2657
L E C I D E A rufescens.
Reddish sunk-shielded Lecidea.
CRYPTOGAMIA Lichenes.
Gen. Char. Patellulce sessile or more or less immersed,
with a margin of a different substance
from the thallus.
Spec. Char. Crust indeterminate, thin, tartareous,
tessellated, brown. Patellulae small, dark ches-
nut, immersed; at length flat with an elevated
entire margin.
Svn. Sagedia rufescens. Ach. Lich. Univ. 329.
Sj/n. 135.
A DISTINCT and apparently very rare Lichen. Indeed
we have no knowledge of its having been observed
elsewhere than at Gorlestone, Suffolk, whence specimens
growing, like ours, on sandstone, were communicated to
Acharius. Wliat appears to be a variety, with a less considerable
crust and more prominent patellulae, occurs near
the same place on flints.
The crust forms irregular patches, composed of small,
flattish, angular, crowded frustula, various in size and
figure, thin, but tartareous; their surface smooth, unpolished,
and of a reddish brown varying in intensity, their
internal substance whitish. Patellulae numerous, often
several in one areola of the crust; immersed at first, gradually
expanding and disclosing a concave, at length flat,
disk, of a darker and redder brown than the crust, almost
black when dry, encircled by a rounded, entire, slightly
raised margin of the same or a rather paler hue, with
which the crust also is tinged for a little space around.
When separate, their outline is usually circular, but they
often crowd each other and become confluent, and not un