i 3 6 



Mammals 



ZOOLOGY. 

 FlG. 64. 



'Birds 



10000 



Reptiles 



3000 



mphibians 



Mollusks 

 Tunicata, etc. ( 25000 



v 



Coelenterates 



r 



Protozoa 



4000 



FIG. 64. Diagram showing the general relations of the chief divisions of the animal 

 kingdom. The number of species belonging to each is roughly approximate, only. 



172. Reptiles. This is a class recognized by zoologists 

 which is not nearly so easy to define or to identify as either of 

 the preceding. This is partly because the animals composing 

 it differ more among themselves than in the other classes. It 



