PROGRESS OF THE BACKBONED FAMILY. 74.5 



types tortoises, lizards, crocodiles, and snakes should have managed 

 to find room to live among the myriads of warm-blooded animals 

 which have filled the earth. These four groups have made a good 

 fight of it, and many of them even make use of warm-blooded animals 

 as food. The tortoises, it is true, feed upon plants, except those that 

 live in fresh water, and feed chiefly on fish, snakes, and frogs, while 

 most of the lizards are insect-feeders. But the crocodile, as he lurks 

 near the river's edge, and the snake, when he fastens his glittering 

 eye on a mouse or bird, are both on the lookout for animals higher in 

 the world than themselves. 



AVe come now into quite a new life, for we are going to wander 

 among the conquerors of the air, who have learned to rise far beyond 

 our solid ground, and to soar, like the lark, into the clouds, or, like the 

 eagle, to sail over the topmost crags of the mountains, there to build 

 his solitary eyrie. 



In those far by-gone times, when the huge land-lizards browsed 

 upon the trees, the birds living among them were much more like them 

 in many ways than they are now. Of water-birds there were some 

 about the size of small gulls, which flew with strong wings and had 

 fan-shaped tails, but had teeth in their horny jaws, set in sockets like 

 those of the crocodile, while their backbones had joints like those of 

 fishes rather than birds ; and with them were other and wingless birds 

 rather larger than our swans, but more like swimming, fish-eating 

 ostriches. 



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 further 

 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 rep- 

 tiles and which were reptile-like birds, we can only conclude that they, 

 too, once branched off from some older race which had that bone be- 

 tween the jaws, that single neck-joint, and the other characters which 

 birds and reptiles have in common. 



But where have the feathers come from those wonderful, beau- 

 tiful appendages without which the bird could not fly? They are 

 growths of his skin, of the same nature as the scales of reptiles, or 

 those on the bird's own feet and legs ; and on some low birds, such as 

 the penguins, they are so stiff and scale-like that it is often difficult to 

 say where the scales end and the feathers begin. All feathers, even 



