320 Ancient Vegetation of the Earth. 
have almost a complete resemblance, in all the points of their 
organization, with the Equiseta (Horsetails) which grow so abun- 
dantly in the marshy situations of our climates, and of which the 
stems, hardly as large as the finger, rarely surpass one metre (about 
394 inches) in height. The Calamites, then, were arborescent 
Equiseta, a form under which these plants have wholly disap- 
peared from the surface of the earth. 
‘The Lepidodendrons, of which the numerous species appear to 
have mainly constituted the forests of this ancient epoch, and 
which have probably contributed more than all other vegetables 
to the formation of coal, differ very little from our Lycopodiz. 
We recognize in their trunks essentially the same structure, the 
same mode of ramification ; and in short we see inserted upon their 
branches leaves and fruits analogous to those of these vegetables. 
But, while the Lycopodiz of the present day are small plants, 
most frequently creeping, and similar to the great mosses, attain- 
ing very rarely one metre (about 394 inches) in height, and cov- 
ered with very diminutive leaves, the Lepidodendrons, preserving 
the same form and aspect, elevated themselves to twenty oF 
twenty-five métres (a little more than 65 to 82 feet,) having, at 
their base, near one métre (about 394 inches) of diameter, with 
leaves which sometimes attained to half a métre (over 194 inches) 
in length. These were, consequently, arborescent Lycopodie, 
comparable, by their stature, to the largest Firs, of which they 
enjoyed the rank, in this primitive world ; forming, as these noW 
do, immense forests, in the shade of which were developed the 
F'erns, so numerous at that period. . 
How different this powerful vegetation from that which now 
clothes, in ever-varying tints, the surface of the earth! Magni- 
tude, strength, and activity of growth, constituted its essential 
characteristicks ; the smallest plants of our epoch were then rep- 
resented by gigantick forms; and yet, what simplicity of orgaul- 
zation, and what uniformity in the midst of a vegetation so eno!- 
mous! 
At the present day, even in those regions where nature has 
suffered no change at the hand of man, the eye reposes with de- 
light upon trees which are immediately distinguishable by the 
diversity of their form, and the tints of their foliage ; and whieh 
often support flowers or fruits of the most dissimilar colours. ‘This 
Variety of aspect is still more strongly illustrated by a contem- 
