370 



ZOOLOGY 



Photograph by E. R. Sanborn, N. F. Zool. Soc. 

 FIG. 147. American alligator (Alligator mississippiensis). 



widespread, occurring in Europe and Asia. It used to 

 be supposed that there were no living Old World alli- 

 gators, but in 1879 a species was described from China. 

 The species of living crocodiles are relatively numerous, 

 and are known on both sides of the world. 



Lizards 8. The lizards, or Lacertilia, are extremely numerous 



' and widely distributed over the earth. The ordinary 

 forms are scaly, and possess four well-developed legs, 

 but there are strangely modified lizards without legs 

 and even without distinct scales. In such cases the 

 structure of the skull serves to indicate that they are of 

 the lizard group, and not the snakes they seem to be. 

 The snakelike form has been developed independently 

 among the fishes (eels), lizards, and true snakes. The 

 Gila (pronounced hee'la) monster (Heloderma) of Arizona 

 is a poisonous lizard, and appears to possess "warning 

 coloration," dark brown and orange. The chameleons 

 are African arboreal lizards, famous "for their power of 

 changing color. This is done through the movements 



