mollusks, and the articulata, the. Lower forms have entirely disappeared
; and the tertiary species are frequently almost identical with
those now living: among vertebrata, the enamelled fishes of the earlier
epochs have been replaced by those with scales like the living
species; and, in a word, the whole tertiary fauna resembles oui
present.
Another importapt change is noticed in the relative distribution of
animals and plants. In the early history of the earth, the same animals
were spread widely over the face of the globe;. nearly the whole
earth was covered with water, and a uniform temperature everywhere
prevailed: none hut marine animals existed, and there was nothing
to prevent a great uniformity of type. In the tertiary ¡era everything
had altered the earth’s surface was varied with islands and con-
tine^ ’ mountains and valleys, with hills and plains; the sea,
gathered into separate basins, was divided by impassable barriers.
Here, accordingly, we find another great step towards the present
condition of organized nature on the earth’s surface: not only have
higher orders of animals appeared, hut they are confined within narrower
limits. The fossils of the tertiary system, in different regions,
are as distinct as the present faunae and florae of those, countries.
Each portion of the land, as it rose above the deep, became peopled with
animals and plants best adapted to its occupancy; and the waters
necessarily partaking of the physical change, the marine species which
swarmed along the shores underwent a corresponding modification.
The earth was now inhabited by the great mammifers, whose constitution
most nearly resembles that of mankind: where they existed,
assuredly, man could have existed also. They approximate to humanity
m their intelligence, their senses, their wants, their passions,, their animal
functions; and when they had “ multiplied exceedingly,” we may
suppose that man would not he long in making his appearance. Here
we meet for the first time with fossil monkeys; the type whose organization
most closely assimilates to the human. ,*It is only within a few
years that fossil monkeys have been discovered, and their supposed
absence was formerly cited as a proof of their recent origin. Monkeys,
in still prevalent systems of creation, are supposed to have been coeval
with, or at least hut little anterior to, man; the absence of their organic
remains being considered as satisfactory, evidence that both
men and monkeys were mere creations of yesterday! Fossil monkeys,
nevertheless, have been found in England, France,. India, and South
America. In India, several different species have turned up in tertiary
strata, on the Himalaya mountains. The French fossils, found
in fresh-water strata of the tertiary era, belong to the gibbon or tailless
ape, which stands next, in the scale of organization, to the orangs.
The American specimen, brought from Brazil by Dr. Lund, is referred
to an extinct genus and species peculiar to that country. And
the English fossils, belonging to the genus maeacus and an extinct
species, exhumed from the London clay, were associated with crocodiles,
turtles, nautili, besides many curious tropical fruits.*
Only a few fossil quadrumanes have as yet been discovered; but
a single one is sufficient to establish their existence. The number of
animals preserved in rocky strata may hear hut a small proportion to
those which have been utterly destroyed. Thus, in the Connecticut
sandstone, the tracks of more than forty species of birds and quadrupeds
have been found distinctly marked. Some of these birds must
have been at least twelve or fifteen feet high; and yet no other vestige
of their existence has been discovered. They were the colossal residents
of that valley for ages; they have all vanished; and h ad it not
been for the plastic nature of the yielding sand whereon they waded
along the river’s hanks, they would not have left even a footprint
behind them. May there not he other creatures which have left no
trace whatever of their existence ? t
In each of the great geological epochas, life was quite as abundant as
at the present day. Ah departments of the Animal Kingdom had their
representatives, and some of them were even more numerous then than
at present. Those immense tracts formed by zoophytes, and the incomprehensible
masses of microscopic shells, would almost seem to favor
the theory that the whole earth is formed of the debris of organized
beings. Fossil fishes are far more plentiful than their living representatives;
and more shells have been found in the single basin of
Paris than' now exist in the whole Mediterranean.J The remains of
the giant reptiles show their exuhe'rance; and now-extinct species of
mammals must have at least equalled in numbers, as they far exceed
in size, their living successors. Perhaps the most striking example
is seen in the inexhaustible multitude of fossil elephants daily discovered
in Siberia. Their tusks have been an object of traffic in ivory
for centuries; and in some places they have existed in such prodigious
quantities, that the ground is still tainted with the smell of animal
matter. Their huge skeletons are found from the frontiers of Europe
through all Northern Asia to its extreme eastern point, and from the
foot of the Altai Mountains to the shores of the Frozen Ocean — a
surface equal in extent to the whole of Europe. Some islands in the
Arctic Sea are chiefly composed of their remains, mixed-with the
hones of various other animals of living genera, hut of extinct
species. §
* Lyell: Principles. f Hitchcock: Geology.
$ Lieut. Anjou’s Polar Voyage.
J Agassiz.