/<s J [ 2336 ]
CRYPTOGAMIA Algce.
Gen. Char. M ale, scattered warts.
Female/smooth shields or tubercles, in which the
seeds are imbedded.
Spec. Char. Crust indeterminate, very thin, continued,
black, with grey, roughish, convex, crowded
warts. Shields in the interstices, coal-black,
flattish, at length convex, with an elevated black
border.
Syn. Lichen atro-albus. Linn. Sp. PL 1607. Ach.
Prod. 63. Wulfen in Jacq. Coll.v. 2 . 1 8 5 .1.14. f . 1.
Lecidea atro-alba. Ach. Meth. 45,
CxREAT difficulties have attended the determination of some
of the Linnaean crustaceous Lichens, from the brevity of their
characters and the want of authentic specimens for comparison.
It would be endless to particularize, and often impossible to ascertain,
what has been intended under the present appellation by
various writers. We must content ourselves with the authority
of Acharius and Swartz, and we have no better, to fix this
as the atro-albus of Linnaeus, with whose short account it
agrees; and we exhibit at fig. 2 their identical specimen. At
fig. I is a native one, received from the north of England by
Mr. Turner, which we presume sets the question for ever at
rest as to our Flora. We gladly do Wulfen the justice to observe
that he is one of the few botanists who have rightly determined
this difficult species, though he did notfindtheshields.
Under our L. verruculosus, t. 2317, we have adverted to
atro-albus. The crust of the latter, though likewise black,
thin, and inseparable from the stone, is more continued and
less fibrous. The copious warts it bears are crowded, convex,
grey or brownish, roughish with a sort of powder that may be
rubbed off. Shields sessile between the warts, not upon them,
coal-black, flattish when young, with a thick, entire, nearly
even border of the same hue and substance; when old, the disk
becomes convex, the border more inconspicuous. This plant
gives some idea of L. cceruleo-nigricans, t, 1139, in miniature.
1 .