vegetation, and it spread
over the swamps with great vigour. To say that the Coal-forests
were masses of Ferns, Horsetails, and Club-mosses is a lifeless and
misleading expression. The Club-mosses, or Lycopodiales, were massive
trees, rising sometimes to a height of 120 feet, and probably averaging
about fifty feet in height and one or two feet in diameter. The largest
and most abundant of them, the Sigillaria, sent up a scarred and fluted
trunk to a height of seventy or a hundred feet, without a branch,
and was crowned with a bunch of its long, tapering leaves. The
Lepidodendron, its fellow monarch of the forest, branched at the summit,
and terminated in clusters of its stiff, needle-like leaves, six' or
seven inches long, like enormous exaggerations of the little cones at
the ends of our Club-mosses to-day. The Horsetails, which linger
in their dwarfed descendants by our streams to-day, and at their
exceptional best (in a part of South America) form slender stems
about thirty feet high, were then forest-trees, four to six feet in
circumference and sometimes ninety feet in height. These Calamites
probably rose in dense thickets from the borders of the lakes, their
stumpy leaves spreading in whorls at every joint in their hollow
stems. Another extinct tree, the Cordaites, rivalled the Horsetails and
Club-mosses in height, and its showers of long and extraordinary leaves,
six feet long and six inches in width, pointed to the higher plant
world that was to come. Between these gaunt towering trunks the graceful
tree-ferns spread their canopies at heights of twenty, forty, and even
sixty feet from the ground, and at the base was a dense undergrowth
of ferns and fern-like seed-plants. Mosses may have carpeted the moist
ground, but nothing in the nature of grass or flowers had yet appeared.

Imagine this dense assemblage of dull, flowerless trees pervaded by a
hot, dank atmosphere, with no change of seasons, with no movement
but the flying of large and primitive insects among the trees and the
stirring of the ferns below by some passing giant salamander, with no
song of bird and no single streak of white or red or blue drawn across
the changeless sombre green, and you have some idea of the character of
the forests that are compressed into our seams of coal. Imagine these
forests spread from Spitzbergen to Australia and even, according to the
south polar expeditions, to the Antarctic, and from the United States to
Europe, to S