t^^l

176 UNioxiD.i.
The above description may be amplified by that given by
Sowerby in the ' Conchologia Icoiiica ':—"Shell oblong-ovate,
thin, very smooth, somewhat inflated, covered with a blackishbrown
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, cnneate; 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 ram.
Lat 100-5 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 ^ Theobald); Simpson, Washington, D.C,
Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 855.
Unio marginalis var. obesa, H. & T., 0. I. 1876, p. 20, pi. 43, fi