for the extinction of any particular
species or group of species.

ON THE FORMS OF LIFE CHANGING ALMOST SIMULTANEOUSLY THROUGHOUT THE
WORLD.

Scarcely any palaeontological discovery is more striking than the fact
that the forms of life change almost simultaneously throughout the
world. Thus our European Chalk formation can be recognised in many
distant regions, under the most different climates, where not a fragment
of the mineral chalk itself can be found; namely, in North America, in
equatorial South America, in Tierra del Fuego, at the Cape of Good Hope,
and in the peninsula of India. For at these distant points, the organic
remains in certain beds present an unmistakable resemblance to those
of the Chalk. It is not that the same species are met with; for in some
cases not one species is identically the same, but they belong to
the same families, genera, and sections of genera, and sometimes are
similarly characterised in such trifling points as mere superficial
sculpture. Moreover, other forms, which are not found in the Chalk of
Europe, but which occur in the formations either above or below, occur
in the same order at these distant points of the world. In the several
successive palaeozoic formations of Russia, Western Europe and North
America, a similar parallelism in the forms of life has been observed
by several authors; so it is, according to Lyell, with the European and
North American tertiary deposits. Even if the few fossil species which
are common to the Old and New Worlds were kept wholly out of view, the
general parallelism in the successive forms of life, in the palaeozoic
and tertiary stages, would still be manifest, and the several formations
could be easily correlated.

These observations, however, relate to the marine inhabitants of the
world: we have not sufficient data to judge whether the productions
of the land and of fresh water at distant points change 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
co-existed with sea-shells all still living; but as these anomalous
monsters co-existed with the Mastodon and Horse, it might at least
have been inferred that they had lived during one of the later tertiary
stages.

When the marine forms of life are spoken of as having