176 UNIOKLD.E. 



The above description may be amplified by that given by 

 Sowerby in the Conchologia Iconica ':" Shell oblong-ovate, 

 thin, very smooth, somewhat inflated, covered with a blackish- 

 brown shining epidermis, pale iridescent-fawn within ; posterior 

 side roundly angular, produced, dorsal margin straight, lateral 

 margin oblique, end subacuminated, ventral margin raised towards 

 the end, very slightly contracted in the middle ; anterior side 

 short, narrow, dorsal margin slightly sloped, cuueate ; umboes 

 smooth." 



The following dimensions are taken from three adult specimens 

 in the collection of the Indian Museum : 



1. 2. 3. 



Long 51 50*5 52'5 mm. 



Lat ]00-5 95-25 95 mm. 



Diam 32 30 34 mm. 



The species is very widely distributed throughout India, Burma, 

 and Ceylon, and should Mousson's Unio evanescens prove to be 

 really a synonym, then Java must also be added to the above. 



Var. obesa (Hanley fy Theobald} ; Simpson, Washington, D.C., 

 Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 855. 



Umo marginalia var. obesa, H. & T., C. I. 1876, p. 20, pi. 43, fig. 3. 

 Unio corrianus, Sowerby, Conch. Icon, xvi, 1868, pi. 77, fig. 401. 



The variety is described as follows in the ' Conchologia Indica' 

 " A giant form, which does not exhibit the ochraceous band, and 



is peculiarly swollen The upper anterior tooth is almost 



linear ; the lateral [teeth] are not bent at the extremity, and the 

 upper one in the left valve is scarcely developed." 



The following dimensions are those of three specimens in the 

 Indian Museum. Those of No. 1 are of a specimen from Silchar 

 and those of Nos. 2 and 3 of specimens from Tonghoo : 



1. 2. 3. 



Long 67 64 57*5 mm. 



Lat 118 125 109 mm. 



Diam 48 44 43 mm. 



This inflated variety was originally noticed from the Irrawaddy 

 Eiver; there are, however, specimens in the collection of the 

 Indian Museum which undoubtedly belong to it from Chittagong, 

 Silchar and Toungoo, Burma. 



Var. tricolor (Klister^^ Simpson, "Washington, D.C., Smiths. 

 Inst., Nat. Mus. Proc. xxii, 1900, p. 855. 



Unio tricolor, Kiister, Conch. Cab., Unio, 1856, p. 156, pi. 45, 

 fig. 1 ; Jickeli, Faun. Moll. N.O.-Afr. 1874, p. 275 ; Pajtel, Conch. 

 Sam. iii, 1890, p. 170. 



