2642. (Pig- 1.)
V E R R U C A R I A aphanes.
Inconspicuous Verrucaria.
CRYPTOGAMIA Lichenes.
Gen. Char. Tubercles of a different substance from
the thallus, simple, convex, not expanding, but
furnished with a central pore, and inclosing a
somewhat gelatinous nucleus.
Spec. Char. Crust indeterminate, very thin, continuous,
minutely rugose, olive. Tubercles very
minute, nearly globose, covered with a pale
olive powder.
T h i s is probably not an unfrequent production on old
elms, but being visible to the naked eye only by a dull dark
olive tinge, it may well be passed over as the naked surface
of the bark. Our specimens grew at Henfield, Sussex, and
near Yarmouth.
The crust is found, when examined with a magnifier, to
be a film as thin as possible, spreading indeterminately,very
minutely wrinkled, unpolished, continuous, frequently disappearing
in spots : its colour a brownish olive when dry,
and becoming greener upon the application of moisture.
Tubercles most minute, numerous, yet dispersed rather
distantly over the crust, and very rarely any of them
crowded together; they are either more or less deeply
sunk, or variously prominent, sometimes so much so as to
show a contraction at the base ; their surface is regularly
convex, either apparently naked and of an unpolished black
with a tinge of brown, or, much more commonly, covered,
as if powdered, with a pruina,' which is of a paler tinge
than the crust, occasionally greyish and approaching to
white. This does not however, in general, conceal the orifice,
which appears a little round black or brownish dot,
occasionally, but not frequently, dilated into an irregular