4 STORY OP THE AMPHIBIANS 



cause both were cold-blooded creeping things ; but 

 although a lizard and a salamander may look much 

 alike, mere resemblance is no longer a basis of classi- 

 fication. Kinship is a matter of structure. 



While the fishes were the first creatures to have 

 a backbone, the amphibians were the first to take this 

 great weapon and go out to conquer the dry land. 



Fig. 2. — Giant salamander {Megalotatrachus maximua). 



They were thus the pioneers of all the reptiles and 

 mammals, which have since subdued the earth, and 



