But what tongue can describe the vegetable wonders of the forests where I grew? The woods were so thick, and the gloom so impenetrable in consequence, that it required a keen eye to make out individual peculiarities. Fancy Lepidodendra four or five feet in diameter, and as much as fifty or sixty feet high, and yet nothing but gigantic "clubmosses!" Their long leafy ribbons waved like the leaves of the aspen, and, where these had fallen off, the bark was most

gracefully and geometrically patterned

from their attachment. Thirty or forty different sorts of these immense club-mosses existed at the same time, each characterized

by different leaves

Fig. 42.

and bark. The gigan- Microscopical section of Fossil Wood, from tic Sigillariæ were

nearly related to them, the main difference being their longer leaves, straighter stems, and the larger marks made on the bark. The roots, also, of this latter class of trees were very peculiar, and stretched through the mud on every side, seeking a firm foundation for the tree to which they belonged. Shooting many feet above these great club-mosses were huge 'horse-tails," as easily distinguished from the rest as

the aspen-poplar nowadays is from oak and elm. These are called Calamites, and truly they were extraordinary objects. You have only to magnify the little

Fig. 43.

b

Vertical section of Fruit of Calamite, magnified.

"horse-tails" now growing in ditches, until you see them fifty and sixty (or more) feet high, and you would have the best restoration of these Calamites

that could be imagined. There were many species, characterized by fluted joints, and by difference of foliage. Here and there, but more sparsely scattered, were graceful tree-ferns, whose former fronds had left great scars on each side the trunk. The higher grounds were occupied by peculiar species of pine, bearing great berries as big as crab-apples. The

Transverse section of Fruit of Calamite, magnified.

humid morass was densely covered by a thick underwood of smaller ferns, which grew there in rank abundance. The equable temperature, rich soil, and humid atmosphere were just the needful accessories to the growth of vegetation of the class I have mentioned. It consequently flourished at a rate of which

we can form but a poor idea from the present. The accumulated trees, ferns, &c., were very great, and these gathered in immense quantities over the entire

Fig. 45.

area. I mentioned before that there was a slow sinking or submergence going on. Well, occasionally, the tides brought up silt and strewed it over the decomposing vegetation. In fact, many of the forests were actually buried thus, and their trunks are frequently met with standing erect in solid sandstone rock. But though the covering-up of the vegetation prevented the liberated gases from escaping, it also obstructed for a time the growth of other trees. The latter could not well flourish on sandbanks, and so they were limited to conditions elsewhere similar to those I have mentioned. But as time elapsed, the old circumstances returned. Another forest grew on the site of the older, to be buried up in its turn. During countless ages this alternate growth and covering-up went on, until in some places, as in the South Wales coal-field, there are no fewer than one hundred