/ e; / [ 1849 ]
LICHEN exiguus.
Diminutive Black-shielded Lichen*
CRYPT0GAM1A Algce.
Gen. Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
Spec. Char. Crust orbicular, radiating, thin, leprous, uneven,
dull ash-coloured. Shields minute, clustered,
flat, black, at length rather convex j their margin
white, at length brownish.
Syn. Lichen exiguus. Ach. Prod. 69.
Parmelia exigua. Ach. Meth. 154.
W e have at t. 17§1 expressed some do^ubts about the L. exiguus
of Acharius, which arose from his specimens; but
Mr. W. Borrer having lately sent us from Sussex what appears
by comparison the true plant, we shall give all the information
in our power concerning it. Mr. Turner finds the
same on old pales about Yarmouth.
On old tiles the crust is seen in most perfection, forming
small circular patches, very thin, of a dull brownish ash-
colour, leprous and uneven, not tartareous, encircled with a
fibrous radiating margin unnoticed by Acharius. Shields
minute, numerous, crowded, black, flat when young, with
a very distinct smooth whitish border. By age the border
becomes brown, but we cannot observe that it disappears.
The disk grows convex when old.
From the most mature examination of original specimens, it
appears evident to us that L. pyrinus of Acharius is this very
plant, and by no means a variety of sophodes, and further,
that L. alietinus of Ehrhart is the pericleus, t. 1850. The
figure in the Stockholm Transactions for 1795, t. 5. ƒ. 6,
d, e, f, seems rather sophodes, t. 1791 , which is intermixed
with Dr. Acharius’s own specimens of exiguus, and perhaps
led him to cite that figure under it.
FUa.iiSoB, TubtUhA T>y Jo.i Joira'by, London,.