Travel Reference
In-Depth Information
about twenty miles wide. Evidently there are now great facilities for the natural productions
of Java to spread over and occupy the whole of these islands, while those of Australia would
find very great difficulty in getting across. To account for the present state of things, we
should naturally suppose that Australia was once much more closely connected with Timor
than it is at present; and that this was the case is rendered highly probable by the fact of a
submarine bank extending along all the north and west coast of Australia, and at one place
approaching within twenty miles of the coast of Timor. This indicates a recent subsidence of
North Australia, which probably once extended as far as the edge of this bank, between
which and Timor there is an unfathomed depth of ocean.
I do not think that Timor was ever actually connected with Australia, because such a large
number of very abundant and characteristic groups of Australian birds are quite absent, and
not a single Australian mammal has entered Timor; which would certainly not have been the
case had the lands been actually united. Such groups as the bower birds (Ptilonorhynchus),
the black and red cockatoos (Calyptorhynchus), the blue wrens (Malurus), the crowshrikes
(Cracticus), the Australian shrikes (Falcunculus and Colluricincla), and many others, which
abound all over Australia, would certainly have spread into Timor if it had been united to
that country, or even if for any long time it had approached nearer to it than twenty miles.
Neither do any of the most characteristic groups of Australian insects occur in Timor; so
that everything combines to indicate that a strait of the sea has always separated it from
Australia, but that at one period this strait was reduced to a width of about twenty miles.
But at the time when this narrowing of the sea took place in one direction, there must
have been a greater separation at the other end of the chain, or we should find more equality
in the numbers of identical and representative species derived from each extremity. It is true
that the widening of the strait at the Australian end by subsidence, would, by putting a stop
to immigration and intercrossing of individuals from the mother country, have allowed full
scope to the causes which have led to the modification of the species; while the continued
stream of immigrants from Java, would, by continual intercrossing, check such modifica-
tion. This view will not, however, explain all the facts; for the character of the fauna of the
Timorese group is indicated as well by the forms which are absent from it as by those which
it contains, and is by this kind of evidence shown to be much more Australian than Indian.
No less than twenty-nine genera, all more or less abundant in Java, and most of which range
over a wide area, are altogether absent; while of the equally diffused Australian genera only
about fourteen are wanting. This would clearly indicate that there has been, till recently, a
wide separation from Java; and the fact that the islands of Bali and Lombock are small, and
are almost wholly volcanic, and contain a smaller number of modified forms than the other
