MAMMALS 323 



with regard to the terrestrial, it is equally notable where the flying 

 mammals are concerned. 



The most noteworthy features of the fauna are the preponder- 

 ance of bats (i6 species) and rats (13 species) — which together 

 constitute nearly three-fourths of the total number of mammals 

 known to occur in the islands — and the absence of practically all 

 representatives of the ungulates, squirrels, carnivores, and flying 

 lemurs, which are characteristic of the surrounding regions and 

 abound on other islands at equal distance from the mainland. 

 From the Malayan islands where these occur they differ in that 

 "they are surrounded by water of relatively great depth, while 

 the others lie within the 50-fathom line. This paucity of mam- 

 malian life cannot be regarded as due to an unfavourable environ- 

 ment, since all the natural conditions on both Andamans and 

 Nicobars are perfectly suited to the support of a rich and varied 

 fauna " ; yet so great is it that it appears safe to assume that these, 

 " contrary to the case wnth the shallow-water islands, were isolated 

 at a time when the mammals now characteristic of the mainland 

 did not exist there." In fact, we are almost driven to conclude 

 that they never were at any time a portion of the continent, but 

 were formerly only far nearer to it, far larger and far more com- 

 pactly situated — a hypothesis that is further supported by an 

 investigation of the birds appertaining to them. 



" As yet no species have been discovered whose origin may be 

 referred to the remote period of a land connection : such mammals 

 as are now known are evidently of very recent origin, as in scarcely 

 an instance has their differentiation progressed further than in the 

 case of members of the same genera found on islands lying in 

 shallow water. The question at once arises, therefore, as to the 

 means by which they have arrived where they now are. Flights 

 from the mainland would readily account for the distribution of 

 the bats ; but the presence of the other mammals seems impossible 

 to explain otherwise than through the agency of man. With the 

 single exception of Tiipai nicobarica* all are types well known to 



* " It is worthy of note that this animal differs more conspicuously from its 

 congeners than is the case with any of the other mammals." But even it — 



