productions of the land and of fresh water change at distant points in
the same parallel manner. We may doubt whether they have thus changed:
if the Megatherium, Mylodon, Macrauchenia, and Toxodon had been brought
to Europe from La Plata, without any information in regard to their
geological position, no one would have suspected that they had coexisted
with still living sea-shells; but as these anomalous monsters coexisted
with the Mastodon and Horse, it might at least have been inferred that
they had lived during one of the latter tertiary stages.

When the marine forms of life are spoken of as having changed
simultaneously throughout the world, it must not be supposed that this
expression relates to the same thousandth or hundred-thousandth year, or
even that it has a very strict geological sense; for if all the marine
animals which live at the present day in Europe, and all those that
lived in Europe during the pleistocene period (an enormously remote
period as measured by years, including the whole glacial epoch), were to
be compared with those now living in South America or in Australia, the
most skilful naturalist would hardly be able to say whether the existing
or the pleistocene inhabitants of Europe resembled most closely those of
the southern hemisphere. So, again, several highly competent observers
believe that the existing productions of the United States are more
closely related to those which lived in Europe during certain later
tertiary stages, than to those which now live here; and if this be so,
it is evident that fossiliferous beds deposited at the present day on
the shores of North America would hereafter be liable to be classed with
somewhat older European beds. Nevertheless, looking to a remotely future
epoch, there can, I think, be little doubt that all the more modern
MARINE formations, namely, the upper pliocene, the pleistocene and
strictly modern beds, of Europe, North and South America, and Australia,
from containing fossil remains in some degree allied, and from not
including those forms which are only found in the older underlying
deposits, would be correctly ranked as simultaneous in a geological
sense.

The fact of the forms of life changing simultaneously, in the above
large sense, at distant parts of the world, has greatly struck those
admirable observers, MM. de Verneuil and d'Archiac. After referring
to the parallelism of the palaeozoic forms of life in various parts
of Europe, they a