BRITISH LICHENS

360 PYRENOCARPElE ARTHOPYRENIA
Often confused with A. microspila, owing to the dark-coloured
thallus which in both occurs in rather small patches.
Hab. On bark of trees.-Distr. Very rare throughout the British
Isles.-B. 111. Curland near Taunton, Somerset; St. Leonard's Forest,
Sussex; Airyholm, Cleveland, Yorkshire; Killin, Perthshire.
30. A. Cerasi Massal. Ric. Lich. 167 (1852).-Thallus greyish
or brownish, thin, morc or less shining, subdeterminate. Pedthecia
very small, more or less elliptical, numerous, black, shining;
perithecial wall dimidiate; paraphyses breaking up, entangled
upwards, often becoming almost obsolete; spores colourless,
elongate-oblong, generally rather narrow, blunt at the ends,
3-septate, 15-25 11. long, 4-8 11. thick.-Verrucaria Cerasi Aeh.
Meth. 119 (1803); Leight. Lich. Fl. 441; ed. 3, 471.
Distinguished by the shining thallus and the elliptical perithecia,
a character that is sometimes rather obscure. The spores in the
Somerset specimen are for a long time I-septate.
Hab. On the bark of cherry and other trees.-Distr. Rare in S.
and S.W. England.-B. ]}I. Castle Neroche, near Taunton, Somerset;
Hurstpierpoint, Sussex.
31. A. grisea Koerb. Syst. Lich. Germ. 369 (1855).-Thallus
effuse, thin, yellowish- or reddish-brown, rather shining. Perithccia
scattered, minute ('35 mm. diam.), hemispherical, immersed,
. the small poriform ostiole emerging; perithecial wall dimidiate;
asci obovoid-cylindrical, about 55 11. long, 17-20 f1. wide; paraphyses
few, stoutish, entangled; spores 8 in the ascus, oblong-clavate,
1- then 3-septate, round at the ends, almost breaking up into
halves, 20-22 11. long or rather longer, 5-6 11. thick.-A. Crombiei
A. L. Sm. in Journ. Bot. xlix. 43 (19] 1) & Monogr. Lich. ii. 328
(1911); Verrucaria epidermidis var. grisea Schleich. ex Schrer.
Spicil. 56 (1826).
Differs from A. submicans in the form of the spores and the presence
of paraphyses. Owmg to a misunderstandmg of the spores of
Verrucaria grisea, the above was described as a new species, A.
Crombiei.
Hab. On bark of trceS (alder).-B. M. Banks of the Garry, Blair
Athole, Perthshire.
32. A. submicans Arn. in Verh. KK Zool.-Bot. Ges. xxiii.
530 (1873).-Thallus yellowish or paie-reddish-brown, thin,
effuse. Perithecia numerous, small, hemispherical, shining, black,
the ostiole minutely poriform; perithecial wall dimidiate; paraphyses
very' scanty or none; asci obclavate, rather short; spores
8 in the ascus, linear-oblong or slightly clavate, 4-guttulate, 1then
3-septate, colourless, sometimes becoming brownish, 16-2511.
long, 4-6 11. thick.-Verrucaria submicans Nyl. in Flora Iv. 363
(1872); emend. Leight. Lich. Fl. ed. 3, 471 (1879).
The spores originally described by Nylander as 2-celled only,