
1865.] Contributions to Indian Malacology. 69 
mouth. Aperture oblique, lunate, the breadth double the height, 
columella furnished with a spiral lamina which runs throughout the 
whorls, and renders the shell opaque around the umbilical excavation. 
Peristome simple, very slightly thickened inside, arcuate at the base 
of the right margin ; margins distant, the columellar oblique. 
Millem. inch, 
Major diameter,............s0cse 10 0.4 
(MiiniGriditifo;. ; siyetelsos. dsmeces vl 9 0.36 
es Cnr 3 nets 7 0.28 
Aperture 4 millem. broad, 2 high. 
Animal small with a very narrow foot, a very small mucus pore at 
the end, and a small lobe above. 
Habitat—Arakan hills near Prome; more abundant on the Arakan 
than on the Pegu side. 
This very pretty little snail, which is nowhere common, is re- 
markable for the screw like lamina on the columella, running up 
throughout the whorls. The indentation on the base of the lowest 
whorl is also peculiar; it varies considerably in position and form, 
being sometimes double, but it is almost always present. The animal 
bears a great resemblance to that of Nanina pylaica, Bs. 
The subgenus Sesara was founded by Albers for Nanina infrendens, 
Gould, (supposed at first to be a Helvx, ) a peculiar little Molmein shell 
with teeth inside the peristome. I have no hesitation in uniting to 
this species, besides the closely allied N. capessens, Bens., the T’ridopsis- 
like N. pylaica, Bs, and the present species, as well as the two fol- 
lowing. N. pylaica, N. capessens, N. imfrendens, and the present 
species are all distinguished by peculiar additions to the peristome, 
and form together a well marked group, all being more or less 
depressly trochiform, horny, with closely wound narrow whorls, 
arcuately costulate above, and smooth beneath. 
N. helicifera was found rarely on the road between Prome and 
Tongoop, and somewhat further south. In the Bassein district it 
appears to be replaced by N. Basseznensis. 
6. N. MAMILLaRIs, n. sp. 
Shell minutely perforated, very depressly trochiform, suborbicular, 
thin, horny; finely, closely and arcuately costulated above, the costu- 
lations passing over the periphery ; smooth, shining, and radiately 
10 
