ding to M.
Westendorp,[G] no less than seventy-four species of fungi, and of
these eleven occur on the leaves. The spruce fir, according to the
same authority, nourishes one hundred and fourteen species, and the
oak not less than two hundred.

It is curious to note how fungi are parasitic upon each other in some
instances, as in that of _Hypomyces_, characteristic of the genus, in
which sphaeriaceous fungi make hosts of dead _Lactarii_, &c. We have
already alluded to _Nyctalis_, growing on decayed _Russulae_, to
_Boletus parasiticus_, flourishing on old _Scleroderma_, and to
_Agaricus Loveianus_, on the pileus of _Agaricus nebularis_. To these
we may add _Torrubia ophioglossoides_ and _T. capitata_, which
flourish on decaying _Elaphomyces_, _Stilbum tomentosum_ on old
_Trichia_, _Peziza Clavariarum_ on dead _Clavaria_, and many others,
the mere enumeration of which would scarcely prove interesting. A very
curious little parasite was found by Messrs. Berkeley and Broome, and
named by them _Hypocrea inclusa_, which makes itself a home in the
interior of truffles. Mucors and moulds flourish on dead and decaying
Agarics, and other fleshy forms, in great luxuriance and profusion.
_Mucor ramosus_ is common on _Boletus luridus_, and _Syzygites
megalocarpus_ on Agarics, as well as _Acrostalagmus cinnabarinus_. A
very curious little parasite, _Echinobotryum atrum_, occurs like
minute nodules on the flocci of black moulds. _Bactridium Helvellae_
usurps the fructifying disc of species of _Peziza_. A small
_Sphinctrina_ is found both in Britain and the United States on old
_Polypori_. In _Sphaeria nigerrima_, _Nectria episphaeria_, and two or
three others, we have examples of one sphaeriaceous fungus growing
upon another.

Mr. Phillips has recently indicated the species of fungi found by him
on charcoal beds in Shropshire,[H] but, useful as it is, that only
refers to one locality. A complete list of all the fungi which have
been found growing on charcoal beds, burnt soil, or charred wood,
would be rather extensive. The fungi found in hothouses and stoves are
also numerous, and often of considerable interest from the fact that
they have many of them never been found elsewhere. Those found in
Britain,[I] for instance, are excluded from the British Flora as
doubtful, because, growing upon or with exotic plants, they are deemed
to be of exotic origin, yet in very few cases are they known to be
inhabitants of any foreign country. Som