PA XX ARIA.] LECANO-LECIDEEI. 339 



convex and often with the thalline margin obliterated (form btatoroidea 

 Cronib. Grevillea, xviii. p. 42). 



Hob. On earth-covered walls and hedge-banks, rarely on decaying 

 stumps, in maritime and upland districts. Distr. Rather local, though 

 plentiful where it occurs in the Channel Islands, here and there through- 

 out England ; scarce in N. Wales, Scotland, and S. Ireland. B. M. : 

 Quenvais and St. Brelade's Bay, Island of Jersey; Islands of Sark, 

 Guernsey, and Alderney. North Wootton, Norfolk; Epping Forest, 

 Essex ; near Bovey Tracey, S. Devon ; St. Germains, Penzance, and 

 Withiel, Cornwall ; near Malvern, Worcestershire ; Hay Forest, Here- 

 fordshire ; Barmouth, Merionethshire ; Bangor, Carnarvonshire ; Egle- 

 stone, Durham ; near Ennerdale Lake, Cumberland. New Galloway, 

 Kirkcudbrightshire ; Airds, Appin, Argyleshire ; Loch Tay and Killin, 

 Perthshire. Co. Cork. 



4. P. Hookeri Xyl. Mem. Soc. Chcrb. v. (1857) p. 109 ; Syn. ii. 

 p. 32. Thallus radioso-crustaceous, appressed, greyish or greyish- 

 brown, granuloso-corrugate in the centre, radiately lineato-plicate 

 or only lobulato-effigurate at the circumference ; hypothallus thin, 

 black. Apothecia nearly moderate, plane, black or blackish, in- 

 ternally pale, the thalline margin usually crenulate ; spores ellipsoid, 

 0,014-15 mm. long, about 0,009 mm. thick ; hymenial gelatine 

 bluish, then sordid-red with iodine. Mudd, Man. p. 125 ; Cromb. 

 Grevillea, xviii. p. 43. Lecanora Hookeri Hook. Fl. Scot. ii. p. 51. 

 Lichen Hookeri Eng. Bot. xxxii. (L811) t. 2283. Pannaria leuco- 

 lepi* Cromb. Lich. Brit. p. 42 ; Leight. Lich. Fl. p. 165, ed. 3, p. 151. 

 Squamaria leucolepis Sm. Eng. Fl. v. p. 194. Brit. Exs. : Leight. 

 n. 267. 



An interesting species well characterized by the colours of the thallus 

 and apothecia,, as also by the nature of its habitat. The thallus when 

 perfect is orbicular, placodioid, sometimes leaden-greyish, with the hypo- 

 thallus little visible and at length evanescent. It is usually well fertile, 

 with numerous, crowded apothecia, which in old plants are entirely black. 



Hab. On rnicaceo-schistose rocks in alpine places. Distr. Very local 

 and rather scarce on the summits of a few of the S. Grampians, Scotland ; 

 reported also by Leighton, but very doubtfully, from N.W. Ireland (Con- 

 nemara, co. Galway). B. M. : Ben Lawers, Mael Graedha and Craig 



Calliach, Perthshire. 



Yar. /3. leucolepis Nyl. Syn. ii. (1870) p. 33. Thallus squamu- 

 lose, greyish-white or lurid-greyish ; squamules subimbricate, sub- 

 creuate, sometimes slightly striate towards the circumference. 

 Apothecia black, the thalline margin subentire or at length subcre- 

 nate; spores about 0,015-19 mm. long, 0,008-10 mm. thick. 

 Cromb. Grevillea, xviii. p. 43. 



Usually confounded with the type by British and other authors, but 

 distinguished by the less developed thallus and by the size of the spores. 

 The apothecia also are fewer, with the thalline margin less crenulate. 



Hab. On decaying mosses upon rocks in alpine situations. Distr. Ex- 

 tremely local and scarce on the summit of one of the S. Grampians, Scot- 

 land. B. M. : Ben Lawers, Perthshire. 



