SCIENTIFIC RESULTS FROM THE MAMMAL SURrEY. 67 



Coorg northwards along the Western Ghats in Mysore ; in the 

 Central Provinces and in Kathiawar, the white-bellied type is 

 present but accompanied by rats of the dark bellied type. In 

 Cutch, Palanpui', Gwalior, Nimar, Western Khandesh, Berars 

 and Bellary, only dark bellied I'ats were collected. Similar facts 

 were noted by Major Lloyd, and he tells us that of many thousands 

 examined from the Punjab only some few from three villages 

 in the Amritsar and Lahore districts were of the light bellied 

 type (Rec. Ind. Mus. Ill, p. 20). 



Such distributional facts viewed in gross appear at first sight to 

 afford the strongest possible evidence in support of the idea that 

 white bellied and dark bellied types belong to distinct subspecies if 

 not species. The initial object of my work, indeed, was to test such 

 a belief. 



Mr. Wroughton has already brought before the Society 

 (/. B. N. H. 8., Vol. XXIII, p. 474) the view that the white bellied 

 forms of R. rattus in India and Burma represent the primitive wild 

 form of the species ; and that the dark bellied types are parasites, the 

 darkening of the underparts, no less than the darkening of the back, 

 being the outward indication of domesticity or parasitism. In 

 support of this view, one ma}^ point to the general similarity of the 

 Indian white bellied forms to the wild race, E. r. frvgivorvs, of the 

 Mediterranean region ; to their wide distribution, both in the mount- 

 ains and in the plains, in India and Burma: and to the wild life 

 which many of them lead in the jungles. Further en investigating 

 these white bellied rats in detail, we find that they behave very 

 much as do normal wild mammals as regards geographical variation 

 and that it is therefore possible and comparatively eas}'^ to arrange 

 them in geogTaphical races or subspecies. 



With regard to the dark bellied rats the case is different. They 

 are largely resti'icted to districts possessing substantial houses ; they 

 are more frequently caught within doors and far le-s frequently in the 

 open. Close investigation of their structure leads to nothing but 

 confusion ; the variation is largely individual or colonial, and scarcely 

 at all geographical. In some districts, as in Kumaon, such rats 

 seem to have little or no connection with the white bellied forms; 

 in other places, they differ from their white bellied companions 

 merely in colour and to a trifling extent in skull — the ornnial differen- 

 ces being readily susceptible of a physiological explanation, as is 

 shown below in discussing the rats of the Central Provinces and 

 Kathiawar; finally, in still other districts, the difference is purely 

 one of colour and even that sometimes breaks down. One concludes 

 from this that the dark bellied rats are of diverse origin ; some seem 

 to have been produced, in the localities where they are now found, 

 from the local whit^ bellied race ; others have found their way to 

 their present habitations from other more or less remote districts of 



