CRYPTOGAMIA Algce.
G en. Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
S pec. Char. Crust spreading, cracked, mealy and very
white. Shields somewhat sunk, small, crowded,
g re y ; at length black, convex, with a very black
border.
S yn. Lichen corticola. Ach. Prod. 57.
L. albo-ater. Ehrh. Crypt. 176.
L. amylaceus. ibid. 303.
Lecidea corticola. Ach. Meth. 53. Winch Guide, 35.
Verrucaria albo-atra. Hoffm. P l.L ich . v. 1 . 76. t. 15.
ĥ 2 .' _ _ _ _ _
X FIRST observed this species on some old trees in Mr. Kett’s
grounds at Seething, Norfolk. Mr. Sowerby has received
specimens from Mr. James Turner, Mr. W. Borrer and the
late Mr. Brunton. 9
It always grows, as the name implies, upon bark, and that
of old rugged oaks more especially. The chief difficulty
lies in distinguishing it from L. epipolius, t. 1137, which
grows on old walls, and whose crust is more tartareous and
grey. The crust of the present plant is white, thin and mealy,
sometimes indeed rugged or tumid, but not so tartareous. The
shields are partly sunk in the crust, flattish when young, and
clothed with a blue mealiness, except their border which is
always blackish. In time the disk grows convex, and both
that and the border are intensely black, by which last character
the species is certainly known. We have compared
authentic specimens, of this and the epipolius, with numerous
ones of British growth.
Ju n e.u 3 o 8 .T iib tish '& b y J a f Sow erby JonK orv.