APPEARANCE IN TIME. 79 



Ccelentera. Echinoderma. ^"j™" Cephalopoda. 



Quaternary or Post- 

 Tertiary. 



£3 



Pliocene. 



g Miocene. 



Eocene. 





"SI 



Cretaceous. 



Jurassic. 



Triassic. 



Permian. 





$' 



Carboniferous. 



Devonian or 

 Old Red Sandstone, 



Silurian. 



Ordovician. 



Cambrian. 



Pre-Cambrian or 

 Archaean. 



