_Phallus_.]

PODAXINEI.--This is a small but very curious group of fungi, in which
the peridium resembles a volva, which is more or less confluent with
the surface of the pileus. They assume hymenomycetal forms, some of
them looking like Agarics, Boleti, or species of _Hydnum_, with
deformed gills, pores, or spines; in _Montagnites_, in fact, the gill
structure is very distinct. The spores are borne in definite clusters
on short pedicels in such of the genera as have been examined.[S]

HYPOGAEI.--These are subterranean puff-balls, in which sometimes a
distinct peridium is present; but in most cases it consists entirely
of an external series of cells, continuous with the internal
structure, and cannot be correctly estimated as a peridium. The
hymenium is sinuous and convolute, bearing basidia with sterigmata and
spores in the cavities. Sometimes the cavities are traversed by
threads, as in the _Myxogastres_. The spores are in many instances
beautifully echinulate, sometimes globose, at others elongated, and
produced in such numbers as to lead to the belief that their
development is successive on the spicules. When fully matured, the
peridia are filled with a dusty mass of spores, so that it is scarcely
possible in this condition to gain any notion of the structure. This
is, indeed, the case with nearly all _Gasteromycetes_. The hypogaeous
fungi are curiously connected with _Phalloidei_ by the genus
_Hysterangium_.

[Illustration: FIG. 9.--Basidia and spores of _Lycoperdon_.]

TRICHOGASTRES.[T]--In their early stages the species contained in
this group are not gelatinous, as in the _Myxogastres_, but are
rather fleshy and firm. Very little has been added to our knowledge
of structure in this group since 1839 and 1842, when one of us
wrote to the following effect:--If a young plant of _Lycoperdon
coelatum_ or _L. gemmatum_ be cut through and examined with a common
pocket lens, it will be found to consist of a fleshy mass,
perforated in every direction with minute elongated, reticulated,
anastomosing, labyrinthiform cavities. The resemblance of these to the
tubes of _Boleti_ in an early stage of growth, first led me to
suspect that there must be some very close connection between them.
If a very thin slice now be taken, while the mass is yet firm, and
before there is the slightest indication of a change of colour, the
outer stratum of the walls of these cavities is found to consist of
pellucid obtuse cells, placed par