from their orifices, as in Boletus luridus. In some of the Boleti the color of the flesh is changed on exposure to the air and the tubes often assume the same tints. The tubes, generally called pores, are sometimes closely adherent to the substance of the cap, which is often hard, corky, or coriaceous, as seen in most of the Polyporei.

In the Hydnei, spine-bearing mushrooms, the hymenium is seen covering the spines or needle-like processes which take the place of gills in this order, and which project from the under surface of the cap. These spines may be divided or entire, simple or ramified, and are formed of the substance of the cap. In the early stages of development they appear like small projecting points or papillæ, those on the margin of the cap and at the apex of the stem being always less developed, frequently remaining in this rudimentary state. They are rounded in the species Hydnum imbricatum, sometimes compressed in Hydnum repandum, sometimes terminating in hairs or filaments, as in Hydnum barba Jovis, or very much divided, as in Hydnum fimbriatum.

In the Clavarei, the whole plant consists of solid fleshy masses without any stem of a distinct substance, sometimes club-shaped, sometimes branched with the hymenium smoothly covering the entire surface, never incrusting or coriaceous.

In the Thelephorei, the lower surface of the cap presents neither gills, pores, nor spines, but instead the hymenium covers an uneven or slightly wrinkled surface, partially striate, sometimes obscurely papillose. The plants of this order assume a great variety of shape, from that of a perfect cup with a central stem to an irregularly and much branched frond. They are generally dry and tough. Very few are recommended as edible. Prof. Peck says of this order that probably no edible species will be found in any of its genera outside of the genus Craterellus.

In the order Tremellini we have a great departure from the character of the substance, external appearance, and internal structure of the other orders of the Hymenomycetes. The substance is gelatinous; the form is lobed, folded, or convolute, often resembling the brain of some animal. It is uniformly composed throughout of a colorless mucilage, with no appreciable texture, in which are distributed very fine, diversely branched, and anastomosing filaments. Towards the surface the ultimate branches of this filamentous network give birth to globular cells, both at their summits and laterally, which attain a comparatively large size. These cells are filled with a protoplasm, to which the plant owes its color. The fertile threads are not compacted into a true hymenium.

Representative types of the above-described orders of the Hymenomycetes are shown in Plate B. The various genera, and species of these orders, will be described more in detail in connection with the species illustrated.

CLASSIFICATION.

Owing to the fact that botanists of various countries, writing in diverse languages, have for more than a century been engaged in describing the fungi of their respective countries, with their work frequently unknown to one another, it is not surprising that there has been constant revision, or that many changes have been made in the way of classification and nomenclature which to the amateur student are often confusing.

The classification by the pioneer mycologist, Elias Fries, as presented in his several works on fungi, ignored all microscopical characters, and Saccardo's classification, as presented in his Sylloge Fungorum, was the first complete system offered in its place.

Saccardo, in 1882, commenced his Sylloge, of which not less than twelve volumes have been published. In Saccardo's system of classification the six