With two books like “Our Ferns in Their Haunts” and “How to Know the Ferns” in the field, some might think that the ground is too thoroughly covered to leave room for another, but Dr. Waters has proven otherwise in his new volume with the simple title of “Ferns.”[1] If the older books are taken as books designed for beginners, the new one may be described as one step more technical—a connecting link between popular handbook and scientific manual. In the matter of information it contains practically nothing that has not been published before, being primarily a rearrangement of what is known of our ferns and bearing internal evidence that the pages of the popular works above mentioned have supplied much help in its making. This is especially noticeable in the appropriation of original stanzas from “Our Ferns in Their Haunts,” without giving credit for them. Even when giving credit the author is not always fortunate, as when he ascribes to Miss Pratt certain lines that are Campbell’s. The book is written from the standpoint of the author’s experiences in the vicinity of Baltimore, and as such cannot always be taken as representative of ferns and fern habitats in other parts of our country. The book is also remarkable for the entire absence of author citations for the generic and specific names—in this being unique among American fern books. This will make it difficult for beginners who use this book to look up the species elsewhere. The entire subject of the authority for the names is left untouched in the part that explains why scientific names are used. There is also evident a disinclination to give credit for recent work, the usual statement being that such and such varieties “have been described,” without noting where and by whom. Since these descriptions were heretofore to be found mostly in periodicals, the desirability of mentioning their place of description is apparent. This much being said in criticism of the book, there is yet much to praise. The illustrations are well executed and include a fair proportion of views in the habitats of the ferns, while the photographs of the sori enlarged are exceptionally valuable. Anything like them have never before been published. The analytical key based on the stipes has been well and carefully worked out. It forms a very instructive chapter, though such a key will rarely be consulted by the beginner, because the usual keys are easier. The book is also of interest for the number of varieties or forms included, many of which are not mentioned in the manuals, and for numerous photographs illustrating these forms. There is also a chapter on fern photography. The nomenclature is conservative; old and well known names having been retained in spite of recently proposed substitutes. For his stand in this matter the author is to be greatly commended. The book can in no sense be considered a rival of others in the field. It fills a place of