Tre Records of the Indian Museum. [Vom vs 
We can only speculate as to how this state of things came 
about. At the present day Naini Tal is a large cantonment lying 
among the Himalayas at an altitude of 6,500 feet ; it communicates 
with the plains by a cart road about 30 miles in length ; it con- 
tains some hundreds of well-built houses. ‘The principal masses 
of buildings are the north and south bazaars, which are situated 
at either end of a lake. The lake is surrounded on all sides, except 
at its southern end, where it overflows toward the plains, by a 
circle of hills, the highest points of which, such as Cheena and 
Ayapata, are more than 1,000 feet above the level of thelake. Upon 
the inner slopes of these hills most of the larger houses are situated. 
Without detailed reference to the history of Naini Tal we may 
say briefly that practically the whole cantonment has come into 
being within the last hundred years. A century ago there was prob- 
ably a small hamlet or two on the shores of the lake, the inhabi- 
tants of which held very occasional intercourse with the plainsmen. 
The rat population of Naini has grown to its present condition 
in even measure with the growth of the town. If we speculate 
as to how they came to be as we find them, we may perhaps be 
inclined to some such explanation as the following. The white- 
tailed: race are the original inhabitants, but the black-tailed rats 
are invaders from the plains which have established themselves 
in the central parts of the town and forced the others to occupy 
the more distant outlying houses. It may be supposed that the 
daily arrival of carts carrying stores from the plains is sufficient to 
explain how the supposed invasion was effected. In my opinion 
however this invasion hypothesis may be rejected for the following 
reasons :—Both classes of the Naini rats resemble one another 
and differ from the lowland rats in the quality of their fur and in 
having shorter tails. The two classes of Naini rats differ from one 
another as classes in the colour of the tail only and in no other res- 
pect. Individual specimens of either class might be captured and 
produced as evidence to show that this is an erroneous statement, 
but an inspection of even as few as ten of each class would, I feel 
sure, convince most people that this statement is correct. The 
essential facts of the case as they appear to me are as follows .— 
' (1) There are, living in the same limited area apparently 
under the same conditions, two classes of animals 
which differ from one another in one obvious character 
only. 
(2) These two classes are segregative, 7.e 
from one another. 
they live apart 
5) 
If we enquire as to how this state of affairs came about, we 
shall best find the answer by considering the case of the white- 
bellied rats of Poona which differ from the common rats of that 
place in one character only (albiventralism) and are found apart 
from the common rats. 
1 See The Zoologist, (3), xv, p. 1, January 1801. 
