Plants of Past Ages. 355 



smaller forms of ferns occurred in great abundance, and 

 the genus Equisetum appeared with representatives whose 

 stems grew to be four inches in diameter. 



225. Jurassic Plants. In the Jurassic the Cycads ap- 

 pear to have reached their highest development, occurring 

 as far north as Greenland and Spitzbergen, whereas at the 

 present time they are restricted to the warm regions of 

 Mexico, the West Indies, Florida, Africa, and India. The 

 conifers of this period were more like those of the present 

 time. There is some evidence that Monocotyledons had 

 already been evolved before the close of this period. The 

 fact that ants, bees, wasps, flies, and possibly butterflies 

 appeared at this time affords collateral evidence that the 

 flowering plants were already at hand to supply food in 

 the form of pollen and nectar. 



226. Cretaceous Plants. The beginning of the Creta- 

 ceous period is noted for the apparently sudden appear- 

 ance of the noble Sequoias of twenty-six species ; and of 

 Dicotyledons, represented by the Sassafras, poplars, and 

 Rhododendrons. By the middle of the Cretaceous period a 

 characteristically modern flora had been evolved, repre- 

 sented, in addition to the trees named above, by the wil- 

 lows, oaks, maples, elms, beeches, chestnuts, palms, and 

 numerous other forms. It is a fact of great interest that 

 the plants of this period occur as fossils in northern lati- 

 tudes all around the world ; and we may be quite certain 

 that there was a continuity of land masses in the vicinity' 

 of the arctic circle at that time. The Sequoias, which are 

 now restricted to California and Oregon, occur as fossils in 

 the Cretaceous strata of Greenland, England, France, Ger- 

 many, Italy, Siberia, Alaska, and Kansas. The northern 

 hemisphere at that time was like a vast botanic garden in 

 which were growing side by side plants which are now dis- 



