with a film, the greater part of their surface. The exposed
portion is black and polished, sometimes mammillated,sometimes
dimpled, and often marked with a distinctly perceptible
pore.
Specimens, apparently of this species,'fou nd by Mr.Robert-
son, by the Tyne, near Newcastle, on sand-stones exposed
to the tide, are variously tumid, and of a darker and more
olive hue than usual. These have much of the general
appearance of some states of the Endocarpon viridulum of
Schrader, the species to which the Lichen tessellatus, badly
described and figured in Engl. Bot. 533, belongs. The
L . viridulus, t. 2455, we now believe unpublished elsewhere,
and we propose to call it V. elceina. The two species may
be thus distinguished :
V. elceina. Crust thin, tartareous, cracked, smooth,
slightly tumid above the tubercles, greenish olive.
Tubercles small, immersed, black, between hemispherical
and conical; at length emerging.
S y n . Lichen viridulus. Engl. Bot. v. 35. 2455, excluding
the synonyms.
V. viridula. Crust of polygonal granulato-crenate scales,
thickish, tartareous, rugose, greenish olive-brown.
Tubercles largish, black, partially immersed, conical.
To this common and very variable species belong the
synonyms quoted in Engl. Bot. 2455. Acharius, in his
Lickenographia Universalis, p. 290, gave the plant of Schrader
as a variety of V.fuscella, {One Lichen fuscellus of Turner
and of Engl. Bot. 1500,) but corrected this error in the
addenda to that work, p. 675, where V. viridula stands as
a species, distinguished both from V. fuscella and from
V. tessellata. In his Synopsis Lichenum, p. 126, he has properly
united it with the latter as a species of his genus
Pyrenula, but has retained the trivial name tessellata, given
in English Botany to the young state of the plant, in preference
to that previously bestowed on the species by Schrader.
The crust of this species is originally frustulose ; that of
V. elceina originally continuous; so that the two belong to
different sections of the genus. W. B.