CAEBONIGENOUS ERA. 45 



upon it. M. Agassiz has satisfied himself that this was the 

 nature of the organization of the early fishes, as it is that of 

 the sturgeon of the present seas. 1 



An eminent geologist is of opinion that the species of this 

 era vary locally, as far as might be expected from what we 

 see of the distribution of animal life in the present times. 

 Nevertheless, throughout the distant parts of the earth where 

 Devonian strata are found, the general characters of animal 

 and also vegetable life are nearly the same. It is further ob- 

 served, that whatever particular family is continued with little 

 change through a succession of strata, is also amongst those 

 most widely extended over the world. It was the opinion of 

 M. Brongniart, who distinguished himself by his investigation 

 of vegetable fossils, that the fuci of these early seas indicate a 

 higher temperature than now prevails at many of the places 

 where they are found. He regarded this as a proof of the 

 more equable diffusion of a tropical climate in ancient times, 

 and distinctly attributes it to the action of the internal heat 

 of the earth. 



As yet overlooking, for the present, certain partial and 

 newly-announced instances we meet with no traces of land 

 plants. The hitherto esteemed exclusively marine character 

 of the flora and fauna of the early ages was thought to betoken 

 the non-existence of dry land. But there are reasons apart 

 from the fossil history for believing that great masses had been 

 exposed to the atmosphere in those ages. The earliest strata 

 give token of vast disintegration. In our time, this process 

 is usually seen taking place chiefly in the atmosphere, and at 

 the point where land and water meet ; in a much less activity 

 below the surface of the ocean. It would thus appear likely 

 that there was dry land in the eras of the earliest stratified 

 formations, though, from whatever cause, it bore no vegetation 

 and sustained no animals, or was only a scene of life in certain 

 rare and favourably situated places. 



CAEBONIGENOUS ERA. LAND PLANTS AND ANIMALS. 



THE next group of rocks is called the Carboniferous Forma- 

 tion, from the remarkable feature of its numerous interspersed 



1 Some remarks on the grade of the Devonian fishes appear after- 

 wards. 



