the lines I have indicated shows that
out of one hundred and fifty mammiferous and oviparous quadrupeds,
ninety are unknown to present naturalists, and that in the older layers
such oviparous quadrupeds as the ichthyosauri and plesiosauri abound.
The fossil elephant, the rhinoceros, the hippopotamus, and the mastodons
are not found in the more ancient layers. In fact, the species which
appear the same as ours are found only in superficial deposits.

Now, it cannot be held that the present races of animals differ from
the ancient races merely by modifications produced by local
circumstances and change of climate--for if species gradually changed,
we must find traces of these gradual modifications, and between the
palaeotheria and the present species we should have discovered some
intermediate formation; but to the present time none of these have
appeared.

Why have not the bowels of the earth preserved the monuments of so
remarkable a genealogy unless it be that the species of former ages were
as constant as our own, or at least because the catastrophe that
destroyed them had not left them time to give evidence of the changes?

Further, an examination of animals shows that though their superficial
characteristics, such as colour and size, are changeable, yet their more
radical characteristics do not change. Even the artificial breeding of
domestic animals can produce only a limited degree of variation. The
maximum variation known at the present time in the animal kingdom is
seen in dogs, but in all the varieties the relations of the bones remain
the same and the shape of the teeth undergoes no palpable change.

I know that some naturalists rely much on the thousands of ages which
they can accumulate with a stroke of the pen; but there is nothing which
proves that time will effect any more than climate and a state of
domestication. I have endeavoured to collect the most ancient documents
of the forms of animals. I have examined the engravings of animals
including birds on the numerous columns brought from Egypt to Rome. M.
Saint Hilaire collected all the mummies of animals he could obtain in
Egypt--cats, ibises, birds of prey, dogs, monkeys, crocodiles, etc.--and
we cannot find any more difference between them and those of the present
day than between human mummies of that date and skeletons of the present
day.

There is nothing, then, in known facts which can support the opinion
that the new genera discovered among