CRYPTOGAMIA Algae.
Gen. Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
Spec. Char. Crust circular, white, chalky, cracked,
crenate. Shields depressed, black; their margin
whitish stained with grey.
Syn. Lichen rimosus. Ach. Prod. 62. Retz. FI.
Scand. ed. 2 . 2 7 5. Dicks. Crypt, fasc. 1 . 1 2 .
With. v. 4. 25. Hull. 292. .
L. FI. Dan. t. 468. ƒ 3.
Parmelia glaucoma (3 . Ach. Meth. 161.
O u r specimens of this Lichen were collected by the Rev.
J. Holme, F.L. S., on the top of Heartside Fell between Penrith
and Alston, Cumberland, where it is very conspicuous on
the blue limestone rocks. We have also received it from the
* Rev. FI. Davies, and have seen it in various places, always on
calcareous stones.
Its crust is generally circular, of a very white chalky appearance,
somewhat elevated in the centre, though not thick ;
the surface full of angular cracks, though less so than many
others; and the extreme e'dge crenate. The shields are numerous
in the central part, not near the edge, irregularly disposed,
depressed, scarcely projecting above the level of the crust;
their disk flat, opaque, black, having a glaucous-grey tinge
when young; their border apparently of the substance of the
disk rather than of the crust, yet it is whitish, being only
stained, as it were, with grey, which colour is often extended
to the crust immediately surrounding each shield.
We are always loth to dissent from Dr. Acharius, whose
deep knowledge'and candid love of truth render his authority
of the greatest weight, but we must consider this Lichen as
distinct from his glaucoma (the varians of Mr. Davies, Tr. of
L . Soc.v. 2 . t. 28), nor are we certain that they belong to the
same genus in his system.
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