neo, and mark the
furthest eastward range of the genus in the tropics; and two of Eastern
opossums (Cuscus), which are different from those of the Moluccas, and
mark the furthest westward extension of this genus and of the Marsupial
order. Thus we see that the Mammalia of Celebes are no less individual
and remarkable than the birds, since three of the largest and most
interesting species have no near allies in surrounding countries, but
seem vaguely to indicate a relation to the African continent.

Many groups of insects appear to be especially subject to local
influences, their forms and colours changing with each change of
conditions, or even with a change of locality where the conditions seem
almost identical. We should therefore anticipate that the individuality
manifested in the higher animals would be still more prominent in these
creatures with less stable organisms. On the other hand, however, we
have to consider that the dispersion and migration of insects is much
more easily effected than that of mammals or even of birds. They are
much more likely to be carried away by violent winds; their eggs may
be carried on leaves either by storms of wind or by floating trees, and
their larvae and pupae, often buried in trunks of trees or enclosed in
waterproof cocoons, may be floated for days or weeks uninjured over
the ocean. These facilities of distribution tend to assimilate the
productions of adjacent lands in two ways: first, by direct mutual
interchange of species; and secondly, by repeated immigrations of
fresh individuals of a species common to other islands, which by
intercrossing, tend to obliterate the changes of form and colour, which
differences of conditions might otherwise produce. Bearing these facts
in mind, we shall find that the individuality of the insects of Celebes
is even greater than we have any reason to expect.

For the purpose of insuring accuracy in comparisons with other islands,
I shall confine myself to those groups which are best known, or which
I have myself carefully studied. Beginning with the Papilionidae or
Swallow-tailed butterflies, Celebes possesses 24 species, of which the
large number of 18 are not found in any other island. If we compare this
with Borneo, which out of 29 species has only two not found elsewhere,
the difference is as striking as anything can be. In the family of the
Pieridae, or white butterflies, the difference is not quite so great,
owing perhaps to the more w