we can draw a line among the islands, which shall so divide them that
one-half shall truly belong to Asia, while the other shall no less
certainly be allied to Australia. I term these respectively the
Indo-Malayan and the Austro-Malayan divisions of the Archipelago.
On referring to pages 12, 13, and 36 of Mr. Earl's pamphlet, it will be
seen that he maintains the former connection of Asia and Australia as
an important part of his view; whereas, I dwell mainly on their
long continued separation. Notwithstanding this and other important
differences between us, to him undoubtedly belongs the merit of first
indicating the division of the Archipelago into an Australian and an
Asiatic region, which it has been my good fortune to establish by more
detailed observations.
Contrasts in Natural Productions.--To understand the importance of this
class of facts, and its bearing upon the former distribution of land and
sea, it is necessary to consider the results arrived at by geologists
and naturalists in other parts of the world.
It is now generally admitted that the present distribution of living
things on the surface of the earth is mainly the result of the last
series of changes that it has undergone. Geology teaches us that
the surface of the land, and the distribution of land and water, is
everywhere slowly changing. It further teaches us that the forms of life
which inhabit that surface have, during every period of which we possess
any record, been also slowly changing.
It is not now necessary to say anything about how either of those
changes took place; as to that, opinions may differ; but as to the fact
that the changes themselves have occurred, from the earliest geological
ages down to the present day, and are still going on, there is no
difference of opinion. Every successive stratum of sedimentary rock,
sand, or gravel, is a proof that changes of level have taken place; and
the different species of animals and plants, whose remains are found
in these deposits, prove that corresponding changes did occur in the
organic world.
Taking, therefore, these two series of changes for granted, most of the
present peculiarities and anomalies in the distribution of species may
be directly traced to them. In our own islands, with a very few trifling
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