FIRST TRIASSIC PERIOD. 



periods. Since the Permian stage in Russia is not overlaid by the 

 Triassic, it follows that the Swedo-Russian continent, at the com- 

 mencement of the Tri- 

 assic age, extended over 

 all northern Russia, 

 from the Baltic to the 

 Ural Mountains, and 

 from the shores of the 

 Frozen Ocean to the 

 government of Saratov. 

 310. A great change 

 was produced in the 

 character of the vege- 

 tation compared with 

 that of the former pe- 

 riods. The arborescent 

 ferns and tall equise- 

 tacean trees which pre- 

 vailed in such lavish 



profusion in the latter Fig. 146. Map of France in the Triassic age. 



periods of the Palaeozoic 



age, now existed in greatly diminished numbers, while the conifers 

 and plants, analogous to thezamias and the cycadese, figs. 147, 148, 

 formed an important feature of the flora, preluding the immense de- 

 velopment which these classes underwent in the succeeding periods. 



FIRST TRIASSIC PERIOD. 



311. By the catastrophe which terminated the Palaeozoic age, 

 ninety- one species of Mollusca and Radiata, besides all the 

 existing species of the superior classes, were destroyed, never to 

 re-appear upon the earth. Seventeen generic forms also became 

 extinct. When tranquillity was re-established, and land and 

 water again became fitted for the maintenance of organised life, 

 Almighty Power called into existence thirty-six new generic animal 

 forms, and revived thirty-three, which formerly lived, making a 

 total number of sixty-nine genera in the new animal kingdom. 

 Independently of the species of the higher classes of animals, not 

 so exactly ascertained, the genera of Mollusca and Radiata alone 

 consisted of 107 species, * which have been catalogued and described. 



The marine littoral and fluviatile deposits have supplied the 

 means of tracing the shores of the seas of this period, and prove 

 them to have been subject to the same atmospheric and tidal 

 influences as those which afiect the seas and oceans of the present 



* "Prodrome d'Orbigny," vol. i. pp. 171173. 



61 



