{ Compositæ, Leguminosæ, Umbel-
IV. Exogens Dicotyledonous Angiosperms { liferæ, Cruciferæ, Heaths.
{ All European except Conifers.
V. Endogens Monocotyledons { Palms, Lilies, Aloes, Rushes,
{ Grasses.
Calamites are among the most abundant fossil plants of the Carboniferous
period, and occur also in the Devonian. They are preserved as striated,
jointed, cylindrical, or compressed stems, with fluted channels or
furrows at their sides, and sometimes surrounded by a bituminous
coating, the remains of a cortical integument. They were originally
hollow, but the cavity is usually filled up with a substance into which
they themselves have been converted. They were divided into joints or
segments, and when broken across at their articulations they show a
number of striæ, originating in the furrows of the sides, and turning
inwards towards the centre of the stem. It is not known whether this
structure was connected with an imperfect diaphragm stretched across the
hollow of the stem at each joint, or merely represented the ends of
woody plates of which the solid part of the stem is composed. Their
extremities have been discovered to taper gradually to a point, as
represented in _C. cannæformis_ (Fig. 64), or to end abruptly, the
intervals becoming shorter and smaller. The obtuse point is now found to
be the root. Calamites are regarded as Equisetaceous plants; later
botanists consider that they belong to an extinct family of plants.
_Sigillariæ_ are the most abundant of all plants in the coal formation,
and were those principally concerned in the accumulation of the mineral
fuel of the Coal-measures. Not a mine is opened, nor a heap of shale
thrown out, but there occur fragments of its stem, marked externally
with small rounded impressions, and in the centre slight tubercles, with
a quincuncial arrangement. From the tubercles arise long ribbon-shaped
bodies, which have been traced in some instances to the length of twenty
feet.
[Illustration: Fig. 63.--Sphenophyllum restored.]
In the family of the Sigillarias we have already presented the bark of
_S. lævigata_, at page 138; on page 157 we give a drawing of the bark of
_S. reniformis_, one-third the natural size (Fig. 65).
In the family of the Asterophyllites, the leaf of _A. foliosa_ (Fig.
66); and the foliage of _Annularia orifolia_ (Fig. 67) are remarkable.
In addition to these, we present, in Fig. 63, a restoration of one of
these Asterophyllites, the _Sphenophyllum_, after M. Eugene
Deslongchamps. This herbaceous tree, like the Calamites, would present
the appearance of an immense asparagus, twenty-five to thirty feet high.
It is represented here with its branches and _fronds_, which bear some
resemblance to the leaves of the ginkgo. The bud, as represented in the
figure, is terminal, and not axillary, as in some of the Calamites.
[Illustration: Fig. 64.--Calamites cannæformis. One-third natural size.]
If, during the Coal-period, the vegetable kingdom had reached its
maximum, the animal kingdom, on the contrary, was poorly represented.
Some remains have been found, both in America and Germany, consisting of
portions of the skeleton and the impressions of the footsteps of a
Reptile, which has received the name of Archegosaurus. In Fig. 68 is
represented the head and neck of _Archegosaurus minor_, found in 1847 in
the coal-basin of Saarbruck between Strasbourg and Trèves. Among the
animals of this period we find a few Fishes, analogous to those of the
Devonian formation. These are the _Holoptychius_ and _Megalichthys_,
having jaw-bones armed with enormous teeth. Scales of _Pygopterus_
have been found in the Northumberland Coal-shale at Newsham Colliery,
and also in the Staffordshire Coal-shale. Some winged insects would
probably join this slender group of living beings. It may then be said
with truth that the immense forests and marshy plains, crowded with
trees, shrubs, and herbaceous plants, which formed on the innumerable
isles of the period a thick and tufted sward, were almost destitute of
animals.
[Illustration: XI.--Ideal view of a marshy forest of the Coal Period.]
[Illustration: Fig. 65.--Sigillaria reniformis.]
[Illustration: Fig. 66.--Asterophyllites foliosa.]
On the opposite page (PL. XI.) M. Riou has attempted, under the
directions of M. Deslongchamps, to reproduce the aspect of Nature during
the period. A marsh and forest of the Coal-period are here represented,
with a short and thick vegetation, a sort of grass composed of
herbaceous Fern and mare’s-tail. Several trees of forest-height raise
their heads above this lacustrine vegetation.
On the left are seen the naked trunk of a _Lepidodendron_ and a
_Sigillaria_, an arborescent Fern rising between the two trunks. At the
foot of these great trees an herbaceous Fern and a _Stigmaria_ appear,
whose long ramification of roots, provided with reproductive spores,
extend to the water. On the right is the naked trunk of another
_Sigillaria_, a tree whose foliage is altogether unknown, a
_Sphenophyllum_, and a _Conifer_. It is difficult to describe with
precision the species of this last family, the impressions of which are,
nevertheless, very abundant in the Coal-measures.
[Illustration: Fig. 67.--Annularia orifolia.]
[Illustration: Fig. 68.--Head and neck of Archegosaurus minor.]
In front of this group we see two trunks broken and overthrown. These
are a _Lepidodendron_ and _Sigillaria_, mingling with a heap of
vegetable débris in course of decomposition, from which a rich humus
will be formed, upon which new generations of plants will soon develop
themselves. Some herbaceous Ferns and buds of _Calamites_ rise out of
the waters of the marsh.
A few Fishes belonging to the period swim on the surface of the water,
and the aquatic reptile _Archegosaurus_ shows its long and pointed
head--the only part of the animal which has hitherto been discovered
(Fig. 68). A _Stigmaria_ extends its roots into the water, and the
pretty _Asterophyllites_, with its finely-cut stems, rises above it in
the foreground.
A forest, composed of _Lepidodendra_ and _Calamites_, forms the
background to the picture.