These facts teach us, that though the birds of this group have evidently been derived mainly from New Guinea, yet the immigration has not been a recent one, since there has been time for the greater portion of the species to have become changed.

We find, also, that many very characteristic New Guinea forms lave not entered the Moluccas at all, while others found in Ceram and Gilolo do not extend so far west as Bouru.

Considering, further, the absence of most of the New Guinea mammals from the Moluccas, we are led to the conclusion that these islands are not fragments which have been separated from New Guinea, but form a distinct insular region, which has been upheaved independently at a rather remote epoch, and during all the mutations it has undergone has been constantly receiving immigrants from that great and productive island.

The considerable length of time the Moluccas have remained isolated is further indicated by the occurrence of two peculiar genera of birds, Semioptera and Lycocorax, which are found nowhere else.
We are able to divide this small archipelago into two well marked groups--that of Ceram, including also Bouru.

Amboyna, Banda, and Ke; and that of Gilolo, including Morty, Batchian, Obi, Ternate, and other small islands.