igher organization to find roothold; and as the archipelago
and its constituent islands grew larger, and had more multiplied
relations with winds and waters, such higher plants might be expected
ultimately to have their seeds transferred from the nearest lands. After
something like a Flora had thus colonized the surface, it would become
possible for insects to exist; and of air-breathing creatures, insects
would manifestly be among the first to find their way from elsewhere.
As, however, terrestrial organisms, both vegetal and animal, are less
likely than marine organisms to survive the accidents of transport from
distant shores; it is inferable that long after the sea surrounding
these new lands had acquired a varied Flora and Fauna, the lands
themselves would still be comparatively bare; and thus that the early
strata, like our Silurians, would afford no traces of terrestrial life.
By the time that large areas had been raised above the ocean, we may
fairly suppose a luxuriant vegetation to have been acquired. Under what
circumstances are we likely to find this vegetation fossilized? Large
surfaces of land imply large rivers with their accompanying deltas; and
are liable to have lakes and swamps. These, as we know from extant
cases, are favourable to rank vegetation; and afford the conditions
needful for preserving it in coal-beds. Observe, then, that while in the
early history of such a continent a carboniferous period could not
occur, the occurrence of a carboniferous period would become probable
after long-continued upheavals had uncovered large areas. As in our own
sedimentary series, coal-beds would make their appearance only after
there had been enormous accumulations of earlier strata charged with
marine fossils.

Let us ask next, in what order the higher forms of animal life would
make their appearance. We have seen how, in the succession of marine
forms, there would be something like a progress from the lower to the
higher: bringing us in the end to predaceous molluscs, crustaceans, and
fish. What are likely to succeed fish? After marine creatures, those
which would have the greatest chance of surviving the voyage would be
amphibious reptiles; both because they are more tenacious of life than
higher animals, and because they would be less completely out of their
element. Such reptiles as can live in both fresh and salt water, like
alligators; and such as are drifted out of the mouths of great rivers on
floatin