AGES OF NATURE. 



223 



Let us review each of these four Ages of Nature, with 

 reference to the diagram at the beginning of the volume. 



470. THE PALEOZOIC AGE. Reign of Fishes. The 

 palaeozoic fauna, being the most remote from the present 

 epoch, presents the least resemblance to the animals now 

 existing, as will easily be perceived by a glance at the fol- 



Fig. 155. 



lowing sketches, (Fig. 155.) In no other case do we meet 

 with animals of such extraordinary shapes, as in the strata 

 of the Palaeozoic age. 



471. We have already stated (466) that there are found, 

 in each formation of the primary age, animal remains of all 

 the four great departments, namely, vertebrates, articulata, 

 mollusks, and radiata. We have now to examine to what 

 peculiar classes and families of each department these re- 

 mains belong, with a view to ascertain if any relation between 



