The English flora - SeaweedAfrica

—
—
Thelotrema.] I.ICHENES. 161
lated olive-brown smooth black-edged, warts of the apothecia
very large and irregular with numerous cells and numerous
black slightly depressed often confluent and then linear curved
points.— Opegrapha crassa, DC.— Stigmatidium crassum, Dabis
in Sot. Gall. v. 2. p. 643. S. obseurum, Spr. (excl. Syn. Pers.)
—Enterographa crassa, Fee.—Lichen obscurus, E. Sot. t. 1752.
(excluding the Syn.)—Porina aggregata, and P. saxicola, Ach.
according to Sprengel.
On the bark of old trees.—This, Sir James E. Smith referred to Arthonia
of Acharius, and supposed it was the A. obscura of that author
while others, Fee and Meyer, have made of it a distinct Genus, the former
under the name of Enterographa, the latter of Stigmatidium, still arranging
it with the Grajohidece. But the real nature of the fructification is
well represented in E. Bot., and Mr. Borrer justly observes that it is
only when the tubercles (or, in allusion to the structure of Pcrtusaria,
the depressed points of the warts) become confluent, that the plant
assumes the appearance of an Arthonia.
8. Thelotrema. Ach. Thelotrema.
Thallus crustaceo-cartilaginous, spreading, adnate, uniform.
Apothecium double, the outer consisting of an open wart formed
of the thallus, the inner (one or two) thin, membranaceous,
breaking away at the top, its disk containing a nucleus.—Named
from ^tjXtj, a wart, and r^/j/xa, a perforation ; an open or perforated
wart.—This Acharian Genus is retained by Mr. Borrer,
and if it were confined to our first and second species, it
would appear to have a structure very unlike that of the other
Lichens, and they may be considered the type of the Genus.
But the other species differ considerably in habit, and assuredly
in their fructification also.
1. T. lepadi/iuui, Ach. (ividc-moutlted Thelotrema); crust
smooth cream-coloured, warts of the apothecia smooth conoid
truncated, inner apothecia (
1 —2) hollow pale-brown with a
thin inflexed edge. Ach. &yn. j>. 1 L5. Schar, Licit, //dr.
j>. (>7. >/. 121. Lichen inchuns, E. Sot. t. 678.
On the bark of trees, not unt'requcnt.
2. T. mclahiiriini. Turn, and Burr. {suKill-nwiitlml T/uIn-
In ma ); crUgtaceOUJ cream-coloured, warts of the apothecia
eo-ivex opening by an irregular inflexed orifice, inner apothecia
depressed brown with a thin obsolete jagged border. Turn.
an, I llorr. in /:'. Btn inn ); crust
Bubtartar i^ thin continuous ash-eolSured, vfartti of ihe apothecia
hemisphtericfe] Witfc a radiated Orifice (their cavity Mink
into the stone ), inner apothecia concave DOSh-l olonred depressed
M
: