rmediate kind of cushion or stroma. The two
families in which an hymenium is present are called _Hymenomycetes_
and _Gasteromycetes_. In the former, the hymenium is exposed; in the
latter, it is at first enclosed. We must examine each of these
separately.

The common mushroom may be accepted, by way of illustration, as a type
of the family _Hymenomycetes_, in which the hymenium is exposed, and
is, in fact, the most noticeable feature in the family from which its
name is derived. The pileus or cap bears on its under surface
radiating plates or gills, consisting of the hymenium, over which are
thickly scattered the basidia, each surmounted by four spicules, and
on each spicule a spore. When mature, these spores fall freely upon
the ground beneath, imparting to it the general colour of the spores.
But it must be observed that the hymenium takes the form of
gill-plates in only one order of _Hymenomycetes_, namely, the
_Agaricini_; and here, as in _Cantharellus_, the hymenium is sometimes
spread over prominent veins rather than gills. Still further
divergence is manifest in the _Polyporei_, in which order the hymenium
lines the inner surface of pores or tubes, which are normally on the
under side of the pileus. Both these orders include an immense number
of species, the former more or less fleshy, the latter more or less
tough and leathery. There are still other forms and orders in this
family, as the _Hydnei_, in which the hymenium clothes the surface of
prickles or spines, and the _Auricularini_, in which the hymenium is
entirely or almost even. In the two remaining orders, there is a
still further divergence from the mushroom form. In the one called
_Clavariei_, the entire fungus is either simply cylindrical or
club-shaped, or it is very much branched and ramified. Whatever form
the fungus assumes, the hymenium covers the whole exposed surface. In
the _Tremellini_, a peculiar structure prevails, which at first seems
to agree but little with the preceding. The whole plant is gelatinous
when fresh, lobed and convolute, often brain-like, and varying in
size, according to species, from that of a pin's head to that of a
man's head. Threads and sporophores are imbedded in the gelatinous
substance,[C] so that the fertile threads are in reality not compacted
into a true hymenium. With this introduction we may state that the
technical characters of the family are thus expressed:--

_Hymenium free, mostly naked, or, if enclosed a