582 THE WONDERS OF GEOLOGY. Lect. V. 



jaws of very small animals are the sole indications of the 

 existence of Mammalia, and the bones of a species of 

 Wader, the only evidence of the presence of Birds. In 

 vain we seek for the relics of Man, or the remains of works 

 of art — for the skeletons of the Mastodon or the Mammoth 

 — of the Palaeotheria, or other mammalia that were their 

 contemporaries; the osseous remains of terrestrial and 

 fluviatile Reptiles alone appear. In the emphatic lan- 

 guage of Cuvier, "Nous remontons a un autre age du 

 monde — a cet age ou la terre rCetait encore parcourue que 

 par des reptiles a sang froid — ou la mer abondait en am- 

 monites, en belemnites, en terebratules, en encrinites, et ou 

 tous ces genres, aujourdliui d'une r arete prodigieuse, 

 faisaient lefond de sa population"* 



The earliest indications of air-breathing vertebrate ani- 

 mals are the reptiles, and the supposed imprints of their 

 footsteps, of the Permian system. In the succeeding epoch, 

 the Trias, colossal batrachians appear ; and on the sands of 

 that ancient ocean are found the foot-tracks of bipeds which 

 seem to point to a higher class, that of birds, for their 

 origin. In the following periods, embracing the deposition 

 of the Lias, Oolite, Wealden, and Chalk, swarms of rep- 

 tiles belonging to numerous genera every where prevail ; 

 species fitted to live in the air, on the land, in lakes and 

 rivers, and in the seas, — yet not one identical with any 

 existing form. These gradually decline as we approach 

 the close of the secondary, and are succeeded in the ter- 

 tiary, by as varied modifications of the higher animals, — the 

 mammalia and birds. Thus, the faunas of the vast periods 

 that intervened between the tertiary and palaeozoic ages, 

 present the following numerical relations in the three 

 higher classes of the vertebrata \\ — 



* " Ossemens Fossiles," tome v. p. 10. 



f This list of fossil reptiles is merely approximative ; the number 

 of genera and species is greater than here given. 



