THE LEWIS BROOKS MCTSEUM. 41 



The ferns are now greatly multiplied, and towards the close 

 of the age many become arborescent. The types of Lepido- 

 dendron, Sigillaria and Calamites, reach their culmination 

 here, then decline and perish in the next period, the Per- 

 mian. The same may be said of a vast number of other 

 forms. Tne gymnosperms became multiplied in genera 

 and species. Forms appear allied to the true conifers, now 

 so abundant on the earth. The vegetation was -so luxuriant 

 that its remains furnish us with most of the coal we now 

 use. The Permian period is properly the close of the Car- 

 boniferous age, when most of the Protozoic vegetation per- 

 ished, and where some of the forms destined to abound in 

 the next following Mesozoic time, first make their appear- 

 ance. Every fact indicates that in the Protozoic time the 

 water predominated over the land much more than at pre- 

 sent. The surface features of the earth were much simpler, 

 the land was lower, being largely composed of bogs and 

 marshes. There were no zones of climate, and the same 

 vegetation flourished everywhere. It indicates that the 

 climate was warm and moist, and that the air was heavily 

 charged with vapor of water and with carbonic acid. There 

 was no bright sunshine, and hence no flowering plants ex- 

 isted, and no trees with organs and foliage like our modern 

 forest growths. The vegetation consequently had a monoto- 

 nous and gloomy aspect in keeping with the rest of nature. 

 Most of the plants were of compound character and of com- 

 paratively low grade. 



The extensive destruction of plant life in the Permian 

 was caused by the great changes which took place then on 

 the earth's surface. These lifted up and laid dry great 

 areas of land, and unfitted it for the growth of the Proto- 

 zoic vegetation. The sun too now began to make its influ- 

 ence more powerfully felt, to the detriment of shade-loving 

 plants. We have an example of these great movements of 

 the earth in the United States, for the great Appalachian 

 upheaval, which formed the Alleghany mountains, and 



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