SECONDARY EPOCH.
During the Primary Epoch our globe would appear to have been chiefly appropriated to beings which lived in the waters—above all, to the Crustaceans and Fishes; during the Secondary Epoch Reptiles seem to have been its prevailing inhabitants. Animals of this class assumed astonishing dimensions, and would seem to have multiplied in a most singular manner; they were, apparently, the kings of the earth. At the same time, however, that the animal kingdom thus developed itself, the vegetation lost much of its importance.
Geologists have agreed among themselves to divide the Secondary epoch into three periods: 1, the Cretaceous; 2, the Jurassic; 3, the Triassic—a division which it is convenient to adopt.