I
CR YPTOGAMIA Algae.
Gen. Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
Spec. Char. Crust powdery, pale yellowish green.
Shields sunk in the crust, aggregate, black, with
an elevated black border.
Syn. Lecidea scabrosa. Ach. Meth. 48.
F o u n d by Mr. W . Borrer on tiled roofs in Sussex, and
on flints scattered over the downs of that county, not uncommon.
A considerable affinity, and yet many precise marks of
difference, exist between this and the foregoing-. The crust
of L. scabrosus is thinner, paler, more greenish, and truly
powdery, by no means granulated. The shields are sunk
in its substance so as to be level with its surface, very black,
with a thick border of the same substance and colour. Their
disk is slightly concave, by age sometimes convex. When
the shields happen to be solitary and simple, they are very
small, but they are usually aggregate or compound, and in
that case each group looks like one irregular shield, with a
wavy border, running in concentric lines or plaits over the
disk.
1878
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