THE SECONDARY EPOCH. 13 



feet. The secondary epoch can accordingly in all prob- 

 ability not have been half so long as the primary epoch. 



Just as Fishes prevailed in the primary epoch, Reptiles 

 predominated in the secondary epoch over all other verte- 

 brate animals. It is true that during this period the first 

 birds and mammals originated ; at that time, also, there 

 existed important amphibious animals, especially the gigan- 

 tic Labyrinthodonts, in the sea the wonderful sea-dragons, 

 or Halisaurii, swam about, and the first fish with bones were 

 associated with the many primaeval fishes (Sharks) and 

 enamelled fish (Ganoids) of the earlier times ; but the very 

 variously developed kinds of reptiles formed the predomi- 

 nating and characteristic class of vertebrate animals of the 

 secondary epoch. Besides those" reptiles which were very 

 nearly related to the present living lizards, crocodiles, and 

 turtles, there were, diu-ing the mesolithic period, swarms of 

 grotesquely shaped dragons. The remarkable flying lizards, 

 or Pterosaurii, and the colossal land-dragons, or Dinosaurii, 

 of the secondary epoch, are peculiar, as they occur neither 

 in the preceding nor in the succeeding epochs. The secondary 

 epoch may be called the era of Reptiles ; but on the other 

 hand, it may also be called the era of Pine Forests, or more 

 accui-ately, of the Gymnosperms, that is, the epoch oi plants 

 leaving naked seeds. For this group of plants, especially as 

 represented by the two important classes — the pines, or 

 Conifero}, and the palm-ferns, or Cycadece — during the 

 secondary epoch constituted a predominant part of the 

 forests. But towards the end of the epoch (in the Chalk 

 period) the plants of the pine tribe gave place to the leaf- 

 bearmg forests which then developed for the first time. 

 The fourth main division of the organic history of the 



