on of separated
land had been anything like as large as Celebes now is, it would certainly
have preserved a far more abundant and varied fauna. To explain the facts
we have the choice of two theories:--either that the original island has
since its separation been greatly reduced by submersion, so as to lead to
the extinction of most of the higher land animals; or, that it originally
formed part of an independent land stretching eastward, and was only united
with the Asiatic continent for a short period, or perhaps even never united
at all, but so connected by intervening islands separated by narrow straits
that a few mammals might find their way across. The latter supposition
appears best to explain the facts. The three animals in question are such
as might readily pass over narrow straits from island to island; and we are
thus better enabled to understand the complete absence of the arboreal
monkeys, of the Insectivora, and of the very numerous and varied Carnivora
and Rodents of Borneo, all of which except the squirrels are entirely
unrepresented in Celebes by any peculiar and ancient forms.

The question at issue can only be finally determined by geological
investigations. If Celebes has once formed part of Asia, and participated
in its rich mammalian fauna, which has been since destroyed by submergence,
then some {458} remains of this fauna must certainly be preserved in caves
or late Tertiary deposits, and proofs of the submergence itself will be
found when sought for. If, on the other hand, the existing animals fairly
represent those which have ever reached the island, then no such remains
will be discovered, and there need be no evidence of any great and
extensive subsidence in late Tertiary times.

_Birds of Celebes._--Having thus clearly placed before us the problem
presented by the mammalian fauna of Celebes, we may proceed to see what
additional evidence is afforded by the birds and any other groups of which
we have sufficient information. About 164 species of true land-birds are
now known to inhabit the island of Celebes itself. Considerably more than
half of these (ninety-four species) are peculiar to it; twenty-nine are
found also in Borneo and the other Malay Islands, to which they specially
belong; while sixteen are common to the Moluccas or other islands of the
Australian region; the remainder being species of wide range and not
characteristic of either division of the Archipelago. We have here a large