488 LICHENACEi. [LECA.NORA. 



ii. p. 125. Biatorella pruinosa Mudd, Man. p. 191, t. 3. fig. 74. 

 Lichen pruinosus 8m. Eng. Hot. xxxii. (1811) t. 2244. Brit. Exs. : 

 Leight. n. 300 ; Mudd, n. 160. 



It is only occasionally that a tballus varying from whitish to dark 

 greyish is distinctly visible, so that the plant is often described as ecrus- 

 taceous. Were it not for the character of the spermogones it might 

 readily be taken for a polyspored Lecidea. A state occasionally occurs on 

 chalk pebbles in which the apothecia are much smaller and subimmersed 

 as if calcivorous (var. immersa, Fr. Lich. Eur. p. 296). 



Hab. On calcareous rocks and mortar of walls from maritime to upland 

 tracts. Distr. General and common in Great Britain : probably also in 

 Ireland. B. M. : Shiere, Surrey; Lewes, Sussex; Shanklin, Isle of 

 AVight ; near Penzance, Cornwall ; Cirencester, Gloucestershire ; near 

 Hereford ; near Malvern and AVhittington, Worcestershire ; Harboro' 

 Magna, Warwickshire ; near Corwen, Merioneth ; Bilsdale, Cleveland, 

 Yorkshire ; near Gainford, Durham ; Leven's Park, Westmoreland. 

 Appin, Argyleshire ; King's Park, Stirling ; Craig Tulloch, Blair Athole, 

 Perthshire ; near Aberdeen. Dunkathal, co. Cork. 



Form nnda Nyl. ex Laray, Bull. Soc. Bot. t. xxv. (1878) p. 423. 

 Thallus little visible or entirely wanting. Apothecia small or 

 moderate, reddish- brown, epruinose, Cromb. Grevillea, xix. p. 58. 



Differs merely in the constantly naked apothecia, which probably 

 depends on habitat. 



Hah. On rocks, chiefly calcareous, rarely arenaceous, and mortar of 

 walls in upland situations. Distr. Only here and there in Great Britain ; 

 but no doubt often overlooked. B. M. : Egerton, Kent ; near Bovey 

 Tracey, S. Devon ; Cirencester, Gloucestershire ; Malvern, Worcestershire. 

 Appin, Argyleshire ; Ben Lawers and Craig Tulloch, Blair Athole, Perth- 

 shire ; Applecross, Ross-shire. 



Yar. /3. albocincta Cromb. Thallus obsolete. Apothecia thinly 

 pruinose or naked, with a white pruinose epithalline margin ; other- 

 wise as in the type. 



Looks entirely lecanorine and as if the type of the species, but has no 

 gonidia intruded in the spurious margin, which becomes evanesceut in 

 age. It is probably the plant referred to by Th. M. Fries in Lich. Scand. 

 p. 407, s. n. Lecidea immersa var. . atrosanyuinea Sornm. Suppl. Fl. Lapp, 

 p. 152 ; but as the latter I. c. says that the margin is " black," I have 

 named it as above. The apothecia in the two British specimens seen are 

 here and there congregate when the epithalline margin is flexuose. 



Hab. On the mortar of a wall in an upland district. Distr. Extremely 

 local and scarce in W. England. B. M. : Mathou, Malvern Hills, Wor- 

 cestershire. 



194. L. encarpa Nyl. Not. Sallsk. pro F. et Fl. Fenn. Forh. xi. 

 (1871) p. 184. Thallus absent or scarcely any visible. Apothecia 

 large, lecideine, often aggregate, at first concave then plane, black, 

 dark-reddish when moist, reddish within, the margin black, persistent; 

 hypothecium thin, blackish-brown ; spores oblongo-ellipsoid, 0,004- 

 5 mm. long, about 0,002 mm. thick ; hymenial gelatine deep-bluish 

 with iodine. Cromb. Grevillea, xix. p. 58. Lecanora glaucocarpa 



