Travel Reference
In-Depth Information
The naturalist will obtain a clearer idea of the variety and interest of the productions of
this country, by the statement, that its land birds belong to 108 genera, of which 29 are ex-
clusively characteristic of it; while 35 belong to that limited area which includes the Moluc-
cas and North Australia, and whose species of these genera have been entirely derived from
New Guinea. About one-half of the New Guinea genera are found also in Australia, about
one-third in India and the Indo-Malay islands.
A very curious fact, not hitherto sufficiently noticed, is the appearance of a pure Malay
element in the birds of New Guinea. We find two species of Eupetes, a curious Malayan
genus allied to the forked-tail water-chats; two of Alcippe, an Indian and Malay wren-like
form; an Arachnothera, quite resembling the spider-catching honeysuckers of Malacca; two
species of Gracula, the Mynahs of India; and a curious little black Prionochilus, a saw-billed
fruit-pecker, undoubtedly allied to the Malayan form, although perhaps a distinct genus.
Now not one of these birds, or anything allied to them, occurs in the Moluccas, or (with one
exception) in Celebes or Australia; and as they are most of them birds of short flight, it is
very difficult to conceive how or when they could have crossed the space of more than a
thousand miles, which now separates them from their nearest allies. Such facts point to
changes of land and sea on a large scale, and at a rate which, measured by the time required
for a change of species, must be termed rapid. By speculating on such changes, we may eas-
ily see how partial waves of immigration may have entered New Guinea, and how all trace
of their passage may have been obliterated by the subsequent disappearance of the interven-
ing land.
There is nothing that the study of geology teaches us that is more certain or more im-
pressive than the extreme instability of the earth's surface. Everywhere beneath our feet we
find proofs that what is land has been sea, and that where oceans now spread out has once
been land; and that this change from sea to land, and from land to sea, has taken place, not
once or twice only, but again and again, during countless ages of past time. Now the study
of the distribution of animal life upon the present surface of the earth, causes us to look
upon this constant interchange of land and sea—this making and unmaking of continents,
this elevation and disappearance of islands—as a potent reality, which has always and
everywhere been in progress, and has been the main agent in determining the manner in
which living things are now grouped and scattered over the earth's surface. And when we
continually come upon such little anomalies of distribution as that just now described, we
find the only rational explanation of them, in those repeated elevations and depressions
which have left their record in mysterious, but still intelligible characters on the face of or-
ganic nature.
