2726
LECIDEA pulverea.
Pale-green mealy Black-shielded Lecidea.
CR Y I 1 TOG A M I A Lichenes.
Gen. Char, Patellulce sessile or more or less immersed,
with a margin of a substance different
from the thallus.
Spec. Char. Crust indeterminate, soft, mealy, pale
greyish green. Patellulm sessile, largish, black,
internally pale; margin livid, slightly raised, evanescent.
I^ E C E IV E D in 1807, from Charles Lyell, Esq., who
discovered it on oak-bark in the New Forest. Other specimens,
spreading over moss, were communicated to Mr.
Dawson Turner from Ireland, by the late Miss Hutchins.
Thallus composed of minute powdery particles, which
form an irregularly effused, soft crust, of moderate thickness,
pale greyish green or yellowish when living, greyish white
and unchanged by moistening after it has been for some
time dried. No filmy substratum has been observed. Pate11111
® orbicular whilst young, with a slightly elevated,
narrow, somewhat livid or brownish margin, and an unpolished,
black, flat disk, pale brown or whitish within: subsequently
the outline becomes wavy and irregular, and at
length the margin disappears and the disk is found somewhat
convex. The largest patellulae almost equal a hemp-
seed in diameter.
It has been suspected that this Lichen might be a variety
of L . incana, t. 16S3: but Mr. Lyell sent it as distinct, and
Miss Hutchins maintained the same opinion, observing that