CHAP, xiii The Past History of Animals 



209 



Primary or Palaozoic 



O 





o 



Si 

 § 



U 

 en n> 



>i 

 B 



c : 



'Ti 



Secondary or 

 Mesozoic 



O 



w: 



Tertiary or 

 Cainozoic 



H 



S 2 



o s 



.A 3i.. 



