PREFACE. 5 
in the world devoted exclusively to ferns. Inits pages | 
now appears the bulk of the periodical literature of ferns. 
Eight volumes have been issued. 
In this book have been included descriptions and 
illustrations of every species known to grow in North 
America north of the Gulf States and east of the Rocky 
Mountains, this area forming a more or less natural floral 
region. With few exceptions they have been treated in 
related groups and arranged as nearly as possible ac- 
cording to season, those first to fruit coming first in the 
book. By means of the illustrated Key to the Genera 
it is believed that no one will have difficulty in ascertain- 
ing the name of any specimen he may find. 
In view of the present unsettled state of botanical 
nomenclature, it has seemed best to adopt, in this volume, 
the botanical names longest in common use. They will 
certainly be less likely to confuse the beginner, since 
they are the names used by a majority of fern students 
and those by which the species are usually mentioned in 
other books. Botanists have recently proposed many 
changes in the interests of a more stable nomenclature, 
but these changes have not been generally accepted. 
Until they have been, they cannot properly be used in a 
volume of this nature. A complete account of these 
changes, however, has been inserted in the text for 
convenience of reference and in addition, a check-list has 
been included at the end of the book, which gives the 
other names by which the various species have been 
known in America. 
The early botanists were mainly engaged in describing 
new species and have left for us the pleasanter task 
of discovering the curious and interesting facts about 
them. In this direction still lies a practically virgin 
