226 NATURAL HISTORY OF THE [chap. ix. 



recently separated from it ; for the adjacent district of 

 Palembang is new land, being a great alluvial swamp 

 formed by torrents from the mountains a hundred miles 

 distant. Banca, on the other hand, agrees with Malacca, 

 Singapore, and the intervening island of Lingen, in being 

 formed of granite and laterite ; and these have all most 

 likely once formed an extension of the Malay peninsula. 

 As the rivers of Borneo and Sumatra have been for acjes 

 filling up the intervening sea, we may be sure that its 

 depth has recently been greater, and it is very probable 

 that those large islands were never directly connected with 

 each other except through the Malay peninsula. At that 

 period the same species of squirrel and Pitta may have 

 inhabited all these countries ; but when the subterranean 

 disturbances occurred which led to the elevation of the 

 volcanoes of Sumatra, the small island of Banca may have 

 been separated first, and its productions being thus isolated 

 might be gradually modified before the separation of the 

 larger islands had been completed. As the southern part of 

 Sumatra extended eastward and formed the narrow straits 

 of Banca, many birds and insects and some Mammalia 

 would cross from one to the other, and thus produce a 

 general similarity of productions, while a few of the older 

 inhabitants remained, to reveal by their distinct forms their 

 different origin. Unless we suppose some such changes 

 in physical geography to have occurred, the presence of 



