38 THE HISTORY OF CREATION. 
like the historian who divides the history of nations into 
the three main divisions of Antiquity, the Middle Ages, and 
Modern Times, and each of these sections again into subordi- 
nate periods and epochs. But the historian by this sharp 
systematic division, and by fixing the boundary of the 
periods by particular dates, only seeks to facilitate his 
survey, and in no way means to deny the uninterrupted 
connection of events and the development of nations. 
Exactly the same qualification applies to our systematic 
division, specification, or classification of the organic history 
of the earth. Here, too, a continuous thread runs through 
the series of events unbroken. We must therefore dis- 
tinctly protest against the idea that by sharply bounding 
the larger and smaller groups of strata, and the periods 
corresponding with them, we in any way wish to adopt 
Cuvier’s doctrine of terrestrial revolutions, and of repeated 
new creations of organic populations. That this erroneous 
doctrine has long since been completely refuted by Lyell, I 
have already mentioned. (Compare vol. i. p. 127.) 
The five great main divisions of the organic history of 
the earth, or the paleontological history of development, 
we call the primordial, primary, secondary, tertiary, and 
quaternary epochs. Each is distinctly characterized by the 
predominating development of certain animal and vegetable 
groups in it, and we might accordingly symbolically desig- 
nate the five epochs, on the one hand by the names of the 
croups of the vegetable kingdom, and on the other hand by 
those of the different classes of vertebrate animals. In this 
case the first, or primordial epoch, would be the era of the 
Tangles (Algze) and skull-less Vertebrates; the second, or 
primary epoch, that of the Ferns and Fishes; the third, or 
