Squamaria- tsidwvdes.
2808
PARMELIA isidioides.
Isidium-like Parmelia.
CRYPTO0 AM IA Lichenes.
Gen. Char. Scutellae formed from the thallus, affixed
by a central point, the circumference free.
Disk of a different substance from the margin.
Spec. Char. Thallus of minute greenish-grey scales,
white when dry, with branched cylindrical segments.
Mai’gin of scutellae thick, rugged ; disk
purplish black.
A n exquisitely beautiful little Lichen, of which we
know nothing except from the communications of the Rev.
T. Salwey, who found it, in 1835, “ upon one tree in an open
grove inCwm Bychan, about two miles above Llanbedr, near
Barmouth.” The only doubt that has occurred is whether
it may not possibly be an extraordinary state of Parmelia
Clementi, t. 1779. The resemblance of the apothecia to
those of that Lichen and of P. erosa, t. 2807, require it to be
referred to the same genus. Mr. Salwey suggested the
very appropriate trivial name.
Thallus scattered over mosses, and appearing to the naked
eye a mere greyish-white mealiness, greenish when wet,
among which the scutellae are barely perceptible. A glass
of considerable power shows it to consist of minute scales,
branching out into, or formed by the confluence of, little
cylindrical or slightly compressed segments, perfectly resembling
the podetia of an Tsidium or young Sphcero-
phoron, varying in position from decumbent to ascending
and erect, some nearly simple, others more or less copiously