[ 43* J
L I C H E N b y ffin u s .
Mcaly-bordered Lichen.
C R T P T O G A M I A Alga.
G en. Char. M a le , fcattered warts.
F em a le , fmooth fh ie ld s or tub e r c le s, in. which the
feeds are im b ed d ed .
Spec. Char. Cruftaceous,. p owdery, brownifh. Shields
fla t, d u ll-y e llow , with a- very w h ite , mealy, elevated
border.
S y n . L ich en b y ffin u s. Dick/. Crypt, fafc. 2. in*
With. Bot. Arr. 4r. 3 . 1 7 4 . ed. 3. v. 4.. 2 5 .
X ROFESSOR. HofFmann of Gottingen appears to have originally
defcribed this little Lichen, in his Enumeratio Lichenum, a
work we have not at hand. Mr. Dickfon firft obferved it in
this ifland, growing on trees and ftones in Scotland. Our fpe-
eimen is upon a piece of brick, and was found near London.
The cruft is thin, with a vague indeterminate margin, (lightly
powdery, of a brown more dr lefs dark. Sometimes it acquires
a degree of thicknefs equal to that of coarfe paper,
and then its inner fubftance is whitilh. The Ihields projeft a
little. Their di£fc is very flat, of a dull-yellow or buff-colour
but the white elevated downy margin, which when arrived at
maturity is as it were compofed of two coats or layers,, renders
them very confpicuous.
This has much refemblance at firft fight to the L. marmoreus,
mentioned alfo by Mr. Dickfon in his 2d fafciculus but in
that the cruft is whitilh or afh-coloured when prefent, and fo'
thin and tender that in an advanced ftate of the plant it is not
to be found at all ; its fhields moreover are reddifh, their white
margin thicker and more inflexed, downy rather than mealy*
©f one Ample coat, and crenate.