156 



versus eminentes subradiata ; rnargine dorsali vix declivi, antice 

 concavo ; margiDe ventral! convexo ; lunula distincta margarita 

 albida, dentibus cardinalibus validis, laciniatis, haud laminatis. 



Shell small, green, subventricose (but varying in shape from 

 elliptic to rounded oval), scarcely inequilateral, smooth, except 

 near the prominent beaks, which are adorned with somewhat 

 radiating, oblique, linear ridges ; dorsal edges not much sloping, 

 the front one concave ; ventral margin convex ; lunule well 

 marked, nacre nearly white, cardinal teeth strong, jagged, not 

 lamellar. 



No dimensions being given in either of the above descriptions 

 the following are taken from three specimens in the Indian 

 Museum collection ; No. 1 being a specimen from the Biver 

 Dukaree, and Nos. 2 & 3 from Ceylon : 



1. 2. 3. 



Long 32-5 24-5 2075 mm. 



Lat 42-75 36 28 mm. 



Diarn 19-25 17'5 14-25 mm. 



Var. fragilis, H. $ T., C. I. p. 21, pi. 45, fig. 4. 



Presumably a thin form. 

 Long. 29, lat. 41 mm. 



Var. Isevirostris (Benson} ; Simpson, Washington, D.C., Smiths. 

 Inst., Nat. Mus. Proc. xxii, 1900, p. 842. 



Unio lavirostris, Benson, A. M. N. II. x, 1862, pp. 191-192 ; 



Blanford, J. A. S. B. Calcutta, xxxv, 1862, p. 144. 

 Unio corrugatus, var. Icevirostris, H. & T., C. I. 1876, p. 21, pi. 44, 



tigs. 5-6. 



Original description : Testa transverse oblonga, subovata, valde 

 inaequilaterali, crassiuscula, medio subtumida, antice superne 

 breviter angulata, deinde ro tun data, postice superne sensim 

 convexe descendente ; demum rotundata, margine ventrali con- 

 vexiusculo ; disco Iseviusculo, concentrice leviter striato ; epi- 

 dermide olivaceo-viridi, fusco fasciata; umbonibus convexis, 

 decorticatis, obsolete radiato-sulcatis, apicibus prominentibus, 

 approximatis ; lunula, impressa, elliptica ; ligamento elongate ; 

 dentibus cardinalibus brevibus, crassiusculis, eroso-sulcatis, later- 

 alibus subobliquis, elongatiusculis, rectis, utriusque valvae duplic- 

 ibus ; margarita colore salmonis vix tincta. 



Long. 28, lat. 50, diam. 20 mm. 



Hob. Streams and ponds near Chunar above Benares ; repre- 

 sented in the Indian Museum collection by localized specimens 

 from the Chittagong Hills, Sudiya and Arrah. 



Benson's description is supplemented by a short note from 

 which the following quotation is taken : " It has two indistinctly 

 raised dark rays on the posterior slope. The gradually compressed 



