recently separated from i t ; for the adjacent district of
Palembang is new land, being a great alluvial swamp
formed by torrents from the mountains a hundred miles
distant. Banca, on the other hand, agrees with Malacca,
Singapore, and the intervening island of Lingen, in being
formed of granite and laterite; and these have all most
likely once formed an extension of the Malay peninsula.
As the rivers of Borneo and Sumatra have been for ages
filling up the intervening sea, we may be sure that its
depth has recently been greater, and it is very probable
that those large islands were never directly connected with
each other except through the Malay peninsula. At that
period the same species of squirrel and Pitta may have
inhabited all these countries ; but when the subterranean
disturbances occurred which led to the elevation of the
volcanoes of Sumatra, the small island of Banca may have
been separated first, and its productions being thus isolated
might be gradually modified before the separation of the
larger islands had been completed. As the southern part of
Sumatra extended eastward and formed the narrow straits
of Banca, many birds and insects and some Mammalia
would cross from one to the other, and thus produce a
general similarity of productions, while a few of the older
inhabitants remained, to reveal by their distinct forms their
different origin. Unless we suppose some such changes
in physical geography to have occurred, the presence of
peculiar species of birds and mammals in such an island
as Banca is a hopeless puzzle ; and I think I have shown
that the changes required are by no means so improbable
as a mere glance at the map would lead us to suppose.
Por our next example let us take the great islands of
Sumatra and Java. These approach so closely together,
and the chain of volcanoes that runs through them gives
such an air of unity to the two, that the idea of their
having been recently dissevered is immediately suggested.
The natives of Java, however,- go further than this; for
they actually have a tradition of the catastrophe which
broke them asunder, and fix its date at not much more
than a thousand years ago. It becomes interesting, therefore,
to see what support is given to this view by the
comparison of their animal productions.
The Mammalia have not been collected with sufficient
completeness in both islands to make a general comparison
of much value, and so many species have been obtained
only as live specimens in captivity, that their locality has
often been erroneously given,—the island in which they
were obtained being substituted for that from which they
originally came. Taking into consideration only those
whose distribution is more accurately known, we learn that
Sumatra is, in a zoological sense, more nearly related to
Borneo than it is to Java. The great man-like apes, the
elephant, the tapir, and the Malay bear, are all common to
Q 2