CRYPTOGAMIA Algae.
Gen. Char. Seeds in black, linear, sessile, simple or
branched, bordered clefts, in an uninterrupted crust.
Spec. Char. Crust expanded, smoothish, membranous,
white. Clefts immersed, powdery, zigzag, branched
and confluent, with an elevated border from the
crust.
Syn. Opegrapha pulverulenta. Persoon in Ust. Ann.
fa sc .-l. 29. i. 1 . / . 2 , B, b. Ach. Meth. 28.
L. scriptus, var. Ach. Prod. 25. Hoffm.'Enum. t. 3.
f . 2, a, b. <
N o t uncommon upon trees. We are obliged to Mr. Turner
for well-authenticated specimens, not having ourselves received
this species from Professor Acharius, or at least only
its large variety £.
The crust is of the same colour with that of 0 . denigrata,
t. 1 753, but more spreading and undefined, thicker and more
uneven, rising up into a Spurious border to the fructification.
The clefts are deeply immersed, zigzag, more or less branched,
divaricated and confluent, pointed at the extremities; their
disk powdery and whitish, which is the origin of the specific
name.
Most probably tab. 18.ƒ. 1. of Dillenius might be drawn
from a specimen of this species; but we have not received any
information upon the subject, nor have we visited his herbarium
at Oxford since the subject of this genus came under
our consideration.
JiaicijAo-/. jft&Zufc&lQ' Jet f So>verby Zondarrv.