wide. At the same time we may suppose islands to he
upheaved in mid-channel; and, as the subterranean forces
varied in intensity, and shifted their points of greatest
action, these islands would sometimes become connected
with the land on one side or other of the strait, and at
other times again be separated from it. Several islands
would at one time be joined together, at anothef would be
broken up again, till at last, after many long ages of such
intermittent action, we might have an irregular archipelago
of islands filling up the ocean channel of the Atlantic, in
whose appearance and arrangement we could discover
nothing to tell us which had been connected with Africa
and which with America. The animals and plants inhabiting
these islands would, however, certainly reveal
this portion of their former history. On those islands
which had ever formed a part of the South American
continent we should be sure to find such common birds
as chatterers and toucans and humming-birds, and some
of the peculiar American quadrupeds ; while on those
which had been separated from Africa, hornbills, orioles,
and honeysuckers would as certainly be found. Some
portion of the upraised land might at different times have
had a temporary connexion with both continents, and
would then contain a certain amount of mixture in its
living inhabitants. Such seems to have been the case
with the islands of Celebes and the Philippines. Other
islands, again, though in such close proximity as Bali and
Lombock, might each exhibit an almost unmixed sample
of the productions of the continents of which they had
directly or indirectly once formed a part.
In the Malay Archipelago we have, I believe, a case
exactly parallel to that which I have here supposed. We
have indications of a vast continent, with a peculiar fauna
and flora, having been gradually and irregularly broken
up; the island of Celebes probably marking its furthest
westward extension, beyond which was a wide ocean. At
the same time Asia appears to have been extending its
limits in a south-east direction, first in an unbroken mass,
then separated into islands as we now see it, and almost
coming into actual contact with the scattered fragments of
the great southern land.
From this outline of the subject, it will be evident how
important an adjunct Natural History is to Geology ; not
only in interpreting the fragments of extinct animals
found in the earth’s crust, but in determining past changes
in the surface which have left no geological record. It is
certainly a wonderful and unexpected fact, that an accurate
knowledge of the distribution of birds and insects should
enable us to map out lands and continents which disappeared
beneath the ocean long before the earliest traditions
of the human race. Wherever the geologist can
explore the earth’s surface, he can read much of its past