32 Journal of the Asiatic Society of Bengal. [N.S., XVI, 
A. Shell less than 4 mm. long, with 2 
whorls; its mouth with narrow 
attenuated peristome, regularly 
oval or ovate, at least 1? times 
as high as broad yy. .. C. austeni. 
B. Shell at least 6 mm. long, with 34 
whorls; its mouth with a broad 
attenuated peristome, narrowly 
ovate, a little more than twice 
as hi bro . C. hiraser. 
C. Shell at least 8 mm. ‘long, with 4 
whorls; its mouth with an in- 
elongate than in the other phair C. terebra. 
II. Shell irregularly ovate, less than 3 times as high as 
broad, avec with strong, sometimes subspi- 
nose spiral line 
A. Shell. not more Pies 4°5 mm. long, 
gins; the mouth irregularly oval C. lineatum. 
B. Shel over 5 mm. long, with 4 
orls; the suture much less 
well defined and not so angular 
at the margins ; the mouth ovoid, 
narrowed above . C. subspinosum. 
ADDENDUM. 
Since this paper was written I have found Camptoceras 
lineatum living on the lower side of grass-stems in a small 
muddy channel of sluggish water running into the north end 
of the Loktak Lake in Manipur, Assam. 
The spiral lines on the shell are subspinose, but not so 
distinctly so as in C. subspinosum. 
The animal resembles that of Gyraulus except in possessing 
a curious epipodial siphon on the left side instead of a simple 
V-shaped process. The foot is narrowly tongue-shaped, blunt- 
ly pointed behind and not extending much beyond the apex 
of the mouth of the shell when fully expanded. The snout is 
broad and blunt. The tentacles are long, filiform and slight- 
ly ong : hie tgp ep they are somewhat expanded at the 
a Ww ternally they bear the small, black, sessile eyes 
the same 5 posite The mantle does not extend over the 
shell and has simple margins. On the left side the epipodial 
lobe arises posteriorly as a short, simple expanded ridge and 
then grows out into a relatively long, broad, leaf-like process, 
which can be folded spirally on itself in such a way as to form 
