“A monstrous eft was of old the lord and master of earth, For him did the high sun flame, and his river billowing ran. And he felt himself in his force to be Nature’s crowning race;” for they show us huge and powerful creatures[60] which sported in the water or wandered over the land with sprawling limbs, long tails, and bones on which gills grew, while their heads were covered with hard bony plates, and their teeth were large, with folds of hard enamel on the surface. Some of these were fish-like, with short necks and broad flat tails, but they had true legs and toes; others, more like crocodiles, and sometimes ten feet long, were able to walk firmly, but still dragging their bodies and long tails over the swampy ground on which their footprints are still found; some were small and more like lizards, with simple teeth, scaly armour, and light nimble bodies; and these, probably, ran about quickly on the land, and have sometimes left their skeletons in the hollow trunks of the old coal-forest trees. All these plated and formidable creatures were _amphibia_ or double-lived animals, and this was _their_ Golden Age, as they preyed upon the fishes in the swamps and ponds, probably not sparing even their nearest connections, the mud-fishes, who, less fortunate than themselves, had followed the road of fish-life instead of coming out upon the land. They lived so long ago that we can tell but little of their daily lives, but it is clear that they played a very different part from our small frogs and newts of to-day, and in their well-formed limbs were worthy forerunners of land and air-breathing animals. But like the old race of fishes these large amphibians were only to have their day, for as other branches of the family tree grew up, and reptiles grew strong and mighty, and other true land animals began to flourish, these huge plated forms dwindled away, and we lose sight of them; and when we find any of their relations again it is only as our present frogs and newts, salamanders and cæcilians, which have taken up their refuge in lakes, ponds, ditches, underground waters, or damp mud. And, curiously enough, those forms of to-day which are most like the huge _Labyrinthodonts_,[61] as they are called, of the old coal-forests, are the feeble cæcilians, with their horny scales and their numerous ribs, although they have now fallen the lowest of all amphibians, and, with their sightless eyes and ringed and legless bodies, have taken to burrowing in the ground like worms.