bhamo. 



Type in the Indian Museum. 



319. Trapezoideus misellus (Morelet). 



Trapezoideus misellus (Morelet) ; Simpson. Washington, D.C. ? 



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

 Unio misellus, Morelet, Journ. de Conch., Paris, xiii, 1865, p. 21 ; 



Ser. Conch, iv, 1875, p. 341, pi. 14, fig. 2; Psetel, Conch. Sam. 



iii, 1890, p. 159. 

 Unio swmensis, Lea, Proc. Acad. Nat. Sci. Philadelphia, x, 1866, 



p. 133 ; Journ. Acad. Nat. Sci. Philadelphia, vi, 1808, p. 279, 



pi. 38, fig. 93 ; Obs. Genus Unio, xii, 1869, p. 39, pi. 38, 



fig. 93. 

 Margaron ( Unio) siamensis, Lea, Syn. 1870, p. 57. 



Original description : Testa transversa, depressa, inaequi- 

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

 gressu temporis fuscescente, vestita ; margo anterior attenuatus, 

 posterior dilatatus, inferior medio sinuatus ; umbones parvi, 

 depressi. acuti, plerumque decorticati ; dens cardinalis lamelli- 

 formis, exilissinius, in adultis obsoletus ; lamellae in utraque valva 

 parvulaa, simplices; testa interna inaequaliter sulcata vel malleata; 

 margarita plumbea, squalida, sub umbonibus late rubigineo tincta. 



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



Hab. Siam. Represented in the Indian Museum by specimens 

 from Tenasserim, and the Irrawaddy River at Sagaing (J. Cogyin 

 Brown). 



