mites-were doubtless thirty feet in height. The impressions of their huge and prostrate stems may often be traced upon the shale which overlies a seam of coal. Of ferns, no species living in temperate latitudes attains the dimensions of a tree; but there formerly flourished within the limits of the Northern States ferns which attained to arboreal dimensions, single fronds of which reached the length of six to eight feet. The club-mosses-Lepidodendra-of the same epoch grew to the magnitude and aspect of stately palms (Fig. 66). Among us they trail upon the ground, or rise but a few inches above it. The largest living club

11 FLEATION

:: feet in height. The stems of the time the leaves, were covered miled, and are often mistaken by

Shake The cones of these a' unuance in Olia Another cuslashed spied Sia Their 1st lett 11 Lismeter, Lave somefeet in length. The flutDa series of pits, like the ISTAes these tree-tranks Mari Vit Standing by For. Below are the - the

mosses do not exceed three feet in height. The stems of Lepidodendron, after the falling of the leaves, were covered with scars diagonally arranged, and are often mistaken by the uninformed for "petrified snakes." The cones of these plants are found in great abundance in Ohio. Another curious form of this period has been styled Sigillaria. Their fluted trunks, from one to five feet in diameter, have sometimes been seen sixty and seventy feet in length. The flutings are marked by a longitudinal series of pits, like the impressions of a seal. In many instances these tree-trunks have been found erect, evidently buried while standing by accumulations of sand and mud (Fig. 67). Below are the roots and rootlets-formerly called Stigmaria-and the very soil remaining in which they flourished. In the excavation of a bed of coal these petrified tree-trunks are not unfrequently cut off below, when the slight taper of the stem permits them to slide, by the force of gravity, down into the mine. These "coal-pipes" are much dreaded by the English miners, for almost every year they are the cause of fatal accidents. "It is strange to reflect," says Sir Charles Lyell, "how many thousands of these trees fell originally in their native forests, in obedience to the law of gravity, and how the few which continue to stand erect, obeying, after myriads of ages, the same force, are cast down to immolate their human victims."

Let the reader embody before his mind's eye a group of rush-like and fern-like trees and under-shrubs, interspersed among gigantic club-mosses and occasional conifers, and he has a picture of a carboniferous jungle-a jungle not enlivened by the tread of quadrupeds or the singing of birds, but mute as the solitudes of an African desert-voiceless save when the alligator-like bellowings of the Archegosaurus in a neighboring bayou waked the echoes of those gloomy corridors, and startled the lesser amphibia from