PANNARIA.j LKCAXO-LECIDKIir. 339 



convex and often with tlie tlialline margin obliterated (form ln(it'n-oid>-a 

 Cromb. tirevillea, xviii. p. 4-"}). 



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

 stumps, in maritime and upland di.stricts. — I)i4r. Ilather local, though 

 plentiful where it occurs in tlie Channel Islands, here and there thrnugh- 

 out En^'land ; 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. Ciermains, 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. Cberb. 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 : hypothaUus thin, 

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

 ternally pale, the thaUine 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, sviii. p. 43. — Lecanora Hool-eri Hook. Fl. Scot. ii. p. 51. 

 Lichen Hooheri Eng. Bot. xxxii. (ISll) t. 2283. Pannaria leuco- 

 lepis Cromb. Lich. Brit. p. 42 ; Leight. Lick. Fl. p. 165, ed. 3, p. 151. 

 Squamana lencole_pis 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- 

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

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



Hab. On micaceo-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, fromN.W. Ireland (Con- 

 nemara, co. Galway). — B. M. : B^en Lawers', Mael Graedha and Craig 

 Calliach, Perthshire. 



Var. /3. leiicolepis Xyl. 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 0,01-5-19 mm. long, 0,008-10 mm. thick. — 

 Cromb. Grevillea, xviii. p. 4-3. 



Usually confoimded 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. 



Hah. 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. 



z2 



