OPEGRAPHA venosa.
Veiny Opegrapha.
CRYPTOGAMIA Algce.
Gen. Char. Seeds in black, linear, sessile, simple or
branched, bordered clefts, in an uninterrupted crust.
S p e c . C h a r . Crust tartareous, determined, reddish
white. Clefts immersed, convex, without any
elevated border, repeatedly branched, curved, parallel
and equidistant, obtuse at the ends.
DISCOVERED by Charles Lyell, Esq. growing upon the trunks
of Beeches in Hampshire, but rarely. It is remarkable for being
always surrounded by Lichen discurus, 1. 1752, now reckoned
an Arthonia; see v. 29. 2079.
Nothing can be more curious or distinct than the present species,
when duly examined. The crust is limited, and perhaps
black-edged j but this it is hard to determine, on account of the
surrounding plant, which has certainly a black border. Its substance
is tartareous, rugged and uneven, white with a dirty reddish
tint, scarcely powdery. The clefts are curiously and regularly
dispersed, much branched and twisted, but their ramifications,
however complex and varied, keep generally at equal distances
from each other, like the walks of an artificial maze.
They are deeply sunk in the crust, but convex above, intensely
black, with obtuse terminations; not tapering to a point, as in
0 . dendritica, 1.1756, nor do they, as in that, spread radiating
from a centre.
Mr. Lyell at first sent this Opegrapha under the apt name of
elahorata; but appears to have since determined it to be the
venosa of Persoon, of which however we find no mention in any
book that has yet come to our hands. Perhaps it may be included
in the Lichenographia Universalis of Acharius.