x, a pheasant-like ground cuckoo formerly thought to be peculiar,
are said to have been discovered also in Sumatra.

The insects and land-shells of Borneo and of the surrounding countries are
too imperfectly known to enable us to arrive at any accurate results with
regard to their distribution. They agree, however, with the birds and
mammals in their general approximation to Malayan forms, but the number of
peculiar species is perhaps larger.

The proportion here shown of less than one-fourth peculiar species of
mammalia and fully one-fourth peculiar species of land-birds, teaches us
that the possession of the power of flight affects but little the
distribution of {381} land-animals, and gives us confidence in the results
we may arrive at in those cases where we have, from whatever cause, to
depend on a knowledge of the birds alone. And if we consider the wide range
of certain groups of powerful flight--as the birds of prey, the swallows
and swifts, the king-crows, and some others, we shall be forced to conclude
that the majority of forest-birds are restricted by even narrow watery
barriers, to an even greater extent than mammalia.

_The Affinities of the Bornean Fauna._--The animals of Borneo exhibit an
almost perfect identity in general character, and a close similarity in
species, with those of Sumatra and the Malay Peninsula. So great is this
resemblance that it is a question whether it might not be quite as great
were the whole united; for the extreme points of Borneo and Sumatra are
1,500 miles apart--as far as from Madrid to Constantinople, or from the
Missouri valley to California. In such an extent of country we always meet
with some local species, and representative forms, so that we hardly
require any great lapse of time as an element in the production of the
peculiarities we actually find. So far as the forms of life are concerned,
Borneo, as an island, may be no older than Great Britain; for the time that
has elapsed since the glacial epoch would be amply sufficient to produce
such a redistribution of the species, consequent on their mutual relations
being disturbed, as would bring the islands into their present zoological
condition. There are, however, other facts to be considered, which seem to
imply much greater and more complex revolutions than the recent separation
of Borneo from Sumatra and the Malay Peninsula, and that these changes must
have been spread over a considerable lapse of time. In order to