BRITISH LICHENS

306 PYRENOCARPElE VERRl1CARIA
immersion: in that case V. hYu'1"ela would rank as a variety or growth
form of the previously described plant. b
Hab. On rocks and stones usually in streams.-Distr. In upland
districts, rare in N. England, the Grampians, Scotland, and S. and
W. Ireland.-B. lIJ. River Ithon, Llandrindod, Radnorshire; Airy.
holme Wood, Cleveland, Yorkshire; Ben Lawers, Perthshire; Cork;
Blackwater Bridge, Killarney, Kerry.
14. V. degenerascens Nyl. ex Larb. Lich. Hb. n. 200, nomen.­
Thallus dark-brown, moderately thick, subdeterminate, mucilaginous
when moist, continuous, then irregularly cracked, not
distinctly areolate. Perithecia minute, semi-immersed, slightly
depressed round the prominent ostiole; perithecial wall black,
entire, thick above, continued beneath the base by a thinner
layer; spores somewhat oblong, narrower at one end, 17- rarely
20 flo long, 5-7 flo thick.
Exsicc. Larb. Lich. Hb. n. 200.
Differing from the two preceding species in the drier habitat, in
the smooth superficially cracked thallus and in the smaller spores.
[Jab. On rocks.-B. M. Ben-y-Gloe, Perthshlre; Island on Lough
Feagh, Connemara, Galway.
15. V. margacea Wahlenb. Fl. Lapp. 465 (1812).-Thallus
olive- or greyish-brown, thin, smooth, somewhat shining, continuous,
effuse or determinate. Perithecia moderate in size,
immersed in the thallus, becoming emergent, opening by a pore,
the perithecial wall dimidiate, or thinly developed under the base;
,spores ellipsoid or oblong, rather large, 24-35 flo long, 10-16 flo
thICk or rather larger; hymenial gelatine wine-red with iodine.­
Cromb. Lich. Brit. III (excl. vars.); Leight. Lich. Fl. 416;
ed. 3, 446 (excl. vars.). V. subme1·sa Borr. in Sm. Engl. Bot.
Suppl. t. 2768 (1833). V. Letghtonii Hepp Flecht. Eur. n. 95
(1853); Mudd Man. 287 pro parte. Thelotrema margacea Wahlenb.
ex Ach. Meth. Suppl. 30 (1803).
On moist rocks often about the margins of streams.-Disl1". Rather
rare throughout the British Isles.-B. ]1,1. Trefriw Falls, Bettws.y.
Coed, Carnarvonshire; Dan HIll and Staveley, Westmorland; Craig
Tulloch, Blair Athole and Ben Lawers, Perthshlre; Morrone, Braemar,
Aberdeenshire; near Balllllhasslg, Cork; Caher Mt., Kerry.
16. V. latebrosa Kmrb. Syst. Lich. Germ. 349 (1855).­
Thallus reddish-grey, effuse, thin, faintly areolate. Pcrithecia
moderate in size, somewhat shining black, sessile more or less
covered at the base by the thallus; perithecial wall dlmidiate;
spores usually 8 in the ascus, large, ellipsoid, becoming slightly
brownish, 30-35 flo long, 12-15 flo thick.-Leight. Lich. Fl. cd. 3,
448.
Exsicc. Larb. Lich. Hb. n. 237.
Nearly allied to the preceding but with a less gelatinous thallus
and more emergent perithecia.