viii ■ CONTENTS. 



Protophytes— AlgsE Proper- Gradual Diiferentiation of Vegetal ive 

 and Reproductive Parts— Evolution of new Groups— Distribution 

 — Fossil Algce /■ ^S 



CHAPTER IV. 



LICHENES. 



General Characteristics — Development of Mutualism or Commensalism 

 ^The Schwendenerian View of tlie Nature of Lichens — Views of 

 Opponents of Schwendener's Ideas — Probable Origin of Mutualism 

 — Do Lichens constitute a Terminal Group ?— Fossil Lichens /. 190 



CHAPTER V. 



CHARACE^. 



General Characters — Affinities — Habitat— Fossil Species ... /. 194 



CHAPTER VI. 



MUSCINE^. 



Transition from Thallophytes to Cormogens — Alternation of Generations 

 — Differentiation of Tissues — Epidermis and Stomata — Bilateral 

 Structure — Appearance of an erect Stem bearing Leaves— Spore 

 Structure and Ornamentation — Habitats — Fossil Forms ... p. 199 



CHAPTER VII. 



PTERIDOPHYTA. 



General Characteristics — Appearance of Fibro-vascular Bundles — 

 Trae Roots — Epidermis and Stomata — Decadence of the Sexual 

 Generation or Oophore — Prothallus — Microspores and Megaspores 

 — Modes of Branching — Fossil Forms /. 208 



CHAPTER VIII. 



PHANEROGAMIA. 

 Gymnospermese — Angiospermeae p, 229 



