69 



SCIENTIFIC RESULTS FROM THE MAMMAL SURVEY 



No. XVIII. 

 Beport on the House Rats of India, Burma, and Ceylon. 



BY 



Martin A. C. Hinton. 



At the request of the Bombay Natural History Society, I under- 

 took the comparison of the House Rats collected by the Mammal 

 Survey with the Indian material in the British Museum. The 

 work proved to be a complex and dithcvilt task, but I have now 

 reached three chief conclusions, namely : — (1) That the common 

 Indian House Rat, which in the various Survey Reports has been 

 listed either as " Epimys rufescens'^ or else as " i\ rvfesc-ns, var. 

 with white underparts," is indistinguishable specifically from 

 Rattus * rattus, Linnaeus ; (2) that this species shows in India, 

 Burma and Ceylon, a definite geographical variation, so that many 

 races or subspecies have now to be recognized ; and (3) that the 

 forms described as B. nitidus and R. vicerex, about the status of 

 which there has been much controversy, are entitled to full 

 specific rank, although they, too, are members of the B. rattus 

 group. 



In this paper R. rattus, as represented in the Mammal Survey 

 collections, is dealt with exhaustivelv ; and R. nitidus receives sufli- 

 cient treatment to enable me to define a very interesting sub- 

 species from the Chin Hills. With regard to R. vicerex, I must 

 for the present content myself with publishing some skull measure- 

 ments. 



In presenting my results to the Society I am fully conscious of 

 the fact that there is still plenty of room for further woik upon 

 these very difficult and somewhat unattractive animals. To obtain 

 definite results one needs long series of careiul measurements, 

 external and cranial, accompanied by careiul notes on the colour 

 and mammae, from as many districts as possible. As a basis for 

 further research I have given my original tables of skull measure- 

 ments, with a description of the method of making them, at the 

 end of this paper. If observers, dwelling in comparatively remote 



1 As pointed out by Hollister (P. Biol. Soc. Washington, XXIX, p. 126, 1916), 

 Rattus (misprinted Ruttus), Fischer {Das National Mtisemn der Naturgeschichte zu 

 Paris. Frankfurt au Main. 1803, Bd. II, p. 128), is a valid generic name and mu.st 

 replace Epimys, Trouessart (1880). This is unfortunate but quite uoavoidablo. 

 I would take this opportunity of expressing- my agreement v.ith Thomas's state- 

 ment that Fischer took R. rattus as the type of his genus, and not " decumarms " 

 (norvegicus) as asserted by Hollister. 



