By Dr. J. M. Underwood, Bloomington, Illinois. This little book has the merit of originality of treatment, and explains about ferns in so easy and simple a manner that few will read without knowing more than they did before, and without any great mental effort. It describes all the species of the United States, which at present we may place in round numbers at one hundred and fifty. There is no other work which has all the ferns of the United States described in one volume. A singular error is a chapter on "Morphology of Ferns." It should have been Organography. The morphology of ferns is not touched on in the volume.