PERTUSARIA. | LECANO-LECIDEEI. 499 
Hab. On rocks, granitic and schistose, in maritime and mountainous 
districts.— Distr. Rather local in Great Britain, Ireland, and the Channel 
Islands.—B. M. : Chateau Point, Island of Sark. Aberdovey and Cwm 
Bychan, Merionethshire ; Island of Anglesea. Near Moffat, Dumfries- 
shire; West Water, Forfarshire ; Ben Lawers and Craig Calliach, Perth- 
shire; Portlethen, Kincardineshire; Glen Ey, Braemar, Aberdeenshire. 
Blackwater, co. Kerry. 
b. Spores normally 2ne. 
13. P. communis DC. Fl. Fr. ii. (1805) p. 230.—Thallus deter- 
minate, membranaceo-cartilaginous, smoothish, rugose or verrucoso- 
areolate, the verruce subglobose, difform, greyish or glaucous-white 
(K cheats CaCl—). Apothecia 1 or several, usually 2 in each 
verruca; the ostiola minute, punctiform (or slightly depressed), black 
or blackish (epithecium K+ violet); spores 2nz (occasionally solitary 
or 3nz), 0,130-160 mm. long, 0,045-65 mm. thick.—Leight. Lich. 
FL p. 238, ed. 3, p. 229; Angio. Lich. p. 27, t. 9. f. 3; Cromb. 
Lich. Brit. p. 58; Mudd, Man. p. 275; Sm. Eng. Fl. v. p. 160; 
Turn. & Borr. Lich. Br. p. 196.—Porina pertusa Hook. Fl. Scot. ii. 
p. 45; Gray, Nat. Arr. i. p. 495, Lichen pertusus Linn., Huds, 
Fl. Angl. ed. 2, p.525; Lightf. Fl. Scot. i. p. 802; With. Arr. ed. 3, 
iv. p. 15; Eng. Bot. t. 677. Lichenoides verrucosum et rugosum, 
cinereum, glabrum Dill. Muse, 128, t. 18. f. 9 pro parte.—According 
to the specimens in his Herb. this is Lichen pertusus Linn. Mant. 
ii. (1771) p. 134, but his specific name is not adopted as it has 
fallen into desuetude.— Brit. Hxs.: Mudd, n. 264. 
The most common and widely distributed (at least in a fertile state) of 
the British Pertusarias. The thallus is orbicular, limited by a pale, 
zonate, narrow, rarely broad, hypothalline line, and is but moderately 
thick even when best developed. It is almost always very well fertile, 
the verrucze being numerous, often crowded, and then more or less confluent 
and difform by mutual pressure. The apothecia, as observed by Turner 
and Borrer, vary from one to twelve in each verruca; while in old plants 
they are often without spores. The ostioles are occasionally whitish, an 
“immature” state called leucostoma by Schaerer (Enum. p. 229), owing 
probably to the plant growing in shade, when the epithecium gives no 
reaction with K. 
Hab. On the trunks of old trees, rarely on pales, in maritime, lowland 
and upland tracts.—Distr. General and abundant in Great Britain; no 
doubt also in Ireland and the Channel Islands.—B. M.: Islands of Sark 
and Guernsey. Great Glenham, Suffolk; Epping Forest, Essex; Shiere, 
Surrey; Penshurst, Kent; St. Leonard’s Forest and near Hastings, 
Sussex ; Appuldurcombe, Isle of Wight; New Forest, Hants; Ulla- 
combe, near Bovey Tracey, and Lustleigh, 8. Devon; Withiel, Cornwall ; 
Cirencester, Gloucestershire ; Gopsall Park, Leicestershire; Millersdale, 
Derbyshire ; Malvern, Worcestershire ; Dolgelly and Barmouth, Merio- 
nethshire; Hafod, Cardiganshire ; Bettws-y-Coed, Denbighshire; Island 
of Anglesea ; Church Stretton and Llanforda, Shropshire; Kildale and 
near Ayton, Cleveland, Yorkshire; Teesdale, Durham; Windermere, 
Westmoreland; Calder Abbey, Cumberland. New Galloway, Kirkeud- 
brightshire ; Roslin and Colinton Woods, Midlothian Pate Glasgow ; 
K 
