Yet they can often remain for a long time both under water and under ground, for they are still cold-blooded animals, breathing very slowly, and easily falling into a state of torpor when the air around them is cold and chill. They are but the first step, as it were, to active land-animals; yet they have played a great part in the world, and when we know their history we shall be surprised to find how much Life has been able to make of her cold-blooded children. To learn how this has been, however, we must travel away from home and our own surroundings. The tiny brown lizard which runs over our heaths, while its legless relation, the slowworm, burrows in the ground,--the few snakes which glide through the grass of our meadows, and the stray turtles thrown at rare intervals on our shores,--tell us very little about true reptile life. It is to Africa, India, South America, and other warm countries, that we must go to find the formidable crocodiles, huge tortoises, large monitor-lizards, and dangerous boa-constrictors, cobras, and rattle-snakes. And even then, strong and powerful as some of these creatures are, they do not tell us half the history of the cold-blooded air-breathers. For the day of reptile greatness, like that of the sharks and enamel-scaled fish, was long long ago. Now that we know how frogs pass from water-breathing to air-breathing, and how axolotls, accustomed to live all their life in the water, can lose their gills and become land-animals, we can form an idea how in those ancient days, while still the huge-plated newts were wandering in the marshes, some creatures which had lost their gills would take to the land, and their young ones starting at once as air-breathers, as the black salamanders do now (see p. 80), would in time lose all traces of the double or _amphibian_ life, and become true air-breathing reptiles. At any rate, there we find them appearing soon after the coal-forest period passed away, at first few and far between, in company with the large amphibians, but spreading more and more as the ages passed on, till they in their turn became monarchs of the globe. Already, when the coal-forests had but just passed away, a lizard,[65] in some points like the monitors that now wander on the banks of the Nile, was living among his humbler neighbours; and from that time onwards we find more and more reptiles, till just before the time when our white chalk was being formed by the tiny slime-animals at the bottom of the sea, we should have seen strange sights if we could have been upon the globe. For the great eft was no longer “... lord and master of earth.”