1910. | R. E. Luoyp: The Races of Indian Rats. 107 
been recorded from the Philippines. Rats possessing this same 
character have lately been met with in three separate parts of India. 
The circumstances of their capture show that they were not wander- 
ing members of an established race, but sports which have suddenly 
appeared among the common whole-coloured rats. 
I have repeated the chief arguments of my last paper in a 
more decided manner: as it was said, perhaps with some truth, 
that they were indicated rather than expressed therein. Moreover, 
other observations have since been made which afford confirmation. 
These will now be dealt with. 
Observations made at Poona. 
These are of special importance because of their accuracy. 
Most of the rat-killing measures in India have been undertaken 
in order to prevent plague ; to destroy the animals in large num- 
bers has been the chief endeavour. But at Poona the destruction 
was carried out systematically by the Plague Commission, as an 
experiment. In the interval between the 26th May, 1908, and 
22nd May of the following year, 45,487 rats were caught in Poona. 
They were not purchased indiscriminately from the town folk, but 
were captured in the following manner: Every night a large 
number of traps were set in certain houses of the town; each 
trap was labelled with the address of the house in which it 
was placed; next morning the traps were examined and _ those 
containing rats, in all to the number of 100 or more, were taken 
to the laboratory. Each rat then became the subject of various 
observations, which were recorded in a serial register. The points 
observed were those which might help the Commission in its 
task, such as the number of fleas on each rat, the pathological con- 
dition of the rat, the state of pregnancy, etc. For the biologist, 
it is most fortunate that any peculiarity of the outward appearance 
of the rats, as well as the place of residence of each one of them, were 
included among the records. 
Case 1.—The house rats of Poona as a class have no special 
peculiarities ; they are on the average slightly smaller than the rats 
of Bombay and some other cities ; they are of the whole-coloured 
brown type, but are much less variable than those of Bombay City, 
where the black and the white-bellied varieties are comparatively 
common : indeed, they were almost of daily occurrence among the 
two or three hundred common rats which were being caught at that 
place. At Poona, however, among all the forty-five thousand rats 
which were caught during the year, there was not a single black one 
and there were only nineteen of the white-bellied variety. Of these 
nineteen I was able to obtain three, which were caught while I was 
at Poona. This was not due to chance, but to the fact that traps 
were specially set on my behalf in those houses from which white- 
bellied rats had previously been captured. 
The white-bellied rats of Poona are exactly like the common 
ones, except for the one peculiar character which renders them 
