LE CI DE A aeruginosa.
Dark-green powdery Lecidea.
CR YPTOGAMIA Lickenes.
Gen. Char. Patellulae sessile or more or less immersed,
with a margin of a substance different
from the thallus.
Spec. Char. Crust indeterminate, granulöse, greenish
gray, at length covered with aeruginose
powder. Patellulae superficial, small, dull-black,
brownish, or reddish; disk flat; margin elevated,
somewhat flexuose.
C o m m o n in Sussex on decaying rails, but rarely producing
patellulae.
The thallus forms irregular and often wide patches, and
consists of an obscure cyanescent film, with numerous granulations,
so small as to be hardly distinguishable by the naked
eye, arising from it, and more or less uniformly covering it.
These are of irregular figure, at first smooth, of a pale,
dull, grayish green when wet, and gray when dry, but soon
burst, and pour forth abundance of very minute, dark verdigris
green, powdery particles, which form, together with
the granules from which they proceed, a very uneven crust
of inconsiderable thickness, white within, except a variable
superficial layer of green. In barren specimens this powder
is not unfrequently collected into roundish clusters, looking
not unlike the fructification of a Variolaria or Spiloma.
The patellulae are generally numerous when they occur at
all, are scattered, superficial, about the size of poppy-seed,
unpolished, black, with a brownish or sometimes greenish
tinge when dry, varying when wet from black to reddish