Fungi composed of membranes, fleshy, woody or gelatinous, growing on wood or on the ground. The hymenium or spore-bearing surface exposed at an early stage. The spores are borne on basidia, spread over the surface. The common mushroom is typical of the family. All the members resemble it, more or less, in organization and reproductive organs. These latter, in the mushroom, are spread over lamellæ or gills. The spores, after ripening and dissemination, germinate and produce a mycelium or thread-like vine, which in turn develops the spore-producing part of the plant. Hymenomycetes is divided into the following six Families:— _a._ HYMENIUM FIGURATE. I. Spread over the surface of lamellæ or AGARICACEÆ. gills. II. Lining the interior of tubes or pores. POLYPORACEÆ. III. Clothing the surface of spines or HYDNACEÆ. protuberances of various forms. _b._ HYMENIUM EVEN. IV. Horizontal and mostly on the under THELEPHORACEÆ. surface. V. Vertical and produced all over the CLAVARIACEÆ. surface. VI. Superior, gelatinous fungi. TREMELLACEÆ. FAMILY I.—=AGARICACEÆ.= In the Agaricaceæ the hymenium is spread over lamellæ or gills which radiate from a center or stem. The gills are composed of a double membrane, and are simple or branched. The parts of an Agaric may all be present as in Amanitæ, or severally absent in other genera. When the young fungus is entirely enclosed in a wrapper or case, this case is called the _universal veil_. When this veil is ruptured by the growth of the stem, that part which remains attached to the base is called the _volva_. The membrane reaching from the stem to the margin of the cap is the _partial veil_; when it ruptures by the expansion of the cap and all or a portion adheres to and about the stem it forms the _annulus or ring_. In some species one or both veils may be present, or one or both may be absent. The stem is _central_ when supporting the cap at its center; _excentric_ when at one side of the center; _lateral_ when it supports the cap from the side. If the stem is absent, the cap is said to be _sessile_; if the cap is horizontal and supported by a broad base it is _dimidiate_; if attached to its place of growth by its back it is _resupinate_. Genera are largely distinguished by the manner in which the gills are attached to the stem. These distinguishing attachments are shown in the plates illustrating genera and in Plate IV. Gill-shapes. For convenience Agaricaceæ is divided by the color of the spores into five series: white, pink, brown, purple, black. The last two, owing to the similarity of hue, are by some writers (preferably) included in the black-spored series. Spore color is a valuable assistant in determining species.