PERXrSARlA.] LECANO-LKCIDEEI. 499 



Hah. On rocks, praiiitic and schistose, in maritime and mountainous 

 districts.— Z>/.s7r. K'athor local in Great Britain, Ireland, and the Channel 

 Islands. — B. .M. : Chateau Point, Island of Sark. Aberdovey and Cwm 

 Bychan, Merionethshire ; Island of Anjjlesea. Near Moffat, Dumfries- 

 shire ; West Water, Forfarshire ; Ben Lawers and Craig Calliach, Perth- 

 shire ; Portlethen, Kincardineshire j Glen Ey, Braemar, Aberdeenshire. 

 Blackwater, co. Kerry. 



h. Spores normally 2nae. 



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

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

 areolate, the verructe subglobose, difForm, greyish or glaucous-white 



(^torlngt''''^'^*^^-)- Apolhecial or several, usually 2 in each 

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

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

 or 3i]De), 0,130-160 mm. long, 0,04.5-05 mm. thick. — Leight. Lich. 

 Fl. p. 23S, ed. 3, p. 221) ; Angio. Lich. p. 27, t. 9. f. 3 ; Cromb. 

 Lich. Brit. p. h% \ Mudd, Man. p. 275; !Sm. Eng. Fl. v. p. KJO ; 

 Turn. & Borr. Lich. Br. p. 196. — Porina i)erlam Hook. Fl. Scot. ii. 

 p. 45 ; Gray, Xat. Arr. i. p. 495. Lichen jjcrtasu.s 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 i-uc/os'tm, 

 cinereum, (/lahrmn Dill. Muse. 128, t. 18. f. 9 pro parte. — According 

 to the specimens in his Herb, this is Lichen 2i^itusus 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 bv a pale, 

 zonate, narrow, rarely broad, hypothalline hue, aud is but moderately 

 thick even when best developed. It is almost always very well fertile, 

 the verrucfe being numerous, often crowded, and then more or less couHueut 

 aud difEorm 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 ofteu without spores. The ostioles are occasionally whitish, an 

 " immature " state called leucostoma by Schaerer (Enum. p. 229), owino- 

 probably to the plant growing in shade, when the epithecium gives no 

 reaction with K. 



Hah. On the trunks of old trees, rarely un 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 Glenh am, Suffolk ; Epping Forest, Essex ; Shiere, 

 Surrey ; Penshurst, Kent ; St. Leonard's Forest aud near Hastings, 

 Sussex ; Appuldurcombe, Isle of Wight ; Xew Forest, Hants ; Ulla- 

 combe, near Bovey Tracey, and Lustleigh, S. Devon ; Withiel, Cornwall ; 

 Cirencester, Gloucestershire ; GopsaU Park, Leicestershire ; Millersdale, 

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

 nethshire ; Hafod, Cardiganshire ; Bettws-y-Coed, Denbighshire ; Island 

 of Anglesea ; Church Stretton and Llauforda, Shropshire ; Kildale and 

 near Ayton, Cleveland, Yorkshire ; Teesdale, Durham ; Windermere, 

 Westmoreland; Calder Abbey, Cumberland. New Galloway, Kirkcud- 

 brightshire ; Roslin aud Coliuton "Woods, Midlothian ; near Glasgow ; 



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