CONTENTS 



CHAP. PAGE 



INTRODUCTION 1 



I. THE GEOLOGICAL AGE OF THE FLORAS . . 3 



II. THE TWO DEVONIAN FLORAS 8 



III. RECENT ADVANCES IN OUR KNOWLEDGE OF THE 



MORPHOLOGY AND ANATOINIY OF MEMBERS OF 



THE PSILOPHYTON FLORA .... 14 



IV. A DISCUSSION OF THE NATURE AND AFFINITIES 



OF THE PSILOPHYTON FLORA .... 46 



V. RECENT ADVANCES IN OUR KNOWLEDGE OF THE 



MORPHOLOGY OF THE ARCHAEOPTERIS FLORA 52 



VI. THE PROCORMOPHYTA AND THE ORIGIN OF THE 



CORMOPHYTA (EXTERNAL MORPHOLOGY) . 70 



VII. THE ORIGIN OF THE STELE IN THE EARLIER COR- 

 MOPHYTA 89 



BIBLIOGRAPHY 92 



INDEX 97 



