cir. XL. SUCCESSION OF ANIMALS. 423 



footprints of some animal with feet ; and the bones of an 

 amphibian, somewhat like a frog, are next found. In these 

 times the fish began to cease to be monarchs of the water, for 

 a little higher up huge swimming reptiles, like our crocodiles 

 and lizards, but much larger, have left their bones in the 

 rocks. Next come reptiles with wings, which measure six- 

 teen feet across from tip to tip, and we must picture these 

 huge flying lizards, with wings like bats, roaming over the 

 globe with no higher animals to persecute them. 



But they were only to have their turn, for in rocks formed 

 a little later there appear two skeletons, one of a small crea- 

 ture half reptile half bird, about the size of a pigeon, and the 

 other of a real bird with some of its feathers still remaining ; 

 and in beds of about the same age there occurs the jaw of 

 a small insect-eating animal something like an ant-eater. 

 Birds and quadrupeds therefore had now begun to exist, and 

 soon the bones of pouched animals are found, and then of 

 mammalia, like our moles and shrews ; and from this time 

 the reptiles become smaller, as if they were kept down 

 and gradually destroyed by the higher animals, and the 

 quadrupeds become larger and more powerful ; till, in those 

 beds which Cuvier studied near Paris, we find the gigantic 

 elephant and rhinoceros-like animals we spoke of before ; 

 while in beds of about the same age occur the first bones of 

 monkeys. 



This is a very rough sketch of the order in which ani- 

 mals are found in the earth's crust. The lower kinds first, and 

 then gradually higher and higher forms as they come near to 

 our own time*; and if we could study them more closely you 

 would see that in rocks nearly of the same age the forms 

 are always very like each other, while the farther apart the 

 formations are. the more different are the animals. It is true 



