“Is that why we sometimes find things that look like fern-leaves in coal?” queried Perry. “Yes, yes, they are fern leaves, for in the Coal Forests were many kinds of primitive ferns. “Then came the Permian revolution,” and Antoine’s nimble fingers began to put the clay in great masses on his board. “Real mountain ranges began. The swamps awoke from the dark sleep of the Coal-Forest time and reared themselves into plateaus, the shallow seas were hurled into deeper beds, and though the Mediterranean again became a sea, yet there was even more land surface then than there is to-day. “With this upheaving, came the First Age of Cold. The coal-forests died, the pine-trees took their places. The marshes became plains. Nearly all species of life belonging to that warm age died. The Empire of the Fishes and Amphibians ended. The Mediterranean slowly diminished in size and again became an inland sea, while in Europe to the north, Africa to the south and in America, beyond the Atlantic, the Empire of the Reptiles began. “The Middle Ages of the Earth had come, known as the Mesozoic Era. The Mediterranean held its place as an inland sea, as one might well expect, since it was sea during the Permian times when most of the world was high, but all through the Triassic—which is the first Period of the Mesozoic Era—the land began to fall, and before it was over, the Mediterranean joined the Atlantic once again. Slowly the land fell further, the sea spread out vast arms of warm water; plants and animals increased. By the Jurassic Period there was marsh again from Norway to Africa and the huge dinosaurs became the masters of the world, living on the islands and peninsulas in the midst of that shallow tropical sea. “Yet the slow death of cold which had awaited the Fishes and Amphibians in the Permian Revolution was awaiting the Reptiles also. The Second Age of Cold was near. After the Cretaceous Period, the land began to rise, until, when hundreds of thousands of years had elapsed, the northern part of Europe was elevated, the Mediterranean lost its opening to the ocean, and became once more an inland sea. Then came the Second Ice Age, the second cataclysm of want and death. The Pterodactyls died away completely, the huge reptile monsters fell by thousands and all the giant Saurians had to give place to the warmer-blooded mammals. “So came the Age of New Life, the Cenozoic Era, of which only the first portion or the Tertiary Period concerns us now. During the Eocene Epoch began the leveling and wearing away of the land raised at the end of the Age of Chalk. Almost to the Equator, Africa was flooded. Italy, Turkey, Southern Russia and Asia Minor sank. The Atlantic and the Pacific joined then, as they would not be joined again for millions of years to come, when Man should pierce an isthmus at Panama.