70 On the Lichen-Flora of Epping Forest,
s. n. V. umbrina). On flints about High Beach. Rather
sparingly (J. M. C). Probably also elsewhere.
V. viridula, Schrad. — On brick walls, Hoe Street, Wal-
thamstow (Hb. E. F.). Formerly on mortar of a wall at
Epping Town (J. M. C).
From the above list it will be perceived that the number of
lichens which have been collected in the Forest during the
present century amounts to 171 species, varieties, and forms.
Having been carefully examined both by Mr. Forster and
myself, it may be assumed that only a very few things, if any,
have remained unnoticed, and that we can scarcely expect
any further additions to be made to the catalogue. This,
compared with that of many smaller woodland tracts, seems
rather meagre, and scarcely sufficient to repay the investiga-
tions of any but a purely local lichenist. At the same time,
as we shall see, this very scantiness is suggestive of various
important points connected with the conditions of lichen life
and development, which apparently are but little understood
by botanists in general. Suffice it at present to observe that,
although the Forest extends over a very considerable area,
even though no longer coterminous with that of Hainault,
now destroyed,3 yet from its inland situation and general low
altitude, the nature of the gravelly and clayey soil, the absence
of any large streams or lakes, the manner of growth of the
prevailing species of trees, it could not be expected to yield a
very rich harvest to the collector. From the remarks made
on their distribution in the enumeration given, it is evident
that many of the species and varieties formerly gathered are
to be expunged from the present lichen-flora of the Forest.
This may be estimated at about eighty-five species and
varieties, so that there is a decrease of rather more than one-
half of the total number collected. As will be gathered also
from the said list, the decrease during the interval when
Forster ceased collecting and my original visits to the Forest
3 Although but a very few species from a single locality in Hainault.
Forest are present in Forster's herbarium, there are good grounds for
believing that it was richer in lichens than Epping Forest strictly so-
called.