like swimming fish-eating ostriches, for their breastbones were flat, not thin and sharp like the sparrow’s, and they had scarcely any wings, short tails, long slender necks, and jaws full of teeth, this time set in grooves like those of lizards and snakes. In these and many other points the early birds came very near to the reptiles--not to the flying ones, but to those which walked on the land. And now, perhaps, you will ask, did reptiles then turn into birds? No, since they were both living at the same time, and those reptiles which flew did so like bats, and not in any way like the birds which were their companions. To explain the facts we must go much farther back than this. If any one were to ask us whether the Australian colonists came from the white Americans or the Americans from the Australians, we should answer, “neither the one nor the other, and yet they are related, for both have sprung from the English race.” In the same way, when we see how like the ancient birds and reptiles were to each other, so that it is very difficult to say which were bird-like reptiles and which were reptile-like birds, we can only conclude that they, too, once branched off from some older race which had that bone between the jaws, that single neck joint, and the other characters which birds and reptiles have in common. But long ago they must have gone off each on their own road, the reptiles filling the world for a time, flying and walking and swimming, till they found at last that creeping was their most successful way of life; the birds on the other hand becoming more and more masters of the air and the water, so that, while keeping the same bones and parts as the reptiles, they have grown into quite different beings in their form and habits, giving up the long-jointed tail of the _Archœopteryx_, or ancient-winged bird, for the compact feathered fan which helps to balance them in their flight, and the teeth of the water-birds for the sharp and horny beak, which, together with their claws, is their chief weapon of attack and defence now that they have employed their front limbs as wings. Nor shall we have far to look for the secret of their success in life. Just as the reptiles have an advantage over the naked frogs and newts by having strong scaly coverings in their skin, so the birds have an advantage over the reptiles in that beautiful feathery plumage which covers their body, and the powerful muscles which work their limbs. For it is by means of these that they have been able to move quickly and travel far, and to develop that bright nervous intelligence which has grown more and more active as they have been carried into fresh scenes and experiences, overcoming new difficulties and enjoying new pleasures.