or water, or
through the medium of birds; and there is no reason to doubt that besides
the species that have actually established themselves, many others must
have reached the islands, but were either not suited to the climate and
other physical conditions, or did not find the insects necessary to their
fertilisation, and were therefore unable to maintain themselves.

If now we consider the extreme remoteness and isolation of these islands,
their small area and comparatively recent origin, and that, notwithstanding
all these disadvantages, they have acquired a very considerable and varied
flora and fauna, we shall, I think, be convinced, that with a larger area
and greater antiquity, mere separation from a continent by many hundred
miles of sea would not prevent a country from acquiring a very luxuriant
and varied flora, and a fauna also rich and peculiar as regards all classes
except terrestrial mammals, amphibia, and some groups of reptiles. This
conclusion will be of great importance in those cases where the evidence as
to the exact origin of the fauna and flora of an island is less clear and
satisfactory than in the case of the Azores and Bermuda.

* * * * *

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CHAPTER XIII

THE GALAPAGOS ISLANDS

Position and Physical Features--Absence of Indigenous Mammalia and
Amphibia--Reptiles--Birds--Insects and Land-Shells--The Keeling Islands
as Illustrating the Manner in which Oceanic Islands are Peopled--Flora
of the Galapagos--Origin of the Flora of the Galapagos--Concluding
Remarks.

The Galapagos differ in many important respects from the islands we have
examined in our last chapter, and the differences are such as to have
affected the whole character of their animal inhabitants. Like the Azores,
they are volcanic, but they are much more extensive, the islands being both
larger and more numerous; while volcanic action has been so recent that a
large portion of their surface consists of barren lava-fields. They are
considerably less distant from a continent than either the Azores or
Bermuda, being about 600 miles from the west coast of South America and a
little more than 700 from Veragua, with the small Cocos Islands
intervening; and they are situated on the equator instead of being in the
north temperate zone. They stand upon a deeply submerged bank, the 1,000
fathom line encircling all the more important islands at a few miles
distance, whence there ap