... We have ... never been able to find a case in which the
circle has been closed by a direct affinity. In most cases a
palpable analogy has been substituted, in others the affinity is
very obscure or altogether doubtful....
If we now consider the geographical distribution of animals and
plants upon the earth, we shall find all the facts beautifully in
accordance with, and readily explained by, the present hypothesis.
A country having species, genera, and whole families peculiar to
it will be the necessary result of its having been isolated for a
long period, sufficient for many series of species to have been
created on the type of pre-existing ones, which, as well as many
of the earlier-formed species, have become extinct, and made the
groups appear isolated....
Such phenomena as are exhibited by the Galapagos Islands, which
contain little groups of plants and animals peculiar to
themselves, but most nearly allied to those of South America, have
not hitherto received any, even a conjectural explanation.
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