APPEARANCE IN TIME. 



Arthro- 



Coelentera. Echinoderma. Cephalopoda 



Quaternary or Post- 

 Tertiary. 



Pliocene. 



' 



Miocene. 



Eocene. 



Cretaceous. 



Jurassic. 



, 



.^ 



1- f 



u 



Triassic. 



c 



Permian. 







Carboniferous. 



Devonian or 

 Old Red Sandstone. 



CJ 



Silurian. 



( )rdovician. 



o 



Cambrian. 



Pre-Cambrian or 

 Archaean. 



