ders, related to fishes in having gills when young) commenced, and land-plants were first in exuberant growth, the Carboniferous age (the
land-plants, as stated, cleansing the atmosphere from carbonic acid for
land animals). Then followed an Age in which true reptiles increased
in numbers and diversity, by multiplied creations, until there were
reptiles larger than whales in the water, immense leviathan reptiles
on the land, and flying reptiles in the air, so that each of the
elements was taken possession of by these scaly tribes. This was the Reptilian age. In
its progress, reptiles passed their climax, and before its close,
commenced their decline ; the race, since then, has been a
comparatively feeble one.
Moreover,
in each of these Ages, there were many distinct creations succeeding to
exterminations of previously existing life. Through the Silurian,
Devonian, Carboniferous and Reptilian Ages in America, the fifth day of
Genesis, fifteen times at least the seas were swept of their
species, so that, in the rocky folios of the succeeding epoch, not a
species of the former epoch occurs, or only half a dozen or so out of
hundreds. After each, life was again reinstated by the Creative Hand,
life in all the departments that had thus far been introduced to the
globe, new mollusca, new corals, new cri-noids, new trilobites; and if
the Age of Fishes were in progress, new fishes also, and so on; making
a complete creation for the time. Even in the Age of Fishes alone (the
Devonian age), there were four such revolutions in America,
with new creations throughout. Moreover, there were many partial
destructions and restorations at other times. These exterminations can
be proved, in many cases, to have been produced, either by the escape
of heat, through fissures, from the earth's interior, or the elevation
of the sea-bottom to dry land, or some convulsion in the earth's crust.
They were, in general, connected with the earth's physical history.
Recapitulating
the geological Ages mentioned, and adding those following, they are
(naming them, as has been done by Agassiz, from the dominant type) :
I. the Age of Molluscsj^^the Silurian; II. the Age of Fishes, or the Devonian flK the Age of Coal-plants and
