354 



ANIMAL LIFE 



gill arches and an entire circulatory system, strikingly 

 similar to the same structures in the fish. The brain is 

 fishlike also. In some young birds taken from the egg, 



FlG. 396. Fore limbs of vertebrates showing similarity of structure. A, sala- 

 mander ; B, turtle ; C, very young bird ; Z>, adult bird ; E, dog ; F, man. 



the wing strongly resembles in structure the limb of a 

 lizard. 



These facts, cited in the preceding paragraphs together 

 with much other information discovered by the zoologist 

 and geologist, lead to the conclusion that at first there 

 existed on earth only a few forms of simple life similar to 

 the amoeba, and from these acted on by the rapid changes 

 of climate, soil, water, and food, have arisen all the varied 

 forms of animal life. 



