pearance, and do not cease till we reach an altitude of 18,000
feet.
In respect of genera, they are in general diffused almost
indiscrimmately over the surface of the globe. A few genera
only are peculiar to warm climates, and some of these have
their representatives on either side of the basin of the Mediterranean.
The same species occur sometimes at great distances
from each other, being confined to small districts in
each locality. Java, the Sikkim Himalayas, New Zealand,
and South Carolina, produce a curious plant,* allied to Geäster,
which occurs on decayed laurels, without any intermediate
stations, and other instances might be brought forward. The
species which occur in different tropical countries often differ
widely, especially the Polypori, hut it is certain that there are
hundreds of undescribed species to reward future researches,
and till the genus has been more closely studied, it is difficult
as yet to come to any accurate conclusions.
As regards cosmopolite species, it is curious that the common
Mushroom is one of the most universally diffused, but
it may he doubted whether this has not accompanied the introduction
of the horse, consequent on the dispersion of the
human race.
But little has at present been made public respecting the
distribution of species in Europe. Fries is, however, collecting
materials for the solution of this difficult question. The
great evil is, that so few persons have made such a critical
study of the more important species which retain their characters
but imperfectly when dried, that it is not always
possible to give implicit credit to lists of species which may
be published in local Floras. Indeed, some notion of the
difficulty may be found from the frequent alterations of sy-
* Triclioscytale paradoxa.
nonyms which appear in the works even of the best Eungo-
logists. Much remains also to be done in the south of Europe,
notwithstanding the labours of such trustworthy authorities
as Vittadini, and till the Southern Fungi are worked out
in the same spirit an'd with the same accuracy with which
he has attacked a portion of the Fungi of Italy, it will be
impossible to ascertain correctly the limits of species.
I t is requisite, however, not only to study their limits in
latitude, hut the geological limits also. These will probably
prove far more striking. The predominance of Truffles in
limestone formations above other strata is a well-know’ii fact,
and there is little doubt that a comparison of lists belonging
to different formations would give equally striking results in
other groups. The subject is well worth attention, and will
be found highly interesting to those who have facilities of
visiting different districts for comparison. I t must be remembered,
in considering this subject, that species cannot
become permanent inhabitants of any district if extremes
exist destructive to their spawn. Excessive drought, or moisture,
extreme heat or cold at certain times of the year, may
prevent the establishment of a species, especially where that
species is a long time before it sends np perfect fruit from
its spawn. I t is probable that few ever make their appearance
which are not able to exist permanently. The Vine Mildew
and Potato Mould are at present examples in favour of
this notion, but it is to be hoped that, under some peculiar
concurrence of circumstances fatal to their growth, they also
may at length entirely disappear.
But little can be said of the occurrence of Fungi in earlier
periods of the earth, before the introduction of man into the
universe. No certain traces of Eungi are to be met with till
very recent periods, though a few anomalous productions have