MESOZOIC AND TERTIARY FLORAS 211 



and twenty-five species, some of which are of very modern appear- 

 ance, s\xch-2iS Zizyphus, Magnolia, Per sea, Acer, Artocarpus, etc. 



Pliocene. — The Pliocene flora of North America is almost a negli- 

 gible quantity, about the only known locality being the Falls of the 

 Columbia River. It includes species in the genera Woodwardia, 

 Sassafras,Sterculia, etc., and is very closely related to living American 

 species. 



Pleistocene. — The Pleistocene flora is better known than the last, 

 yet we are undoubtedly only on the borderland of a knowledge of 

 the plants of this period and their distribution. Small Pleistocene 

 floras are known from New Jersey, Maryland, Virginia, West Virginia, 

 North Carolina, Alabama, New York, Iowa, and Canada. The 

 most extensive exploitation of this flora is that made in Canada in the 

 vicinity of Montreal and Toronto, where Penhallow has been able 

 to make out at least three stages. The species are nearly all living. 



