2728
LECANORA aspersa.
Powdered Warty Lecanora.
CR YPTOGAMIA Lichenes.
Gen. Char. Scutettai sessile, with a margin of the
same substance as the thallus.
Spec. Char. Substratum of the thallus filmy, black;
warts scattered, tartareous, slightly convex, olive-
green, with pale green soredia. Scutellae small,
elevated; margin thick, inflexed; disk black.
F ir s t noticed on loose flints in the neighourhood of
Bury St. Edmund’s, by the Rev. G. R. Leathes. It is
found abundantly near Portslade, and in some other places
on the Downs of Sussex, there also on scattered flints; but
it is not of general occurrence. Both in Suffolk and in
Sussex the scutellae are very rare.
The thallus consists of a black film, beautifully dendritic
at the edges when the surface on which it grows is perfectly
even, and numerous small, roundish, somewhat lobed,
slightly convex warts, unpolished and of an olive-grey hue
when dry, greener when wet, which are usually scattered
separate or in little clusters, more rarely collected into a
tolerably compact crust: their surface marked with minute,,
soredia of pale green powder, changing to a lead-grey in
long-dried specimens. Scutellae minute and inconspicuous,
raised above the surface of the thallus so as to be contracted
at the base; with a thick inflexed margin, of the substance
and colour of the warts, at first entire, afterwards uneven
and somewhat crenate, and a flat dull-black disk.