ls both of
the same and of allied species have descended from a single parent; and
therefore have all proceeded from a common birthplace, notwithstanding that
in the course of time they have come to inhabit distant points of the
globe. I have already stated that I cannot honestly admit Forbes's view on
continental extensions, which, if legitimately followed out, would lead to
the belief that within the recent period all existing islands have been
nearly or quite joined to some continent. This view would remove many
difficulties, but it would not, I think, explain all the facts in regard to
insular productions. In the following remarks I shall not confine myself to
the mere question of dispersal; but shall consider some other facts, which
bear on the truth of the two theories of independent creation and of
descent with modification.

The species of all kinds which inhabit oceanic islands are few in number
compared with those on equal continental areas: Alph. de Candolle admits
this for plants, and Wollaston for insects. If we look to the large size
and varied stations of New Zealand, extending over 780 miles of latitude,
and compare its flowering plants, only 750 in number, with those on an
equal area at the Cape of Good Hope or in Australia, we must, I think,
admit that something quite independently of any difference in physical
conditions has caused so great a difference in number. Even the uniform
county of Cambridge has 847 plants, and the little island of Anglesea 764,
but a few ferns and a few introduced plants are included in these numbers,
and the comparison in some other respects is not quite fair. We have
evidence that the barren island of Ascension aboriginally possessed under
half-a-dozen flowering plants; {390} yet many have become naturalised on
it, as they have on New Zealand and on every other oceanic island which can
be named. In St. Helena there is reason to believe that the naturalised
plants and animals have nearly or quite exterminated many native
productions. He who admits the doctrine of the creation of each separate
species, will have to admit, that a sufficient number of the best adapted
plants and animals have not been created on oceanic islands; for man has
unintentionally stocked them from various sources far more fully and
perfectly than has nature.

Although in oceanic islands the number of kinds of inhabitants is scanty,
the proportion of endemic species (_i.e._ those found nowhere else in