CHAP. XIII. ] THE AUSTRALIAN REGION. 437 
finding the country already fairly stocked, comparatively few 
groups were able to establish themselves. 
Going back a little farther, we come to the entrance of those 
few birds and insects which belong to India or Indo-China ; and 
this probably occurred at the same time as that continental 
extension southward, which we found was required to account for 
a similar phenomenon in Java. Celebes, being more remote, 
received only a few stragglers. We have now to go much 
farther back, to the time when the ancestors of the peculiar 
Celebesian genera entered the country, and here our conjectures 
must necessarily be less defined. 
On the Australian side we have to account for Megacephalon, 
and the other genera of purely Papuan type. It may perhaps 
be sufficient to say, that we do not yet know that these genera, 
or some very close allies, do not still exist in New Guinea; in 
which case they may well have entered at the same time with 
the species, already referred to. If, on the other hand, they are 
really as isolated as they appear to be, they represent an earlier 
communication, either by an approximation of the two islands 
_ over the space now occupied by the Moluccas; or, what is per- 
haps more probable, through a former extension of the Moluccas, 
which have since undergone so much subsidence, as to lead to 
the extinction of a large proportion of their ancient fauna. 
The wide-spread volcanic action, and especially the prevalence of 
raised coral-reefs in almost all the islands, render this last 
supposition very probable. 
On the Oriental side the difficulty is greater; for here we find, 
what seem to be clear indications of a connection with Africa, as 
well as with Continental Asia, at some immensely remote epoch. 
Cynopithecus, Babirusa, and Anoa ; Ceycopsis, Streptocitta, and Gaz- 
zola (s. g.), and perhaps Sczsstrostrum, may be well explained as 
descendants of ancestral types in their respective groups, which 
also gave rise to the special forms of Africa on the one hand, and of 
Asia on the other. For this immigration we must suppose, that at 
a period before the formation of the present Indo-Malay Islands, 
a great tract of land extended in a north-westerly direction, till 
it met the old Asiatic continent. This may have been before 
