The strait is here fifteen miles wide, so that we may pass
in two hours from one great division of the earth to
another, differing as essentially in their animal life as
Europe does from America. If we travel from Java or
Borneo to Celebes or the Moluccas, the difference is still
more striking. In the first, the forests abound in monkeys
of many kinds, wild cats, deer, civets, and otters, and
numerous varieties of squirrels are constantly met with.
In the latter none of these occur; but the prehensiletailed
Cuscus is almost the only terrestrial mammal seen,
except wild pigs, which are found in all the islands, and
deer (which have probably been recently introduced) in
Celebes and the Moluccas. The birds which are most
abundant in the Western Islands are woodpeckers, barbets,
trogons, fruit-thrushes, and leaf-thrushes: they are seen
daily, and form the great ornithological features of the
country. In the Eastern Islands these are absolutely
unknown, honeysuckers and small lories being the most
common birds; so that the naturalist feels himself in a
new world, and can hardly realize that he has passed from
the one region to the other in a few days, without ever
being out of sight of land.
The inference that we must draw from these facts is
undoubtedly, that the whole of the islands eastwards
beyond Java and Borneo do essentially form a part of
a former Australian or Pacific continent, although some
tl PHYSICAL GEOGRAPHY. 23 CHAP. H
of them may never have been actually joined to it. This
continent must have been broken up not only before the
Western Islands were separated from Asia, but probably
before the extreme south-eastern portion of Asia was
raised above the waters of the ocean; for a great part of
the land of Borneo and Java is known to be geologically
of quite recent formation, while the very great difference
of species, and in many cases of genera also, between the
productions of the Eastern Malay Islands and Australia,
as well as the great depth of the sea now separating them,
all point to a comparatively long period of isolation.
It is interesting to observe among the islands themselves,
how a shallow sea always intimates a recent land-
connexion. The Aru Islands, Mysol, and Waigiou, as
well as Jobie, agree with New Guinea in their species of
mammalia and birds much more closely than they do with
the Moluccas, and we find that they are all united to New
Guinea by a shallow sea. In fact, the 100-fathom line
round New Guinea marks out accurately the range of the
true Paradise birds.
It is further to be noted—and this is a very interesting
point in connexion with theories of the dependence of
special forms of life on external conditions—that this
division of the Archipelago into two regions characterised
by a striking diversity in their natural productions, does
not in any way correspond to the main physical or