The first sub-family includes, first of all, the _Hypogaei_, or
subterranean species. And here again it becomes necessary to remind
the reader that all subterranean fungi are not included in this
order, inasmuch as some, of which the truffle is an example, are
sporidiiferous, developing their sporidia in asci. To these allusion
must hereafter be made. In the _Hypogaei_, the hymenium is permanent and
convoluted, leaving numerous minute irregular cavities, in which the
spores are produced on sporophores. When specimens are very old and
decaying, the interior may become pulverulent or deliquescent. The
structure of subterranean fungi attracted the attention of Messrs.
Tulasne, and led to the production of a splendid monograph on the
subject.[E] Another order belonging to this sub-family is the
_Phalloidei_, in which the volva or peridium is ruptured whilst the
plant is still immature, and the hymenium when mature becomes
deliquescent. Not only are some members of this order most singular in
appearance, but they possess an odour so foetid as to be unapproached in
this property by any other vegetable production.[F] In this order, the
inner stratum of the investing volva is gelatinous. When still young,
and previous to the rupture of the volva, the hymenium presents sinuous
cavities in which the spores are produced on spicules, after the
manner of _Hymenomycetes_.[G] _Nidulariacei_ is a somewhat aberrant
order, presenting a peculiar structure. The peridium consists of two or
three coats, and bursts at the apex, either irregularly or in a
stellate manner, or by the separation of a little lid. Within the
cavity are contained one or more secondary receptacles, which are
either free or attached by elastic threads to the common receptacle.
Ultimately the secondary receptacles are hollow, and spores are
produced in the interior, borne on spicules.[H] The appearance in some
genera as of a little bird's-nest containing eggs has furnished the
name to the order.

The second sub-family contains the coniospermous puff-balls, and
includes two orders, in which the most readily distinguishable
feature is the cellular condition of the entire plant, in its earlier
stages, in the _Trichogastres_, and the gelatinous condition of
the early state of the _Myxogastres_. Both are ultimately resolved
internally into a dusty mass of threads and spores. In the former,
the peridium is either single or double, occasionally borne on a
stem, but usually s