IgI0. | R. E. Luoyp: The Races of Indian Rats. 13 
If we examine the two classes of Naini rats strictly from the 
point of view afforded by the theory of gametic factors, we must 
suppose that the Ayapata class are not all exactly alike in their 
gametic constitution. For example, among the twenty-seven rats 
of this class, which have been caught, are two specimens in which 
the dorsal pigment of the tail extends to the tip. These are, as 
regards tail coloration, exactly like the well-known species Mus 
vicerex of Kashmir and several other species of other places. I 
have had the opportunity of examining at least twenty specimens 
of M. vicerex. ‘The tails of all of them are exactly like these parti- 
cular two of the Ayapata race. If we are to explain the facts in 
terms of the theory, we must suppose that these two differ from 
the others of the Ayapata race but resemble the rats of Kashmir 
as regards that part of their gametic constitution which determines 
the pigmentation of the tail. These two were caught along with 
others of the Ayapata race, and it is almost certain that they are 
closely related by birth to them (zbid., page 40). The tail of one 
of these rats is shown on plate ix (second from above). 
Comparison between Indian and English Rats. 
Through the kindness of the Curator of Zoology of the British 
Museum, I have had the opportunity of examining a brown and a 
black specimen of Mus rattus and a Mus decumanus which were 
caught in England. I can find no difference between them and 
Indian rats of the same species. 
In conclusion, I must express my great obligations to Captain 
J. Kunhardt, I.M.S., who was in charge of the Plague investigations 
at Poona, and also to Colonel A. E. Ward for his kind help during 
my visit to Naini Tal. 
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