hanges. Short as the Era is, compared
with its predecessors, it is even more eventful and stimulating than
they, and closes with what Professor Chamberlin calls "the greatest
deformative movements in post-Cambrian history." In the main it has,
from the evolutionary point of view, the same significant character
as the two preceding eras. Its middle portion is an age of expansion,
indulgence, exuberance, in which myriads of varied forms are thrown upon
the scene, its later part is an age of contraction, of annihilation,
of drastic test, in which the more effectively organised will be chosen
from the myriads of types. Once more nature has engendered a vast brood,
and is about to select some of her offspring to people the modern world.
Among the types selected will be Man.

CHAPTER XVI. THE FLOWER AND THE INSECT

AS we approach the last part of the geological record we must neglect
the lower types of life, which have hitherto occupied so much of
our attention, so that we may inquire more fully into the origin and
fortunes of the higher forms which now fill the stage. It may be noted,
in general terms, that they shared the opulence of the mid-Tertiary
period, produced some gigantic specimens of their respective families,
and evolved into the genera, and often the species, which we find living
to-day. A few illustrations will suffice to give some idea of the later
development of the lower invertebrates and vertebrates.

Monstrous oysters bear witness to the prosperity of that ancient and
interesting family of the Molluscs. In some species the shells were
commonly ten inches long; the double shell of one of these Tertiary
bivalves has been found which measured thirteen inches in length, eight
in width, and six in thickness. In the higher branch of the Mollusc
world the naked Cephalopods (cuttle-fish, etc.) predominate over the
nautiloids--the shrunken survivors of the great coiled-shell race. Among
the sharks, the modern Squalodonts entirely displace the older types,
and grow to an enormous size. Some of the teeth we find in Tertiary
deposits are more than six inches long and six inches broad at the base.
This is three times the size of the teeth of the largest living shark,
and it is therefore believed that the extinct possessor of these
formidable teeth (Carcharodon megalodon) must have been much more than
fifty, and was possibly a hundred, feet in length. He flourished in
the waters of both Europe and America during t