KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 56. wN:0 2. 11 
In order to get a proper understanding of the Fauna of Further India and. espe- 
cially that one of Siam, it is necessary to give a short account of the geological condition 
of this continent at the earlier epoques. 
The present Fauna of the Oriental Region apparently has its origin from the epoque 
which has been called the Pliocen. During that period the Indian Peninsula, Further 
India and the Malay Archipelago constituted a large continent which has been called 
the Gondwana-continent. Australia and New Guinea were, however, already separated 
from that enormous continent and have therefore developed quite a peculiar Fauna of 
their own. 
The eastern part of the Gondwana-continent appears to have been divided into 
two different parts: one western with mountains of a type which have been called altaic 
and one southern with another type of mountain chains called sinic. 
Fig. 3. Almost impenetrable brush-jungle near Hat Sanuk. 
By and by the Fauna got highly developed, but then large parts of the continent 
started to sink and in such a way the Bay of Bengal was formed. Therefore the Fauna 
of the Indian Peninsula had to develop quite independent of the Fauna of Further India. 
In a later period large revolutions, principally volcanic, destroyed the connection between 
certain other parts of the Eastern continent and thus the Malay Archipelago was formed. 
The sinic mountains were gradually destroyed and then the transformation of the 
altaic mountain chains commenced. At that time a great depression occured which 
formed the Gulf of Siam. Borneo now became separated from Sumatra. Java, on the 
contrary, had probably already before that time been separated from the rest of the con- 
tinent which is indicated by the lack of several species which are to be found on the other 
Islands of the Malay Archipelago. The further east we go the poorer is the Fauna. This 
may possibly be due to unfavourable natural conditions at the same time as great vol- 
canic eruptions prevented the development of a rich Fauna. Another great depression 
