Their distribution has been more accurately
studied, and we possess a much more complete knowledge of such
groups as mammals and birds in most of the islands, than we do of
the plants. It is these two classes which will supply us with
most of our facts as to the geographical distribution of
organized beings in this region.
The number of Mammalia known to inhabit the Indo-Malay region is
very considerable, exceeding 170 species. With the exception of
the bats, none of these have any regular means of passing arms of
the sea many miles in extent, and a consideration of their
distribution must therefore greatly assist us in determining
whether these islands have ever been connected with each other or
with the continent since the epoch of existing species.
The Quadrumana or monkey tribe form one of the most
characteristic features of this region. Twenty-four distinct
species are known to inhabit it, and these are distributed with
tolerable uniformity over the islands, nine being found in Java,
ten in the Malay peninsula, eleven in Sumatra, and thirteen in
Borneo. The great man-like Orangutans are found only in Sumatra
and Borneo; the curious Siamang (next to them in size) in Sumatra
and Malacca; the long-nosed monkey only in Borneo; while every
island has representatives of the Gibbons or long-armed apes, and
of monkeys.
