1866. | Contributions to Indian Malacoloqy. 13% 
thick form, with strong lateral teeth. The first shell is subalate pos- 
teriorly, and the posterior margin is very bluntly biangulate, the 
anterior margin is rounded at the end, but the slope thence to the 
~ umbo is almost a right line ; the second shell is perfectly rounded both 
before and behind. The shell of which the interior is figured corre- 
sponds so ill with Miuller’s description, being neither rhombic nor 
thin, that it may certainly be neglected. The figure moreover is ill- 
executed. 
Lamarck’s description is a little different from Miller’s : “ Unio testa 
ovato-rhombed, tenwi, viridi, umbonibus rugosis, rugis undulato-flecuosis 
sublongitudinalibus. Of the variety a he adds testa viridis, pubis 
caring levigatd. His variety 6 is said to be the next species, U. 
PUGOSUS. 
The type shell in Mons. de la Serre’s cabinet in Paris, which, by 
the politeness of M. Chenu, the Curator, I was enabled to examine in 
1862, is a thin broadly ovate form with small teeth, and a well 
marked posterior wing. It measures 40 mm. from anterior to pos- 
terior margin, and 33 from the uinbo to the ventral margin, the latter 
diameter being thus much greater in proportion to the former than 
in Kister’s type. The valves are inequilateral and much _ broader 
behind than before, the anterior margin rounded, sloping away below 
to the ventral side; posterior margin bluntly biangulate, the two 
angles rather wide apart. The form is common in Southern India 
and Ceylon, and appears to have been generally accepted as the type. 
Both Lamarck’s and Chemnitz’s types are quite distinct from 
Benson’s U. favidens, which has been confounded with them. 
No. 2..-Unto rugosus, Gmelin. Rivers of Coromandel. 
Mya corrugata magna, Chemn. Conch. Cab. X. 346, Pl. 170, f. 1659. 
M. rugosa, Gmel. p. 3222, No. 32. 
Unio corrugata, [b.|, Lam. VI., 78, No. 34. 
Unio rugosus, Kiister, Mart. and Chem. p. 290, Pl. 97, f. 5. 
Both this and the preceding species probably inhabit the Cauvery or 
neighbouring streams. Kiister’s figure represents an elliptical sub- 
equilateral shell, with strong angulate sulcation at the umbones, 
extending to within no great distance of the ventral margin. Gmelin’s 
original description is the following :— 
