d tree, when established on an island and
having to compete with herbaceous plants alone, might readily gain an
advantage by growing taller and taller and overtopping the other plants. If
so, natural selection would often tend to add to the stature of herbaceous
plants when growing on an oceanic island, to whatever order they belonged,
and thus convert them first into bushes and ultimately into trees.

With respect to the absence of whole orders on oceanic islands, Bory St.
Vincent long ago remarked that Batrachians (frogs, toads, newts) have never
been found on any of the many islands with which the great oceans are
studded. I have taken pains to verify this assertion, and I have found it
strictly true. I have, however, been assured that a frog exists on the
mountains of the great island of New Zealand; but I suspect that this
exception (if the information be correct) may be explained through glacial
agency. This general absence of frogs, toads, and newts on so many oceanic
islands cannot be accounted for by their physical conditions; indeed it
seems that islands are peculiarly well fitted for these animals; for frogs
have been introduced into Madeira, the Azores, and Mauritius, and have
multiplied so as to become a nuisance. But as these animals and their spawn
are known to be immediately killed by sea-water, on my view we can see that
there would be great difficulty in their transportal across the sea, and
therefore why they do not exist on any oceanic island. But why, on the
theory of creation, they should not have been created there, it would be
very difficult to explain.

Mammals offer another and similar case. I have carefully searched the
oldest voyages, but have not finished my search; as yet I have not found a
single {394} instance, free from doubt, of a terrestrial mammal (excluding
domesticated animals kept by the natives) inhabiting 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 th