OEOGEAPHY OF THE MALAY ARCHrPELAGO. 179 



countries is least, and vice versd. But again, the mass of the 

 species of Borneo, Java, &c., even when not identical are congeneric, 

 which, as before explained, indicates identity at an earlier epoch ; 

 whereas the great mass of the fauna of Celebes is widely different 

 from that of the western islands, consisting mostly of genera, and 

 even of entire families, altogether foreign to them. This clearly 

 points to a former total diversity of forms and species, — existing 

 similarities being the result of intermixture, the extreme facilities 

 for which we have pointed out. In the case of the great western 

 islands a former more complete identity is indicated, the present 

 differences having arisen from their isolation during a considerable 

 period, allowing time for that partial extinction and introduction 

 of species which is the regular course of nature. If the very small 

 number of western species in Celebes is all that the most favour- 

 able conditions for transmission could bring about, the complete 

 similarity of the faunas of the western islands could never (with 

 far less favourable conditions) have been produced by the same 

 means. And what other means can we conceive but the former 

 connexion of those islands with each other and with the continent 

 of Asia ? 



In striking confirmation of this view we have physical evidence 

 of a very interesting nature. These countries are in fact still 

 connected, and that so completely that an elevation of only 800 

 feet would nearly double the extent of tropical Asia. Over 

 the whole of the Java Sea, the Straits of Malacca, the Gulf of 

 Siam, and the southern part of the China Sea, ships can anchor in 

 less than fifty fathoms. A vast submarine plain unites together 

 the apparently disjointed parts of the Indian zoological region, and 

 abruptly terminates, exactly at its limits, in an unfathomable ocean. 

 The deep sea of the Moluccas comes up to the very coasts of 

 Northern Borneo, to the Strait of Lombock in the south, and to 

 near the middle of the Strait of Macassar. May we not therefore 

 from these facts very fairly conclude that, according to the system 

 of alternate bands of elevation and depression that seems very 

 generally to prevail, the last great rising movement of the volcanic 

 range of Java and Sumatra was accompanied by the depression 

 that now separates them from Borneo and from the continent ? 



It is worthy of remark that the various islands of the Moluccas, 

 though generally divided by a less extent df sea, have fewer species 

 in common ; but the separating seas are in almost every case of 

 immense depth, indicating that the separation took place at a much 

 earlier period. The same principle is well illustrated by the dis- 



12* 



