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 primeval 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, during 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 
accurately, of the Gymmnosperms, that is, the epoch of plants 
having naked seeds. For this group of plants, especially as 
represented by the two important classes—the pines, or 
Coniferw, and the palm-ferns, or Cycadee—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- 
bearing forests which then developed for the first time. 
The fourth main division of the organic history of the 
