350 



ISLAND LIFE. 



[part II. 



from a continent, yet separated from it by so shallow a sea. 

 Kecent changes of sea and land must have occurred here on a 

 grand scale, and this adds to the interest attaching to the study 

 of this large island. 



The internal geography of Borneo is somewhat peculiar. A 

 large portion of its surface is lowland, consisting of great alluvial 

 valleys which penetrate far into the interior ; while the moun- 

 tains except in the north, are of no great elevation, and there 

 are no extensive plateaux. A subsidence of 500 feet would allow 

 the sea to fill the great valleys of the Pontianak, Banjarmassing, 

 and Coti rivers, almost to the centre of the island, greatly reducing 

 its extent, and causing it to resemble in form the island of Celebes 

 to the east of it. 



In geological structure Borneo is thoroughly continental, 

 possessing formations of all ages, with basalt and crystalline 

 rocks, but no recent volcanoes. It possesses vast beds of coal of 

 Tertiary age ; and these, no less than the great extent of alluvial 

 deposits in its valleys, indicate great changes of level in recent 

 geological times. 



Having thus briefly indicated those physical features of Borneo 

 which are necessary for our inquiry, let us turn to the organic 

 world. 



Neither as regards this great island nor those which surround 

 it, have we the amount of detailed information in a convenient 

 form that is required for a full elucidation of its past history* 

 We have, however, a tolerable acquaintance with the two higher 

 groups — mammalia and birds, both of Borneo and of all the 

 surrounding countries, and to these alone will it be necessary to 

 refer in any detail. The most convenient course, and that which 

 will make the subject easiest for the reader, will be to give, 

 first, a connected sketch of what is known of the zoology of 

 Borneo itself, with' the main conclusions to which they point ; and 

 then to discuss the mutual relations of some of the adjacent 

 islands, and the series of geographical changes that seem required 

 to explain them. 



