PREFACE. 



THE first edition of this manual was published in 1881 and 

 the second in 1882 ; the continued call for copies of the work is 

 the only apology for a new edition. During the past six years 

 the interest in ferns has largely increased, and has resulted not 

 only in a wider and more thorough study of known forms, but 

 in the less explored portion of our territory new species are con- 

 tinually being brought to light. Of the true ferns (forming the 

 order Filices) 140 species were described in the first edition and 

 145 in the second; in the present edition 156 species are re- 

 corded, while three species recognized in former editions have 

 been reduced to varieties. 



The Fern Allies are here augmented by the addition of a 

 genus new to this country (Salvinid), and five species, two of 

 which are here described for the first time ; a reduction of three 

 species has resulted from a more extended study of large suites 

 of specimens, so that 68 species are here recorded. 



While the general plan as developed in the former editions 

 has not been greatly modified, the details of the entire work have 

 been thoroughly revised in order that it may be in harmony 

 with the present aspect of structural and systematic study which 

 every year is adding to the sum of our knowledge. 



The work is intended as an introduction to the study of ferns 

 and a manual for the easy determination of our species ; as such 

 it has aimed to be suggestive in methods of study ; to this end 

 the student is referred to the necessary literature, classified ac- 

 cording to subjects, at the close of each chapter. It is hoped 

 that the introduction of eight pages of references to the intro- 

 ductory literature of plants lower than the pteridophytes may 

 prove valuable to students who, like the writer, have been 

 obliged to grope in the dark with no kindly suggestion as to 

 what works were valuable for beginners. 



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