1861.] 
Contributions to Indian Malacology. 
365 
Hilg'. 
Kolam. 
Patch. 
Kali-. 
Shev. 
Nilgiri Hills, 
— 
6 
3 
5 
6 
Kolamullay Hills, 
6 
— 
3 
— 
3 
Patchamulluy Hills, ... 
3 
3 
— 
4 
1 
Kalryenmullay Hills, .. 
5 
2 
4 
— 
1? 
Shevroy Hills, 
6 
3 
1 
1 ? 
— 
The most interesting circumstance connected with these col- 
lections, is the evidence they afford of an uniform fauna, (though 
with some slight specific distinctions, as in the case of Alyceeus, 
Diplommatina, Cyclotus, Streptaxis &c.) upon the higher portions 
of the various detached groups of hills with more or less flat 
tops, which are scattered over the plains of Southern India. So 
much is this the case, that we have found II Nilagrica, Pfr. and II. 
Maderaspatana ,* Gray near Chettycolum, N. of Triohinopcdy, upon 
the upper portion of a detached peak, which cannot he above 1500 
feet in height. 
It is not at all probable these shells, all inhabitants of a compara- 
tively moist and cool climate, should have been able to cross the hot 
dry plains which at present extend between the several groups of 
hills. But as all geological evidence clearly proves the compara- 
tively recent elevation of the plains of the Indian peninsula, we can 
readily conceive, that in a recent geological epoch the whole of 
them were under water, and the occasional migration of living speci- 
mens on floating wood from island to island may easily have taken 
place in the manner suggested by Darwin : [On the origin of species, 
p. 397,] or we may suppose that, moisture being more influential in 
determining the range of the pulmoniferous mollusca than slight 
differences of temperature, and the elevation of the country having 
been extremely slow, those portions of the low country which were first 
elevated above the sea, enjoyed for a time a moister climate than ob- 
tains, now that a wide extent of country intervenes between the opposite 
coasts : and thus that migration took place across these tracts, the 
* IT. maderaspatana is stated in Pfeiffer’s Mon. Helie, vol. i. p. 63, to occur 
around Pondicherry, Maderaspatam (a locality perhaps somewhat more widely 
known as Madras,) and Mangalore. It may occur on the Western Ghats in the 
vicinity of the last named town, but we do not hesitate to express our disbelief 
in its occurrence within 60 miles of either Madras or Pondicherry. Hie shell 
is probably common to all the high table lands and hill groups of Southern 
India, and occurs on the Isilgiris, in Mysore, the VVynaad and probably along 
the Western Ghats. 
