it, but is usually enveloped by the thallus, which frequently
spreads over their whole surface. Now and then they are
bare, black, and polished. They have often a rugged and
imperfect appearance. As in V. epidermidis, and in various
other species, the orifice varies from a regular pore to a minute
chink, and broken tubercles occasionally form a white
spot surrounded by a narrow black ring.
We adopt the present genus, under a character intended
to include the Acharian genera Verrucaria, Endocarpon, and
Pyrenula. Some of its species are given in our former volumes,
at t. 533,593, 594, 595,1499,1500, 1512,1681,1698,
1711, 1712, 1752, 1776, 1848,1891, 2012, 2013, 2412,2455,
2456, 2539, 2540, 2541, 2580 : and perhaps those at t. 677,
and 2372, Acharian Porince, might be referred to it.
2597. (Fig. 2.)
V E R R U C A R I A rhyponta.
Black Stain Verrucaria.
S p e c . C h a r . Crust roundish, filmy, continuous, rough-
ish as if minutely flocculose, black. Tubercles
very minute, prominent, hemispherical, black, for
the most part slightly rugose.
S yn . Verrucaria rhyponta. Ach. Lich. Univ. 282.
Syn. 89.
I t is not wonderful that a production so obscure as the
present should have been but little noticed. It was first
observed in Britain by Mr. Lyell, in the New Forest,
and it has since been found in the forests of Sussex, on
the trunks of young trees. It grows parasitically on the
Graphis scripta of Acharius*; or rather, to all appearance,
it is formed beneath the crust of that plant, and gradually
bursts through and destroys it in little stain-like spots. The
thallus is of a dull black, sometimes slightly tinged with
grey or olive. It appears roughish under a glass, as if minutely
granulated, or, more properly, flocculose or fibrous.
Somewhat of a metallic-like lustre is here and there observable.
This might, in our English specimens, be attributed
to the crust of the Lichen on which they occur; but it is
found also on a specimen from Acharius, which is seated
unaccompanied on the bark. The tubercles, so minute as
to be scarcely discoverable by the naked eye, are usually of
the same hue as the thallus, and roughish, as if encrusted
by i t : occasionally they are polished, and more perfectly
black. They are orbicular, moderately convex; their apex
is sometimes slightly papillose, sometimes umbilicate; their
orifice extremely minute, often hardly to be detected; their
nucleus whitish.
The less spreading thallus, and the much more minute
tubercles, seem to distinguish this little plant from V. oliva-
cea. Yet Mr. Lyell has found, on beech bark, in the New
Forest, a dark olive-crusted Verrucaria, nearly intermediate
in both these respects. We refer it rather to V. olivacea
than to V. rhyponta: future observation may perhaps prove
it distinct from both.—W. B.
* Syn. p . 81. where G. pulverulenta and G. Cerasi stand as varieties of
it. Perhaps G. serpentina ought to be united to the same species. Our
Opegrapha scripta, t. 1813, is very different, and scarcely distinct from
O. Lyellii, 1.1876.