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L I C H E N subfuscus.
Brown-shielded Crustaceous Lichen.
CRYPTOGAMIA Algee.
G en. Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
Spec. Char. Crust thin, continued, smoothish, brownish-
white. Shields sessile, slightly convex, reddish-
brown, with a tumid, whitish, entire border.
Syn. Lichen subfuscus. Linn. Sp. PI. 1609. Ach.
Prod. 47. Huds. 529. With. v. 4. 2 1 . Hull. 290.
Relh. 451. Sibth. 323. Abbot. 262.
Lichenoides crustaceum et leprosum, scutellis sub-
fuscis. Dill, in Raii Syn. 71. Muse. 134. t. 18.
/ . 16.
Parmelia subfusca. Ach. Meth. 167.
V e r y common on the smooth barks of trees. The crust
forms roundish patches, of various sizes, and is uninterrupted,
usually very thin, though calcareous, minutely granulated,
but not leprous nor powdery, of a slightly brownish or greyish
white. On dead wood it sometimes by age becomes tumid
and broken, and on walls now and then of a considerable
chalky substance, but is never so thick nor so white as the
crust of ater, t. 949. This wall variety was given us by
Mr. Turner, see fig. b, but is not that meant by Dillenius,
which is epipolius. See Tr. of L. Soc. w. 7- 111- 1
The shields are abundant, often crowded, their disk rather
convex, usually of a bay or chesnut colour, but varying in
brightness, often parti-coloured, or mixed with a pale waxy
hue, as if the impregnation of the seeds had failed there, and
the disk had withered or dropped out. The border is of the
substance and colour of the crust, or rather whiter, entire,
or slightly crenate, especially when old. In a variety sent by
Mr. Lyell, from beeches in the New Forest, the crust is
greenish, the disks of the shields darkish hrown, very tumid,
and in a manner proliferous or compound, see fig. c.
a
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