“Is it possible to distinguish the forms of plant-life whence has come our coal? Yes, it is possible, so well preserved are the details of that life in the products of our mines. Now an examination of the imprints left to us in the laminæ or leaves of our stone book shows us that the plant-life of those remote ages in which the coal was accumulated bore not the least resemblance to that of our present forests. And this difference was to be expected. The animal life has changed; why, then, should the plant-life have remained unaltered?” “Didn’t they have trees then like ours?” asked Jules. “No,” replied his uncle; “we do not find in our coal mines any signs of the existence of trees resembling those of our day. Nowhere in the world, in fact, are there now to be seen any such forms of plant-life as flourished so abundantly in those remote ages; or if any still exist that are at all analogous, they must be sought in the islands of the tropical seas. No vegetable growth of that coal epoch, whether tree or bush or simple cluster of leaves, bore flowers. The splendors of the corolla were not to appear until a later period. “For the most part there were only tall stems or stalks, without branches, of equal size from top to bottom, and furrowed with channels or dotted with large points arranged in spiral lines. At the top a tuft of enormous leaves balanced itself, the under surface of each leaf bearing elongated or rounded swellings containing a fine brown dust, each grain of which was a seed for the propagation of the plant. “Plants that thus bear their seeds, or spores, in powdery masses on the under side of the leaves are called ferns. A number of species flourish in our part of the world. They are unpretentious plants, fond of shade and coolness. Old damp walls, rocks that drip water drop by drop, the darkest corners of our woods—these are the customary haunts of the fern. “A short underground stock and a sparse cluster of leaves, very elegantly shaped, it is true, constitute our native ferns. Those of the coal epoch were of a different pattern. Some of them displayed at the top of a stem as tall as our poplars a cluster of leaves five or six meters in length. They are called tree-ferns, and they contributed the greater part of the coal-forming material. “The accompanying illustration will give you an idea of what the vegetation of that period must have looked like. What strange trees! How different from our oaks and maples and hemlocks! The soil is a liquid mud in which lie and rot the tree-trunks prostrated by the weight of years; the air is sultry, moist, heavy, strongly impregnated with a moldy smell; and the density of the foliage barely admits a few sunbeams to flicker over the surface of the stagnant pools.