218 NATURAL HISTORY OF THE [chap. ix. 



even European genera on the summits of the Javanese 

 mountains that we can prove the former connexion of that 

 island with the Asiatic continent. With land animals, how- 

 ever, the case is very different. Their means of passing a 

 wide expanse of sea are far more restricted. Their distri- 

 bution has been more accurately studied, and we possess 

 a much more complete knowledge of such groups as 

 mammals and birds in most of the islands, than we do of 

 the plants. It is these two classes which will supply us 

 with most of our facts as to the geographical distribution 

 of organized beings in this region. 



The number of Mammalia known to inhabit the Indo- 

 Malay region is very considerable, exceeding 170 species. 

 With the exception of the bats, none of these have any 

 regular means of passing arms of the sea many miles in 

 extent, and a consideration of their distribution must 

 therefore greatly assist us in determining, whether these 

 islands have ever been connected with each other or with 

 the continent since the epoch of existing species. 



The Quadrumana or monkey tribe form one of the most 

 characteristic features of this region. Twenty-four dis- 

 tinct species are known to inhabit it, and these are distri- 

 buted with tolerable uniformity over the islands, nine 

 being found in Java, ten in the Malay peninsula, eleven in 

 Sumatra, and thirteen in Borneo. The great man-like 

 Orang-utans are found only in Sumatra and Borneo ; the 



