aeontology) furnishes weighty evidence of
man's descent; for the circumstantial evidence derived from this source
is written without the possibility of a mistake, with no chance of
error, on the stratified rocks. It is true that the geological record
must be incomplete, because it can only preserve remains found in
certain favorable localities, and under particular conditions; that this
valuable record must be destroyed by processes of denudation, and
obliterated by processes of metamorphosis, it cannot be doubted. "Beds
of rock of any thickness, crammed full of organic remains, may yet,"
says Huxley, "by the percolation of water through them, or the influence
of subterranean heat (if they descend far enough toward the centre of
the earth), lose all trace of these remains, and present the appearance
of beds of rock formed under conditions in which there was no trace of
living forms. Such metamorphic rocks occur in formations of all ages;
and we know with perfect certainty, when they do appear, that they have
contained organic remains, and that those remains have been absolutely
obliterated." If we look at the geological record, we find:

THE FIRST EPOCH.--_The Archilithic_, or Primordial Epoch, constitutes
the _Age of Skull-less Animals and Sea-weed Forests_, and is made up of
the Laurentian, Cambrian, and Silurian Period.

THE SECOND EPOCH.--_The Palaeolithic_, or Primary Epoch, constitutes the
_Age of Fishes and Fern Forests_, and is made up of the Devonian, Coal,
and Permian Period.

THE THIRD EPOCH.--_The Mesolithic_, or Secondary Epoch, constitutes the
_Age of Reptiles and Pine Forests, Coniferae_, and is made up of the
Triassic, Jurassic, and Chalk Period.

THE FOURTH EPOCH.--_The Caenolithic_, or Tertiary Epoch, constitutes the
_Age of Mammals and Leaf Forests_, and is made up of the Eocene,
Miocene, and Phocene Period.

THE FIFTH EPOCH.--The _Anthropolithic_, or Quaternary Epoch, constitutes
the _Age of Man and Cultivated Forests,_ and is made up of the Glacial
and Postglacial Period, and the Period of Culture.

During the archilithic epoch the inhabitants of our planet, as has been
already stated, consisted of skull-less animals, or aquatic forms. No
remains of terrestrial animals or plants, dated from this period, have
as yet been found.

The archilithic period was longer than the whole long period between the
close of the archilithic and the present time; for if the total
thickness of all sedimentary