CONTENTS. 



CHAPTER I. 



PAGE 



Preliminary Ideas of Geological Chronology and of the Classi- 

 fication of Plants . . . . . . . . 1 



CHAPTER II. 



Vegetation of the Laurentian and Early Paleozoic — Questions 



as to Algje . .8 



CHAPTER III. 



The Erian or Devonian Forests — Origin of Petroleum— The 



Age of Acrogens and Gymnosperms . . . . .45 



CHAPTER IV. 



The Carboniferous Flora —Culmination of the Acrogens — For- 

 mation of Coal 110 



CHAPTER V. 



The Flora of the Early Mesozoic — Reign of Pines and Cycads . 175 

 CHAPTER VI. 



The Reign of Angiosperms in the Later Cretaceous and Early 



Tertiary or Kainozoic 191 



2 



