isms of various kinds may occasionally have of overcoming them, I
will now give a few detailed illustrations of the argument from
geographical distribution, as previously presented in its general form.

To begin with aquatic animals. As Darwin remarks, "the marine
inhabitants of the Eastern and Western shores of South America are very
distinct; with extremely few shells, crustacea, or echinodermata in
common." Again, westward of the shores of America, a wide space of open
ocean extends, which, as we have seen, furnishes as effectual a barrier
as does the land to any emigration of shallow-water animals. Now, as
soon as this reach of deep water is passed, we meet in the eastern
islands of the Pacific with another and totally distinct fauna. "So that
three marine faunas range northward and southward in parallel lines not
far from each other, under corresponding climates": they are, however,
"separated from each other by impassable barriers, either of land or
open sea": and it is in exact coincidence with the course of these
barriers that we find so remarkable a differentiation of the faunas[21].
Obviously, therefore, it is impossible to suggest that this correlation
is accidental. Altogether many thousands of species are involved, and
within this comparatively limited area they are sharply marked off into
three groups as to their natural affinities, and into three groups as to
their several basins. Hence, if all these species were separately
created, there is no escape from the conclusion that for some reason or
another the act of creation was governed by the presence of these
barriers, so that species deposited on the Eastern shores of South
America were formed with one set of natural affinities, while species
deposited on the Western shore were formed with another set; and
similarly with regard to the third set of species in the third basin,
which, extending over a whole hemisphere to the coast of Africa without
any further barrier, nowhere presents, over this vast area, any other
case of a distinct marine fauna. But what conceivable reason can there
have been thus to consult these geographical barriers in the original
creation of specific types? Even if such a case stood alone, it would
be strongly suggestive of error on the part of the special creation
theory. But let us take another case, this time from fresh-water faunas.

[21] The only exception is in the case of the fish on each side of
the isthmus of panam