CRYPTOGAMIA Algae.
G en. Char. Seeds in black, linear, sessile, simple or
branched, bordered clefts, in an uninterrupted crust.
Spec. Char. Crust irregularly circumscribed, very
thin, smooth, glaucous-white. Clefts very minute,
short, oblong or roundish, turgid, simple or somewhat
aggregate.
Syn. Opegrapha epipasta. Ach. Meth. 26.
Lichen epipastus. Ach. Prod. 23.
C o m m o n on the smooth barks of trees. We have it from
Thorpe near Norwich, from Yarmouth, and from Sussex.
The crust forms roundish patches, well determined but not
regularly circular, smooth, thin, of a greyish or glaucous
white. By age it often grows more white and flaky. Fructification
sprinkled over the crust like little black dots, rising
up under its flakes, and so acquiring a sort of broken spurious
border. Each dot, or cleft, is short, and, generally speaking,
rather roundish than linear, tumid, rugged ; very rarely aggregate
so as to seem branched or compound. The habit of
the crust, and of the fructification when microscopically examined,
prove this to be a real Opegrapha, however dissimilar
at first sight from other species, and confirm the genus as a
natural one.