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O P E G R A P H A nimbosa.
Clouded Opegrapha.
CRYPTOGAM [A Alga.
Gen. Cha~r. Seeds in black, linear, sessile, simple or
branched,bordered clefts, in an uninterrupted crust.
Spec. Char. Crust leprous, white, shining, rugged,
cracked. Clefts simple, minute, rounded, flattened,
crowded.
Syn. Opegrapha nimbosa. Ach. Meth. 18. t. 1. ƒ. 8.
GrATHERED on the barks of large trees at Coltishall, Norfolk,
by Mr. D. Turner, who .judges it to be what Acharius
intends under the above appellation; nor do we see any reason
for doubt, though, for want of an original specimen, we cannot
be absolutely certain.
This ranks among the smaller species of its genus. The
crust is, as Acharius says, very white, spreading indeterminately,
thin, in some degree polished, rugged, at length
cracked and very uneven. Clefts but little projecting, numerous,
roundish or oblong, curved, obtuse, with a very thin
black edge, and a dilated hoary disk. The figure in Acharius
represents the latter black, as indeed is every part at an early
stage of growth, when the clefts are short and elliptical, almost
round.—The reader will observe a considerable degree of afli-
nity betwixt this and our Lichen lynceus, t. 809, except that
the latter is much larger in all its parts.
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