RETROSPECT OF PALEOZOIC AGE. 



above the Carboniferous seas, and surrounded east and west by 

 the waters of the Permian seas. 



291. The Ural chain was also further heaved upwards, so as 

 to form the series of mountains which now exist. In South 

 America the continents were also considerably increased in extent 

 in the west. The Chiquitean chain extended over some hundred 

 leagues, from Brazil to the eastern extremity of the Andes. 

 South America appears then to have had the form of a vast tri- 

 angle, the length of which, from north to south, extended over 

 35 of latitude. 



While the land underwent but little change in France, it was 

 enlarged both in England and Russia, towards the east, by a 

 considerable portion of the Carboniferous stage not covered by 

 the waters of the Permian sea. 



292. The fauna of this period were almost exclusively marine, 

 a few, perhaps, being fluviatile. The two genera of reptiles were 

 both fluviatile and marine. The fishes belonged to the Placoid 

 and Ganoid families, of which the shark and sturgeon are living 

 examples. Among the Mollusca, certain species of oysters first 

 appeared in this period. 



293. Although the organic remains present no traces of land 

 animals, it is nevertheless probable that they prevailed upon the 

 continents at least as extensively as in the previous period. 

 M. Brongniart considers the vegetable fossils of this period to hold 

 an intermediate place between those of the previous and succeed- 

 ing periods. The marine fauna found in the Old and New World 

 from the line to the 80 of latitude being identical in its character, 

 demonstrates that central heat still neutralised the effects of solar 

 radiation, so as to efface all isothermal lines, and that over the 

 entire globe a tropical climate prevailed. 



294. This period, like the others, was tormented by geological 

 convulsions, of which the traces are found in the discordance of 

 the stratification and the increased elevation of the immense 

 surface constituting the Permian formation in Russia, in the 

 dislocation which produced the Netherlaiid range of mountains 

 and those of South Wales. The effects of these geological pertur- 

 bations are altogether in accordance with the superior limits of 

 the fauna and flora of the Permian stage. 



RETROSPECT AND RECAPITULATION OF THE PAL2EOZOIC AGE. 



295. With the Permian period was closed the Palaeozoic age. The 

 first assemblage of animated beings which peopled the earth in- 

 cluded types of all the principal divisions of animal forms, but those 

 of the lowest class most abounded. Thus, three animal and vege- 



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