Of the
year (from March to November), blowing over the northern parts of
that country, produces a degree of heat and dryness which
assimilates the vegetation and physical aspect of the adjacent
islands to its own. A little further eastward in Timor and the Ke
Islands, a moister climate prevails; the southeast winds blowing
from the Pacific through Torres Straits and over the damp forests
of New Guinea, and as a consequence, every rocky islet is clothed
with verdure to its very summit. Further west again, as the same
dry winds blow over a wider and wider extent of ocean, they have
time to absorb fresh moisture, and we accordingly find the island
of Java possessing a less and less arid climate, until in the
extreme west near Batavia, rain occurs more or less all the year
round, and the mountains are everywhere clothed with forests of
unexampled luxuriance.
Contrasts in Depth of Sea. - It was first pointed out by Mr.
George Windsor Earl, in a paper read before the Royal
Geographical Society in 1845, and subsequently in a pamphlet "On
the Physical Geography of South-Eastern Asia and Australia",
dated 1855, that a shallow sea connected the great islands of
Sumatra, Java, and Borneo with the Asiatic continent, with which
their natural productions generally agreed; while a similar
shallow sea connected New Guinea and some of the adjacent islands
to Australia, all being characterised by the presence of
marsupials.
We have here a clue to the most radical contrast in the
Archipelago, and by following it out in detail I have arrived at
the conclusion that 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.
