190 GEOLOGICAL SUCCESSION OF ANIMALS. 



precedes, than to those of the carboniferous formation, which 

 is much more ancient ; and in the same manner, the fossils 

 of the carboniferous group approach more nearly to those of 

 the Silurian formation, than to those of the Tertiary. 



468. These relations could not escape the observation of 

 naturalists, and indeed they are of great importance for 

 the true understanding of the development of life at the sur- 

 face of our earth. And, as in the history of man, several 

 grand periods have been established, under the name of 

 Ages, marked by peculiarities in his social and intellectual 

 condition, and illustrated by cotemporaneous monuments, 

 so, in the history of the earth also, are distinguished several 

 great periods, which may be designated as the various Ages 

 of Nature, illustrated in like manner by their monuments, 

 the fossil remains, which, by certain general traits stamped 

 upon them, clearly indicate the eras to which they belong. 



469. We distinguish four Ages of Nature, corresponding 

 to the great geological divisions, namely : 



1st. The Primary or Paleozoic Age, comprising the lower 

 Silurian, the upper Silurian, and the Devonian. During this 

 age there were no air-breathing animals. The fishes were 

 the masters of creation. We may therefore call it the Reign 

 of Fishes. 



2d. The Secondary Age, comprising the carboniferous 

 formation, the Trias, the oolitic, and the cretaceous forma- 

 tions. This is the epoch in which air-breathing animals first 

 appear. The reptiles predominate over the other classes, 

 and we may therefore call it the Reign of Reptiles. 



3d. The Tertiary Age, comprising the tertiary formations. 

 During this age, terrestrial mammals, of great size, abound. 

 This is the Reign of Mammals. 



4th. The Modern Age, characterized by the appearance 

 of the most perfect of all created beings. This is the Reign 

 of Man. 



