DESCRIPTIONS OF NEW SPECIES OF MAMMALS. 803 



SUMMARY. 



The mammal fauna of the Andaman and Nicobar islands is now known to 

 consist of 35 positively identified species and 4 others whose status is still in 

 doubt. 



On comparing this fauna with that of other islands in the Malay region, 

 two remarkable features are at once noticeable, the prevalence of bats and 

 rats and the absence of practically all of the charateristic Malayan types 

 such as ungulates, squirrels, carnivores, and flying lemurs, which abound on 

 other islands at an equal distance from the mainland. This paucity of 

 mammalian life cannot be regarded as due to unfavourable surroundings, 

 since all the natural conditions on both Andamans and Nicobars are perfectly 

 suited to the support of a rich and varied fauna. In only one feature do the 

 Andamans and Nicobars differ from such islands as Sumatra, Java, Borneo, 

 the Natunas, Anambas, and Tambelans ; they are surrounded by water of 

 relatively great depth, while the others lie within the 50-fathom line. Doubt- 

 less this greater depth of water indicates separation from the mainland 

 during a much longer period of time ; and it appears safe to assume, there- 

 fore, that the Andamans and Nicobars, contrary to the case with tbe shallow- 

 water islands, were isolated at a time when the mammals, now characteristic 

 of the Malay region, did not exist there. As yet no species are known whose 

 origin may be referred to the remote period of this land connection, but that 

 such exist; in the unexplored interior of the larger islands, particularly of the 

 Andaman group, is not beyond tbe limit of possibility. 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. Flight 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 Tupaia nicoharica^ all are types well known to be 

 closely associated with man throughout the Malayan region. Moreover, the 

 period of time necessary to the development of the peculiarities of the native 

 Andamanese would, undoubtedly, be ample to allow the formation of any of 

 the species known from either group of islands, since in a biologic sense it has 

 been vastly longer to the smaller, more rapidly breeding animals than to 

 man. The introduction, intentional or otherwise, of a pig, a monkey, a 

 palmcivet, two or three species of rats, a shrew and perhaps also a treeshrew, 

 at about the time when the various islands were peopled by their present 

 human inhabitants, would amply account for the existence of the present 

 mammal fauna with its striking peculiarities. 



^It is worthy of note that this animal differs more conspicuously from its congeners than is 

 the case with any of the other mammalB. 



