iting an island situated
above 300 miles from a continent or great continental island; and
many islands situated at a much less distance are equally barren. The
Falkland Islands, which are inhabited by a wolf-like fox, come nearest
to an exception; but this group cannot be considered as oceanic, as it
lies on a bank connected with the mainland; moreover, icebergs formerly
brought boulders to its western shores, and they may have formerly
transported foxes, as so frequently now happens in the arctic regions.
Yet it cannot be said that small islands will not support small mammals,
for they occur in many parts of the world on very small islands, if
close to a continent; and hardly an island can be named on which our
smaller quadrupeds have not become naturalised and greatly multiplied.
It cannot be said, on the ordinary view of creation, that there has
not been time for the creation of mammals; many volcanic islands are
sufficiently ancient, as shown by the stupendous degradation which they
have suffered and by their tertiary strata: there has also been time
for the production of endemic species belonging to other classes; and on
continents it is thought that mammals appear and disappear at a quicker
rate than other and lower animals. Though terrestrial mammals do not
occur on oceanic islands, aerial mammals do occur on almost every
island. New Zealand possesses two bats found nowhere else in the world:
Norfolk Island, the Viti Archipelago, the Bonin Islands, the Caroline
and Marianne Archipelagoes, and Mauritius, all possess their peculiar
bats. Why, it may be asked, has the supposed creative force produced
bats and no other mammals on remote islands? On my view this question
can easily be answered; for no terrestrial mammal can be transported
across a wide space of sea, but bats can fly across. Bats have been seen
wandering by day far over the Atlantic Ocean; and two North American
species either regularly or occasionally visit Bermuda, at the distance
of 600 miles from the mainland. I hear from Mr. Tomes, who has specially
studied this family, that many of the same species have enormous ranges,
and are found on continents and on far distant islands. Hence we have
only to suppose that such wandering species have been modified through
natural selection in their new homes in relation to their new position,
and we can understand the presence of endemic bats on islands, with the
absence of all terrestrial mammals.

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