t^^l

156 UlflONIDJE.
versus eminentes subradiata; margins dorsali vix declivi, autice
concavo; margine ventrali convexo ; lunula distincta niargarita
albida, dentibus cardinalibus validis, laciniatis, baud laminatis.
Shell small, green, subventrieose (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 River
Dukaree, and Nos. 2 & 3 from Ceylon :—
1. 2. 3.
Long 32-6 24-5 20'75 mm.
Lat 42-75 36 28 mm.
Diam 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. laevirostris {Benson) ; Simpson, Washington, D.C., Smiths.
Inst., Nat. Mus. Proc. xxii, 1900, p. 842.
Unio IcBvirostris, Benson, A. M. N. II. x, 1862, pp. 191-192;
Blanford, J. A. S. B. Calcutta, xxxv, 1862, p. 144,
Unio corrugatus, var. Icevirostris, II. & T., C. I. 1876, p. 21, pi. 44,
ligs. 5-6.
Original description :—Testa transverse oblonga, subovata, valde
insequilaterali, crassiuscula, medio subtumida, autice superne
breviter angulata, deinde roLundata, postice superne sensim
convexe descendente; deraum rotundata, margine ventrali convexiusculo;
disco Iseviusculo, concentrice leviter striate; epidermide
olivaceo-viridi, fusco fasciata; vimbonibus convexis,
decorticatis, obsolete radiato-suleatis, apicibus prominentibus,
approximatis; lunula impressa, elliptica; ligamento elongate ;
dentibus cardinalibu^s brevibus, crassiusculis, eroso-sulcatis, lateralibus
subobliquis, elongatiusculis, rectis, utriusque valvse duplieibus;
margarita colore salmonis vix tincta.
Long. 28, lat. 50, diam. 20 mm.
Hah. Streams aiid ponds near Chuntir above Benares ; represented
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