Two of these families have already been dealt with, viz., the ferns
(_felices_), and the equisetums, (_calamites_ and _equisetites_), and we
now have to pass on to another family. This is that which includes the
fossil representatives of the Lycopodiums, or Club-mosses, and which goes
to make up in some coals as much as two-thirds of the whole mass.
Everyone is more or less familiar with some of the living Lycopodiums,
those delicate little fern-like mosses which are to be found in many a
home. They are but lowly members of our British flora, and it may seem
somewhat astounding at first sight that their remote ancestors occupied
so important a position in the forests of the ancient period of which we
are speaking. Some two hundred living species are known, most of them
being confined to tropical climates. They are as a rule, low creeping
plants, although some few stand erect. There is room for astonishment
when we consider the fact that the fossil representatives of the family,
known as _Lepidodendra_, attained a height of no less than fifty feet,
and, there is good ground for believing, in many cases, a far greater
magnitude. They consist of long straight stems, or trunks which branch
considerably near the top. These stems are covered with scars or scales,
which have been caused by the separation of the petioles or leaf-stalks,
and this gives rise to the name which the genus bears. The scars are
arranged in a spiral manner the whole of the way up the stem, and the
stems often remain perfectly upright in the coal-mines, and reach into
the strata which have accumulated above the coal-seam.

[Illustration: FIG. 11.--Cast of _lepidodendron_ in sandstone.]

Count Sternberg remarked that we are unacquainted with any existing
species of plant, which like the _Lepidodendron_, preserves at all ages,
and throughout the whole extent of the trunk, the scars formed by the
attachment of the petioles, or leaf-stalks, or the markings of the leaves
themselves. The yucca, dracaena, and palm, entirely shed their scales
when they are dried up, and there only remain circles, or rings, arranged
round the trunk in different directions. The flabelliform palms preserve
their scales at the inferior extremity of the trunk only, but lose them
as they increase in age; and the stem is entirely bare, from the middle
to the superior extremity. In the ancient _Lepidodendron_, on the other
hand, the more ancient the scale of the leaf-stalk, the more