So that with respect to its plants no
less than with respect to its animals, we find that the island of St.
Helena constitutes a little world of unique species, allied among
themselves, but diverging so much from all other known forms that in
many cases they constitute unique genera.

_Sandwich Islands._--These are an extensive group of islands, larger
than any we have hitherto considered--the largest of the group being
about the size of Devonshire. The entire archipelago is volcanic, with
mountains rising to a height of nearly 14,000 feet. The group is
situated in the middle of the North Pacific, at a distance of
considerably over 2,000 miles from any other land, and surrounded by
enormous ocean depths. The only terrestrial vertebrata are two lizards,
one of which constitutes a peculiar genus. There are 24 aquatic birds,
five of which are peculiar; four birds of prey, two of which are
peculiar; and 16 land-birds, all of which are peculiar. Moreover, these
16 land-birds constitute no less than 10 peculiar genera, and even one
peculiar family of five genera. This is an amount of peculiarity far
exceeding that of any other islands, and, of course, corresponds with
the great isolation of this archipelago. The only other animals which
have here been carefully studied are the land-shells, and these tell the
same story as the birds. For there are no less than 400 species which
are all, without any exception, peculiar; while about three-quarters of
them go to constitute peculiar genera. Again, of the plants, 620 species
are believed to be endemic; and of these 377 are peculiar, yielding no
less than 39 peculiar genera.

* * * * *

Prejudice apart, I think we must all now agree that it is needless to
continue further this line of proof. I have chosen the smallest and most
isolated islands for the purposes of our present argument, first because
these furnish the most crucial kind of test, and next because they best
admit of being dealt with in a short space. But, if necessary, a vast
amount of additional material could be furnished, not only from other
small oceanic islands, but still more from the largest islands of the
world, such as Australia and New Zealand. However, after the detailed
inventories which have now been given in the case of some of the smaller
islands most remote from mainlands, we may well be prepared to accept it
as a general law, that _wherever_ there is evidence of land-area