CONTENTS. 



LIST OF ILLUSTRATIONS ..... vii 



PREFACE ..... . . . . xi 



THE FERN ALLIES ... i 



KEY TO THE FAMILIES OF FERN ALLIES . . 8 

 THE EQUISETACE^:: SCOURING-RUSHES AND 



HORSETAILS ....... 9 



KEY TO THE SPECIES OF EQUISETUM . . .16 

 THE EVERGREEN EQUISETUMS, OR SCOURING- 



RUSHES ........ 17 



THE DECIDUOUS EQUISETUMS, OR HORSETAILS . 41 

 THE LYCOPODIACE^:, OR CLUB-MOSSES . . .69 

 KEY TO THE LYCOPODIUMS ..... 77 



THE TRAILING LYCOPODIUMS . . . .79 



THE ERECT OR DECUMBENT LYCOPODIUMS . . 105 

 THE PSILOTACE^: . . . . . . . 123 



THE SELAGINELLACE.E, OR DWARF CLUB-MOSSES 129 

 KEY TO THE SELAGINELLAS ..... 135 



THE TRUE SELAGINELLAS, OR SELAGINELLA Ru- 



PESTRIS GROUP ...... 137 



THE CREEPING SELAGINELLA GROUP . . .153 

 THE SALVINIACE.E . ...... 167 



SALVINIA ...... . .. .173 



THE AZOLLAS ........ 179 



THE MARSILIACE/K, OR PEPPERWORTS . . .185 

 KEY TO THE MARSILIAS ..... 191 



THE MARSILIAS ....... 193 



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