iv Preface 
in a single species, the account is preceded by a synoptical descrip- 
tion of the fern-plant in its mature stages. 
The distribution of the species is mostly quoted from Mr. 
William R. Maxon’s ‘‘List of the Ferns and Fern Allies of North 
America, North of Mexico, with Principal Synonomy and Dis- 
tribution.”* Most of the spore characters cited are quoted from 
Prof. D. C. Eaton’s “Ferns of North America.” With these 
exceptions, and a few others noted as they occur, all descriptions 
have been drawn from or verified by specimens examined by 
myself. I have personally collected in the field or raised from 
spores nearly all the young leaves figured and described. 
The illustrations of leaves, throughout the book, excepting 
where otherwise stated, are life size. 
The nomenclature is in accordance with the American code. 
Sufficient synonomy is cited to include the more important 
synonyms, 
I wish to render acknowledgments to all who by their cour- 
tesy have aided in any way the preparation of this book. To 
Dr. Lucien M. Underwood I am under obligations for kindly 
examining the synoptical descriptions of the species, for valuable 
suggestions, and for very many kindnesses and courtesies, includ- 
ing the privilege of access to important books and specimens. 
I wish to express likewise my indebtedness to Mr. George E. 
Davenport, for kindness in connection with numerous speci- 
mens. To Dr. Henry F. Walker I am indebted in many ways, 
which it gives me much pleasure to acknowledge. Miss Kath- 
erine Foot also should be especially mentioned. Mrs. N. L. 
Britton and members of the American Fern Society have kindly 
furnished me with certain notes and specimens. 
* Proc. U. S. Nat. Mus. 23: 619-651. rgor. 
