LECANORA.] LECA.NO-LECIDEEI. 381 



Hab. On the smooth bark of ash and poplars in maritime and upland 

 districts. Distr. Sparingly in S. and W. England, and among the Central 

 Grampians, Scotland. B. M. : Shanklin, Isle of Wight; New Forest, 

 Hants ; Withiel, Cornwall. Craig Tulloch, Blair Athole, Perthshire. 



Form 2. albiseda Nyl. Lich. Scand. (1861) p. 144. Thallus 

 very thin, white. Apothecia bright-yellow, the thalline margin, 

 thin, white. Cromb. Grevillea, xviii. p. 46. 



A peculiar form, differing in the colours of the thallus, the apothecia, 

 and their thalline margin. 



Hab. On old pales in upland districts. Distr. Only very sparingly 

 in S. England and S.W. Ireland. B. M. : near Lewes," Sussex. Dun- 

 kerron, co. Kerry. 



Var. p. stillicidiorum Nyl. Mem. Soc. Cherb. t. v. (1857) p. 112; 

 Lich. Scand. p. 144. Thallus effuse, very thin, granulose or 

 leprose, greyish-white ; hypothallus obsolete. Apothecia small, 

 yellowish- or olive-green, or dark olive, pruinose, the thalline 

 margin undulate, pale-greyish. Cromb. Lich. Brit. p. 47 ; Leight. 

 Lich. Fl. p. 221, ed. 3, p. 210. Callopisma cerinum j. stillicidiorum 

 Mudd, Man. p. 136. Rinodina stillicidiorum Gray, Nat. Arr. i. 

 p. 456. Lichen stillicidiorum Hornem. Fl. Dan. (1792) t. 1063. 

 f. 2. Lecanora cJiloroleuca Hook. Fl. Scot. ii. p. 48 ; Sm. Eng. Fl. 

 v. p. 190. Lichen cMoroleucus Sm. Eng. Bot. t. 1373. Brit. Exs. : 

 Bohl. n. 94. 



Probably rather a subspecies (cfr. Norrl. Medd. Sa'llsk. pro F. & Fl. 

 Fenn. i. p." 22), differing in the absence of a hypothallus, the colour of 

 the fructification, and in the habitat. The thallus spreads rather exten- 

 sively and the apothecia are numerous, with the thalline margin rarely 

 subpulverulent. 



Hab. Incrusting masses, on calcareous rocks, in upland and subalpine 

 situations. Distr. Local, though not uncommon where it occurs in 

 S.W., Central, and N. England, N. Wales, the S.W. Highlands and among 

 the Grampians, Scotland ; not seen from Ireland. B. M. : Dartmoor, 

 Devonshire ; near Buxton, Derbyshire ; Dolgelly, Merionethshire : Egle- 

 stone, Durham; Cunswick Scar, Westmoreland; nearSkelton, Cumberland. 

 Achrosagan Hill, Appin, Argyleshire ; Craig Tulloch, Perthshire ; Craig 

 Guie and Morrone, Braemar, Aberdeenshire. 



Subsp. 1. L. chlorina Nyl. ex Lamy, Bull. Soc. Bot. t. xxv. 

 (1878) p. 505. Thallus effuse, thickish, granuloso-verruculose or 

 areolato-rimulose, verdigris- or dark-green ; hypothallns not dis- 

 tinct. Apothecia darker cerine. Cromb. Grevillea, xviii. p. 46. 

 Lecanora cerina var. chlorina Leight. Lich. Fl. p. 221, ed. 3, p. 210. 

 Callopisma cerinum ft. chlorinum Mudd, Man. p. 136. Zeora cerina 

 var. chlorina Flot. Lich. Siles. (1849) p. 216. Brit. Exs. : Larb. 

 Lich. Hb. n. 22. 



Distinguished as a subspecies by the more developed thallus, its very 

 different colour, and by the darker apothecia. The hypothallus is con- 

 fused with the thallus. In the few British specimens the apothecia are 



