t a distance of about 280 miles; moreover, icebergs formerly
brought boulders to its western shores, and they may have formerly
transported foxes, as now frequently happens in the arctic regions. Yet
it cannot be said that small islands will not support at least small
mammals, for they occur in many parts of the world on very small
islands, when lying 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 known that new species of mammals
appear and disappear at a quicker rate than other and lower animals.
Although 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 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 in their new homes in relation to
their new position, and we can understand the presence of endemic bats
on oceanic islands, with the absence of all other terrestrial mammals.

Another interesting relation exists, namely, between the depth of the
sea separating islands from each other, or from the nearest continent,
and the degree of affinity of their mammalian inhabitants. Mr. Windsor
Earl has made some striking observations on this head, since greatly
extended by Mr. Wallace's admirabl