The history of the primitive races of mankind, as far as we are able to trace it in the few relics that have survived their existence, shows us that an age of stone was followed by one of bronze, which in its turn was succeeded by one of iron. The Golden Age has probably never existed but in the fancy of poets who sought in the land of dreams a compensation for the deficiencies of the real world; and there can be no doubt that, despite California and Australia, our own times are as far from realising the pleasing vision as any before them. But a title to which they have a better claim is founded upon the vast use of the mineral fuel without which the glorious inventions of Watt and Stephenson would have been comparatively vain; and whoever has attentively examined the foundations of our industry, our commerce, our wealth, and our civilisation will hardly deny that we live in what may justly be termed the Age of Coal. This mineral, the importance of which in the political economy of the leading nations of the globe can hardly be overrated, is also one of surpassing interest in a geological point of view, for the history of its formation is one of the great marvels of the subterranean world. [Illustration: PECOPTERIS ADIANTOIDES.] [Illustration: SPHENOPTERIS AFFINIS.] The plants whose growth and decay originally furnished the materials of which our black coal[63] is composed, flourished in that far distant period when as yet no bird or mammalian quadruped had made its appearance, when even the gigantic Ichthyosaurus was not yet born, and the progress of organic life had not advanced beyond the creation of some uncouth reptiles or strangely formed fishes. From the vast space of time which separates us from the carboniferous age, it may easily be imagined that the state of the vegetable world was then extremely different from that now prevailing. The vegetable remains which constitute coal have generally been so transformed as to afford no trace of their original texture; yet the distinct plants found here and there preserved in the mass, and which amount to about five hundred species, plainly bear the character of a swampy vegetation, and show that they must have grown in submerged, or at least extremely humid, situations. They consist chiefly of ferns, of Lepidodendra, allied to the club- mosses of the present day, of a few coniferous trees, the woody structure of some of them showing that they were related to the Araucarian division of pines, more than to any of our common European firs; of some large ‘horsetails,’ and of Sigillariæ and Calamites, that seem to have been distinct from all tribes of now existing plants. Scanty as are these relics of an extinct world, they yet allow the fancy to reconstruct the forests of which they formed a part, and to wander through those dismal woods where generations after generations of arborescent ferns and moor-plants flourished and decayed for the use of