CARBONIFEROUS ERA. 



Ill 



from the fish proper to these labyrinthodont reptiles that 

 come boldly into force in the Permian and triassic eras. 



Fin Spines: 1, Pleuracanthus ; 2, Gyracanthus . 3, Ctenacanthus. Palatal Teeth: 



4, Ctenoptychius ; 5, Psammodus ; 6, Poecilodus. 7, Jaw of Rhizodus, 



showing Reptilian Teeth. 



The course of vitality is thus for ever onward and upward 

 onward in the introduction of forms having more varied 

 geographical adaptations, and upward in the manifestation 

 of higher physiological and functional performance. 



Such is the panorama of carboniferous life an unparal- 

 leled exuberance of endogenous flora ; a wonderful profusion 

 of estuarine and marine life in all its aspects : but as yet 

 few insects, none of the higher reptiles, no birds, no mam- 

 mals ! And yet, looking at mere external conditions, it is 



