e, the Sandwich
Islands, Tristan d'Acunha, and New Zealand, that we find any near
approach to that remarkable preponderance of ferns which is
characteristic of the Carboniferous flora. It has been observed that
tree ferns and other forms of vegetation which flourished most
luxuriantly within the tropics, extend to a much greater distance from
the equator in the southern hemisphere than in the northern, being found
even as far as 46 degrees S. latitude in New Zealand. There is little
doubt that this is owing to the more uniform and moist climate
occasioned by the greater proportional area of sea. Next to ferns and
pines, the most abundant vegetable forms in the coal formation are the
Calamites, Lepidodendra, Sigillariae, and Stigmariae. These were
formerly considered to be so closely allied to tropical genera, and to
be so much greater in size than the corresponding tribes now inhabiting
equatorial latitudes, that they were thought to imply an extremely hot,
as well as humid and equable climate. But recent discoveries respecting
the structure and relations of these fossil plants, have shown that they
deviated so widely from all existing types in the vegetable world, that
we have more reason to infer from this evidence a widely different
climate in the Carboniferous era, as compared to that now prevailing,
than a temperature extremely elevated.[156] Palms, if not entirely
wanting when the strata of the carboniferous group were deposited,
appear to have been exceedingly rare.[157] The Coniferae, on the other
hand, so abundantly met with in the coal, resemble Araucariae in
structure, a family of the fir tribe, characteristic at present of the
milder regions of the southern hemisphere, such as Chili, Brazil, New
Holland, and Norfolk Island.

"In regard to the geographical extent of the ancient vegetation, it was
not confined," says M. Brongniart, "to a small space, as to Europe, for
example; for the same forms are met with again at great distances. Thus,
the coal-plants of North America are, for the most part, identical with
those of Europe, and all belong to the same genera. Some specimens,
also, from Greenland, are referable to ferns, analogous to those of our
European coal-mines."[158] The fossil plants brought from Melville
Island, although in a very imperfect state, have been supposed to
warrant similar conclusions;[159] and assuming that they agree with
those of Baffin's Bay, mentioned by M. Brongniart, how shall we ex