The English flora - SeaweedAfrica

148 LICHENES. [Verrucaria.
yet, well marked as it appears to be, Mr. Borrer observes that there are
varieties most puzzlingly intermediate between it and O. Lyellii.
16. O. venosa, Pers. (veiny Opegrapha); crust tartareous determinate
reddish-white, apothecia immersed convex without any
proper border repeatedly branched curved parallel and equidis-
tant obtuse at the ends, surrounded by a slightly elevated accessory
border formed of the crust. Pers. in Annul der Wetterav.
v. 2. p. 15. t. 10./. 2. E. Bot. t. 2454.
On the trunks of Beech in the New Forest, Hampshire, and almost
always surrounded by Pertusaria crassa, C. Lyell, Esq.— Sir Jas. E. Smith
well describes " the lirellce as curiously and regularly disposed, much
branched, twisted; but their ramifications, however complex and varied,
keep generally at equal distances from each other, like the walls of an
artificial maze. They are deep sunk in the crust, but convex above, in-
tensely black with obtuse terminations; not tapering to a point, as in O.
dendritica, nor do they, as in that, spread radiating from a centre." Mr.
Borrer, in a letter, doubts the correctness of the reference to Persoon
but although it must be confessed that his short description is very unsatisfactory,
the figure seems to be sufficiently characteristic. The same
acute observer has already, in E. Bot. Suppl., under Arthonia impolita (/.
2692), remarked that " Meyer has perhaps done well in placing O. dendritica
and O. Lyellii in a new Genus, his Platygramme, to which our
O. venosa also must belong. They appear to differ from Opegrapha by
wanting a proper border to the apothecia and they can scarcely be
placed in Arthonia:' Most of the species referred to Platygramme by
Sprengel are exotic, natives of China. Our own 3 species appear to
prefer the warmer parts of Europe, and in Britain they inhabit the
southern districts only.
Obs. The Opegrapha macularis of Ach. and O. epiphaga of Ach. and E.
Bot., are altogether to be excluded from the Lichens, as species of Hysterium.(Borr.)
M. Fee, however, still ranks them among the Lichens, and
in the present family, forming of them a Genus which he calls Hcterographa.
b. Apothecia hemispherical (tubercula), enclosing a nucleus.
Fam. IV. Verrucarieje.
5. Verrucaria. Pers. Verrucaria.
Thallus crustaceous or cartilagineo-membranaceous, spread-
ing-, adnate, uniform. Apothecia (tubercula) hemisphaerical or
subglobose, innate and immersed or sessile, corneous, of a different
colour and substance from the thallus, (mostly a black
crust or shell) enclosing a nucleus, the apex papillary, often at
length perforated, sometimes covered by the wart-like processes
of the thallus, (when it constitutes the Pyrenula, Ach.)—Name:
verruca, a wart, from the wart-like processes on the thallus.
—The characters of this genus are not satisfactorily defined.
Pyrenula, separated from it by Acharius, is, by almost general
: