The geographical distribution of animals, with a study of the relations ...

chap, xiii.] THE AUSTRALIAN REGION. 437finding the country already fairly stocked, comparatively fewgroups were able to establish themselves.Going back a little farther, we come to the entrance of thosefew birds and insects which belong to India or Indo-China ;andthis probably occurred at the same time as that continentalextension southward, which we found was required to account fora similar phenomenon in Java. Celebes, being more remote,received only a few stragglers. We have now to go muchfarther back, to the time when the ancestors of the peculiarCelebesian genera entered the country, and here our conjecturesmust necessarily be less defined.On the Australian side we have to account for Megacephalon,and the other genera of purely Papuan type. It may perhapsbe sufficient to say, that we do not yet know that these genera,or some very close allies, do not still exist in New Guinea ; inwhich case they may well have entered at the same time withthe species, already referred to. If, on the other hand, they arereally as isolated as they appear to be, they representan earliercommunication, either by an approximation of the two islandsover the space now occupied by the Moluccas ; or, what is perhapsmore probable, through a former extension of the Moluccas,which have since undergone so much subsidence, as to lead tothe extinction of a large proportion of their ancient fauna.The wide-spread volcanic action, and especially the prevalence ofraised coral-reefs in almost all the islands, render this lastsupposition 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, aswell as with Continental Asia, at some immensely remote epoch.Cynopithecus, Babirusa, and Anoa; Ceijcopsis, Streptocitta, and Gazzola(s. g.), and perhaps Scissirostrum, may be well explained asdescendants of ancestral types intheir respective groups, whichalso gave rise to the special forms of Africa on the one hand, and ofAsia on the other.For this immigration we must suppose, that ata period before the formation of the present Indo-Malay Islands,a great tract of land extended in anorth-westerly direction, tillit met the old Asiatic continent. This may have been before