ies of rushes, to
lycopodes.

As we ascend into the upper strata, vegetation becomes more and more
complex. Finally, near the surface, it resembles the vegetation actually
existing on the earth, with this characteristic circumstance, however,
which is well deserving attention, that certain vegetables which grow
only in southern climates, that the large palm-trees, for example, are
found in their fossil state in all latitudes, and even in the centre of
the frozen regions of Siberia.

In the primitive world, these northern regions enjoyed then, in winter,
a temperature at least equal to that which is experienced in the present
day under the parallels where the great palms commence to appear: at
Tobolsk, the inhabitants enjoyed the climate of Alicante or Algiers!

We shall deduce new proofs of this mysterious result from an attentive
examination of the size of plants.

There exist, in the present day, willow grass or marshy rushes, ferns,
and lycopodes, in Europe as well as in the tropical regions; but they
are not met with in large dimensions, except in warm countries. Thus, to
compare together the dimensions of the same plants is, in reality, to
compare, in respect to temperature, the regions where they are produced.
Well, place beside the fossil plants of our coal mines, I will not say
the analogous plants of Europe, but those which grow in the countries of
South America, and which are most celebrated for the richness of their
vegetation, and you will find the former to be of incomparably greater
dimensions than the latter.

The _fossil flora_ of France, England, Germany, and Scandinavia offer,
for example, ferns ninety feet high, the stalks being six feet in
diameter, or eighteen feet in circumference.

The _lycopodes_ which, in the present day, whether in cold or temperate
climates, are creeping-plants rising hardly to the height of a decimetre
above the soil; which even at the equator, under the most favourable
circumstances, do not attain a height of more than _one_ metre, had in
Europe, in the primitive world, an altitude of twenty-five metres.

One must be blind to all reason not to find, in these enormous
dimensions, a new proof of the high temperature enjoyed by our country
before the last irruptions of the ocean!

The study of _fossil animals_ is no less fertile in results. I should
digress from my subject if I were to examine here how the organization
of animals is developed upon the earth; what modif