242 



SYSTEMATIC BOTANY. 



1. Monocotyledones. — Graminese, Cyperacese, Lili- 

 acese, Naiadacese, Scitaminese, Dioscoreacese, and Palmaoese. 



2. Dicotyledones. — Salicacese, Cupuliferse, Lauracese, 

 Urticaeeae, Ericacese, Ebenacese, Platanacese, Araliacese, 

 Bosacese, Sapotacese, and Magnoliacese. 



205. In .the Mammalian Age, which includes the 

 Tertiary and Quaternary Periods, the vegetation is de- 

 cidedly more modern than in the preceding. In the 

 Tertiary Period nearly all the genera of the Palms, 

 Grasses, and Dicotyledones (Fig. 347) were the same as 

 now, though most of the species are extinct. The Diatoms, 

 too, existed in great abundance ; and immense deposits, con- 

 sisting wholly of their silicious shells or valves (frustules), 

 are found in the Tertiary Period. The celebrated Bohe- 

 mian deposit in Europe is fourteen feet thick, and Ehren- 



berg estimated that every cubic 

 inch of the material contains 

 forty billion shells. The Rich- 

 mond deposit in Virginia is thirty 

 feet thick, and many miles in 

 extent. The Mosses {Bryophyta) 

 land the Protophyta very likely 

 existed before this time, but they 

 347 have not been found in rocks 



lower than the Tertiary. In the Quaternary Period the 



plants were almost wholly identical with those now living. 



In this period, too, man is supposed to have appeared on 



the earth. 



206. The Age of Man, or the present time, exhibits a 

 vegetation of a higher type than the preceding ages, and 

 the species are exceedingly numerous. All countries are 



Fig. 347. Pltttanus aceroides (Manhattan Age). 



