e species found in such
localities are not confined to them, as _Agaricus coepestipes_,
_Agaricus cristatus_, _AEthalium vaporarium_, &c. It is somewhat
singular that certain species have a predilection for growing in
proximity with other plants with which they do not appear to have any
more intimate relation. Truffles, for instance, in association with
oaks, _Peziza lanuginosa_ under cedar-trees, _Hydnangium carneum_
about the roots of _Eucalypti_, and numerous species of _Agaricini_,
which are only found under trees of a particular kind. As might be
anticipated, there is no more fertile habitat for fungi than the dung
of animals, and yet the kinds found in such locations belong to but a
few groups. Amongst the _Discomycetes_, a limited number of the genus
_Peziza_ are fimicolous, but the allied genus _Ascobolus_, and its own
immediate allies, include amongst its species a large majority that
are found on dung. If we take the number of species at sixty-four,
there are only seven or eight which do not occur on dung, whilst
fifty-six are fimicolous. The species of _Sphaeria_ which are found on
the same substances are also closely allied, and some Continental
authors have grouped them under the two proposed genera _Sporormia_
and _Sordaria_, whilst Fuckel[J] proposes a distinct group of
_Sphaeriacei_, under the name of _Fimicoli_, in which he includes as
genera _Coprolepa_, _Hypocopra_, _Delitschia_, _Sporormia_,
_Pleophragmia_, _Malinvernia_, _Sordaria_, and _Cercophora_. The two
species of _Pilobolus_, and some of _Mucor_, are also found on dung,
_Isaria felina_ on that of cats, _Stilbum fimetarium_ and a few other
moulds, and amongst Agarics some species of _Coprinus_. Animal
substances are not, as a rule, prolific in the production of fungi.
_Ascobolus saccharinus_ and one or two others have been found upon old
leather. _Onygena_ of two or three species occurs on old horn, hoofs,
&c. Cheese, milk, &c., afford a few forms, but the largest number
infest dead insects, either under the mouldy form of _Isaria_ or the
more perfect condition of _Torrubia_, and occasionally under other
forms.

Robin[K] has recorded that three species of _Brachinus_, of the order
Coleoptera, have been found infected, whilst living, with a minute
yellow fungus which he calls _Laboulbenia Rougeti_, and the same
species has been noted on other beetles. _Torrubia Melolonthae_[L] has
been described by Tulasne as occurring on the maybug or cockchaf