part of the Philippines in their volcanic structure, their
extreme fertility, their luxuriant forests, and their frequent
earthquakes; and Bali with the east end of Java has a climate almost
as dry and a soil almost as arid as that of Timor. Yet between these
corresponding groups of islands, constructed as it were after the same
pattern, subjected to the same climate, and bathed by the same oceans,
there exists the greatest possible contrast when we compare their animal
productions. Nowhere does the ancient doctrine--that differences
or similarities in the various forms of life that inhabit different
countries are due to corresponding physical differences or similarities
in the countries themselves--meet with so direct and palpable a
contradiction. Borneo and New Guinea, as alike physically as two
distinct countries can be, are zoologically wide as the poles asunder;
while Australia, with its dry winds, its open plains, its stony deserts,
and its temperate climate, yet produces birds and quadrupeds which are
closely related to those inhabiting the hot damp luxuriant forests,
which everywhere clothe the plains and mountains of New Guinea.

In order to illustrate more clearly the means by which I suppose this
great contrast has been brought about, let us consider what would occur
if two strongly contrasted divisions of the earth were, by natural
means, brought into proximity. No two parts of the world differ so
radically in their productions as Asia and Australia, but the difference
between Africa and South America is also very great, and these two
regions will well serve to illustrate the question we are considering.
On the one side we have baboons, lions, elephants, buffaloes, and
giraffes; on the other spider-monkeys, pumas, tapirs, anteaters,
and sloths; while among birds, the hornbills, turacos, orioles, and
honeysuckers of Africa contrast strongly with the toucans, macaws,
chatterers, and hummingbirds of America.

Now let us endeavour to imagine (what it is very probable may occur in
future ages) that a slow upheaval of the bed of the Atlantic should take
place, while at the same time earthquake-shocks and volcanic action on
the land should cause increased volumes of sediment to be poured down
by the rivers, so that the two continents should gradually spread out by
the addition of newly-formed lands, and thus reduce the Atlantic which
now separates them, to an arm of the sea a few hundred miles wide. At
the same ti