imals nor plants existed, there
was an age in the physical history of the world when the lands consisted
of low islands,--when neither great depths nor lofty heights diversified
the surface of the earth,--when both the animal and vegetable creation,
however numerous, was inferior to the later ones, and comparatively
uniform in character,--when marine Cryptogams were the highest plants, and
Fishes were the highest animals. And this broad statement holds good for
the whole of that time, even though it was not without its minor changes,
its new forms of animal and vegetable life, its variations of level, its
upheavals and subsidences; for, nevertheless, through its whole duration,
it was the age of low detached lands,--it was the age of Cryptogams,--it
was the age of Fishes. From its beginning to its close, no higher type in
the animal kingdom, no loftier group in the vegetable world, made its
appearance.

There was an age in the physical history of the world when the patches of
land already raised above the water became so united as to form large
islands; and though the aspect of the earth retained its insular
character, yet the size of the islands, their tendency to coalesce by the
addition of constantly increasing deposits, and thus to spread into wider
expanses of dry land, marked the advance toward the formation of
continents. This extension of the dry land was brought about not only by
the gradual accumulation of materials, but also by the upheaval of large
tracts of stratified deposits; for, though the loftiest mountain-chains
did not yet exist, ranges like those of the Alleghanies and the Jura
belong to this division of the world's history. During this time, the
general character of the animal and vegetable kingdoms was higher than
during the previous age. Reptiles, many and various, gigantic in size,
curious in form, some of them recalling the structure of fishes, others
anticipating birdlike features, gave a new character to the animal world,
while in the vegetable world the reign of the aquatic Cryptogams was over,
and terrestrial Cryptogams, and, later, Gymnosperms and Monocotyledonous
trees, clothed the earth with foliage. Such was the character of this
second age from its opening to its close; and though there are
indications, that, before it was wholly past, some low, inferior Mammalian
types of the Marsupial kind were introduced,[2] and also a few
Dicotyledonous plants, yet they were not numerous or striking