makes the following observations: "I believe that there was a
considerably wide range of organisation in _cordaitinae_ as well as in
_calamites_ and _sigillariae_, and that it will eventually be found that
there were three lines of connection between the higher cryptogams
(flowerless) and the phaenogams (flowering), one leading from the
lycopodes by the _sigillariae_, another leading by the _cordaites_, and
the third leading from the _equisetums_ by the _calamites_. Still further
back the characters, afterwards separated in the club-mosses,
mare's-tails, and ferns, were united in the _rhizocarps_, or, as some
prefer to call them, the heterosporous _filicinae_."

In concluding this chapter dealing with the various kinds of plants which
have been discovered as contributing to the formation of
coal-measures, it would be as well to say a word or two concerning the
climate which must have been necessary to permit of the growth of such an
abundance of vegetation. It is at once admitted by all botanists that a
moist, humid, and warm atmosphere was necessary to account for the
existence of such an abundance of ferns. The gorgeous waving
tree-ferns which were doubtless an important feature of the landscape,
would have required a moist heat such as does not now exist in this
country, although not necessarily a tropical heat. The magnificent giant
lycopodiums cast into the shade all our living members of that class, the
largest of which perhaps are those that flourish in New Zealand. In New
Zealand, too, are found many species of ferns, both those which are
arborescent and those which are of more humble stature. Add to these the
numerous conifers which are there found, and we shall find that a forest
in that country may represent to a certain extent the appearance
presented by a forest of carboniferous vegetation. The ferns, lycopods,
and pines, however, which appear there, it is but fair to add, are mixed
with other types allied to more recent forms of vegetation.