fluent and flattened, so as to form a more even and rather
thicker crust, which is divided by very narrow cracks into
small irregular areolae, and its hue is browner. Patellulae
somewhat immersed at the base, both margin and disk
mostly rugose, and the former often indistinct. So similar
to this variety is a specimen in the Museum of the Linnean
Society, communicated by Acharius himself as Lecidea
pelidna of his Lichenographia Universalis, the L . lygcea (S of
his Synopsis Lichenum*, that we have hesitated whether
we ought not to regard it as the same, although the warts
of the crust are somewhat larger, the patellulae more convex,
and their margin rarely to be found. In our plant,
however, the patellulae, which have a very slight tinge of
brown when dry, are quite black when moistened; the
reverse of what Acharius remarks of his L . pelidna. A
more minute Lecidea, perhaps the true L . lygcea, occurs
in the same places as our L . prominula «, and sometimes
intermixed with it. It requires further investigation.
The substratum of the thallus is more obscure, and the
warts are more minute and less distinct in L . prominula
than in L . atro-alba, t. 2336. The patellulae, too, are
superficial, not sunk, as in that and several other of the
verrucose Lecidece, in the interstices of the warts. Their
site, number, and uniformly small size, give the plant some
resemblance to Lichen pinicola, t. 1851 f, from which it
differs widely in thallus, as well as in place of growth;
nor indeed are the patellulae so minute as in that .Lichen.
W. B.
* Sheerer, however, in his analytical enumeration of Swiss Lecidea, in
Naturw. Anz. Sckw. No. 2. p. 10. still distinguishes L. pelidna from
L. lygcea.
t Lecidea parasema var. myriocarpa of Acharius in Lich. XJniv. and
Syn. Lich., ^ and probably the vars. punctata and microcarpa. If it be a distinct
species, as we are inclined to believe it, we would still call it pinicola,
as it is confessedly the Lichen pinicola of Acharius in Prod. Lich. Suec.
This author has, in his later works, transferred the name to a slight variety
of Lecanora periclea {Engl. Bot. t. 1850), which he had confounded with
the original Lichen pinicola under Parmelia exigua ji. pinicola in his Meth.
Lich.—Lichen parasemus, Engl. Bot. 1.1450. appears to be what Acharius,
in his Syn. Lich., has distinguished as a species under the name of
Lecidea elccochroma.
2687. (Pig. 2.)
LECIDEA chalybeia.
Metallic-black Lecidea.
CR YP TO GAM I A Lichenes.
Gen. Char. Patellulce sessile or more or less immersed,
with a margin of a substance different
from the thallus.
Spec. Char. Crust thin, leaden-black, glossy ; at
length somewhat tartareous, minutely cracked,
and opake. Patellulae superficial, minute, black ;
disk flat; margins lightly elevated, entire.
T h i s production seems to have been observed only in
Sussex, where it occurs in various places on tiles, and occasionally
on flints : yet it is perhaps not uncommon elsewhere,
since it is likely to be overlooked among Lecanora
exigua, t. 1849, and other minute Lichens, which form in
such situations the first crop of vegetation.
Thallus at first in small round patches, which subsequently
become confluent, and spread indeterminately to a
considerable extent; when young very thin, almost filmy,
continuous, smooth, appearing very minutely verrucose
under a glass, black, or of a very dark lead-colour, shining
with a metallic-like gloss when dry, tinged very faintly with
green when wet; the edges sometimes a little dendritic.
When older, the crust, although still very thin, is slightly
tartareous, and its surface (except generally here and there
in spots) becomes opake, minutely tessellated, and somewhat
rugged, and assumes an obscure brown tint, most
observable when the plant is wet. Patellulae superficial,