PERTCSAK1A.] 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. 



6. Spores normally 2nae. 



13. P. communis DC. Fl. Fr. ii. (1805) p. 230. ThaUus deter- 

 minate, membranaceo-cartilaginous, smoothish, rugose or verrucoso- 

 areolate, the verrucae subglobose, difform, greyish or glaucous-white 

 ( K +oran7e iSh ' CaC1 ~)- Apothecia 1 or several, usually 2 in each 

 verruca ; the ostiola minute, punctiform (or slightly depressed), black 

 or blackish (epithecium K-f- violet) ; spores 2na3 (occasionally solitary 

 or 3nae), 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. ii. 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 proparte. 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. Exs. : 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 verrucse 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 (Enurn. 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, S. Devon ; Withiel, Cornwall ; 

 Cirencester, Gloucestershire ; Gopsall Park, Leicestershire ; Millersdale, 

 Derbyshire ; Malvern, Worcestershire ; Dolgelly and Barmouth, Merio- 

 neths'hire ; 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, Kirkcud- 

 bri"-htshire ; Roslin and Colinton Woods, Midlothian ; near Glasgow ; 



2x2 



