orders of the Hymenomycetes are not essentially different in their arrangement from that of Fries, although Saccardo has raised all the subgenera of Agaricus to the rank of genera, and then altered their sequence so as to bring them into four sections, distinguished by the color of their spores. Having raised the old subgenera of Fries to generic rank, Saccardo found it necessary to limit the application of the term Agaricus to the group of fungi to which it was originally applied by Linnæus, viz., the common field mushroom Agaricus campester, and its allies, represented by Agaricus arvensis, Agaricus Rodmani, etc., or, as Prof. Peck more definitely states it, "to those of the gilled mushrooms which have brown spores, free gills, a stem bearing a ring, gills generally pink-colored in the early stage, and brownish black when fully matured." M. C. Cooke, the distinguished English mycologist, prefers to retain the genus Agaricus with its original subgenera intact, succeeded by the other genera of Agaricini, as in the Hymenomycetes Europei of Fries, giving as his reason the belief "that for purposes of classification features should be taken which are present and evident in the specimens themselves, and are not dependent on any of their life-history which cannot be presented in the herbarium."

In a work such as the present, which is designed to be popular in character rather than purely technical, it is deemed advisable to select as a basis for classification that system which is most accessible to reference by the general reading public. Saccardo's Sylloge, while exhaustive in character and of inestimable value to the mycologist, is written in Latin, and is, moreover, a very expensive work—facts which render it practically unavailable to the general public.

In the compilation of this series of pamphlets I have adopted the classification of M. C. Cooke, which, as regards the Hymenomycetes, the family containing most of the fleshy fungi, is, with exceptions noted, in accord with that of Saccardo. M. C. Cooke's hand-book of fungi is of convenient size and form for ready reference.

For the convenience, however, of those who may wish to familiarize themselves with both systems, a synopsis of Saccardo's Genera of Hymenomycetes will be given later.

STRUCTURAL CHARACTERISTICS OF THE AGARICINI.

By far the greater number of the Agaricini have both cap and stem. The form of the cap, as well as that of the stem, varies somewhat in the different genera and species. Those which are terrestrial in habit are generally of an umbrella-like shape, while those which grow upon trees and decayed tree-stumps are apt to be one-sided or semi-spherical.

In many of the parasitical mushrooms the stem is absent. Where the stem is present it is either an interrupted continuation of the hymenophore or fleshy substance of the cap, or else is supported separately as a pillar on which the cap rests, a more or less distinct line of demarcation showing where the fibers terminate. Sometimes it is quite easily detached from the cap socket, as in the Lepiota procerus. It may be hollow or stuffed, solid or fibrillose. It varies in length and thickness. In some species it is smooth and polished, in others rough and hairy, reticulated, etc., sometimes tapering, sometimes distinctly bulbous at the base.

The spores of the species differ in color and are usually globular or oblong in shape. All of these characteristics assist in determining the species.

MUSHROOM GILLS.

Mushroom gills, or lamellæ, anatomically considered, are composed, first, of a central portion, a prolongation of the hymenophore or flesh of the cap, more or less dense, sometimes so thin as to be scarcely perceptible; second, the hymenium or spore-bearing membrane covering the surfaces of this