s of north latitude; and there is no reason to presume that the
lands at the borders of which they originated ever penetrated so far or
in such masses into the colder and arctic regions, so as to generate a
cold climate. In the southern hemisphere, where the predominance of sea
over land is now the distinguishing geographical feature, we
nevertheless find a large part of the continent of Australia, as well as
New Zealand, placed between the 30th and 50th degrees of S. latitude.
The two islands of New Zealand taken together, are between 800 and 900
miles in length, with a breadth in some parts of ninety miles, and they
stretch as far south as the 46th degree of latitude. They afford,
therefore, a wide area for the growth of a terrestrial vegetation, and
the botany of this region is characterized by abundance of ferns, one
hundred and forty species of which are already known, some of them
attaining the size of trees. In this respect the southern shores of New
Zealand in the 46th degree of latitude almost vie with tropical islands.
Another point of resemblance between the Flora of New Zealand and that
of the ancient carboniferous period is the prevalence of the fir tribe
or of coniferous wood.

An argument of some weight in corroboration of the theory above
explained respecting the geographical condition of the temperate and
arctic latitudes of the northern hemisphere in the carboniferous period
may also be derived from ah examination of those groups of strata which
immediately preceded the coal. The fossils of the Devonian and Silurian
strata in Europe and North America have led to the conclusion, that they
were formed for the most part in deep seas, far from land. In those
older strata land plants are almost as rare as they are abundant or
universal in the coal measures. Those ancient deposits, therefore, may
be supposed to have belonged to an epoch when dry land had only just
begun to be upraised from the deep; a theory which would imply the
existence during the carboniferous epoch of islands, instead of an
extensive continent, in the area where the coal was formed.

Such a state of things prevailing in the north, from the pole to the
30th parallel of latitude, if not neutralized by circumstances of a
contrary tendency in corresponding regions south of the line, would give
rise to a general warmth and uniformity of climate throughout the globe.

_Changes in physical geography between the formation of the
carboniferous