12 NILS GYLDENSTOLPE, ZOOLOGICAL RESULTS OF THE SWEDISH ZOOLOGICAL EXPEDITIONS TO SIAM. 



soon followed which destroyed the connection between Sumatra and the Malay Penin- 

 sula. Ceylon, which at the present time exhibits a Fauna which in several ways differs 

 from that one of the upper parts of the Indian Peninsula, had already been separated 

 probably at about the same time as Borneo. As a completion to the deveiopment it 

 seems as if the Bengal Sea is regressing, so that an exchange between the Fauna of the 

 Indian Peninsula and that one of the Malay Peninsula was made possible. 



On the Malay Peninsula the Malayan elements are predominant. This is especially 

 evident concerning the Mammalian Fauna which highly resembles that one of Sumatra. 

 There are, however, also several species which have had their origin in India and which 

 have migrated to the Malay Peninsula since the connection with Sumatra already was 

 destroyed. 



Towards the north the Malayan Fauna extends as far as Pegu. Southern Siarn and 

 Tenasserim constitute, however, territories in which the Fauna is of a decidedly mixed 

 origin. The Eastern parts of Further India, through which sinic mountain chains are 

 running, has a very peculiar Fauna, the chief character of which is the total absence of 

 several pure Malayan forms. These forms, however, occur again on the lower slopes of 

 the Himalayas and in Southern China. Further India and especially the Eastern parts 

 of the same are therefore to be considered as very important for the deveiopment of the 

 present Fauna which still continues. These parts then most probably constituted one 

 of the centres of distribution for the Malayan Fauna. Borneo and Sumatra seems to 

 have constituted another centre. These two centres were probably in connection with 

 each other though the connection was destroyed before the deveiopment was actually 

 completed. 



In course of time the Fauna of Further India spread out in every direction. 



Southern China and Northern Siarn are traversed by mountain chains running 

 in a northern-southern direction and the numerous valleys formed excellent routes for 

 the further distribution of the animals. Both Hainan and Formosa were at that time 

 united with the Chinese continent and on account of this these islands possess a Fauna 

 which in several respects still reminds of that of the mainland. 1 Even the Fauna of the 

 Indian Peninsula is strongly represented in Further India. 



From a Zoogeographical point of view I therefore divide Siarn into three different 

 regions: 1) the mountain region of Northern Siarn, 2) the lowlands of Northern and 

 Central Siarn and 3) Lower Siarn. 



When looking at the Fauna in the mountain regions of Northern Siarn one of the 

 most striking facts is the near affinity to the Fauna of the Himalayas, and several forms 

 characteristic to the Himalayas have also been found in Siarn. The mountains of the 

 Malay Peninsula which like a backbone are running down the whole Peninsula are 

 showing the same affinity though the Malayan forms predominate the further south 

 we reach. The mountains of the Malay Peninsula and those of Sumatra, Borneo, Java, 

 Hainan, Formosa and the Philippines are displaying a similar character though they 

 sometimes differ inter se on account of the different time at which these islands got sep- 



Vide: Kungl. Svenska Vetenskapsakademiens Handlingar. Bd. 50. N:o 8. 1913. 



