388 LICHEN ACEI. [LECANORA. 



Hob. On calcareous rocks, rarely on flints in maritime and mountainous 

 districts. Distr. Rather local, though common where it occurs in Great 

 Britain ; not seen from Ireland. B. M. : Reigate, Surrey ; Lydd Beach, 

 Kent ; Peasemarsh and near Lewes, Sussex ; Isle of AVight ; Cunning 

 Dale, Buxton, Derbyshire ; Island of Anglesea ; Craig-y-Rhiw, Oswestry, 

 Shropshire ; Eglestone, Durham ; Leven's Park, Westmoreland ; Bywell, 

 Northumberland. King's Park, Edinburgh ; Achrosagan Hill, Appin, 

 and near Ben Cruachan, Argyleshire ; Craig Tulloch, Blair Athole, Perth- 

 shire; Craig Guie and Morrone, Braemar, Aberdeenshire. 



Form incrustans Cromb. Grevillea, xviii. (1889) p. 46. Thallus 

 very thin, white, usually evanescent. Apothecia minute, immersed, 

 plane or slightly convex, thinly margined. Lecanora rupestris 

 forma incrustans Leight. Lich. Fl. p. 191, ed. 3, p. 203. Lecidea 

 rupestris fi. incrustans Mudd, Man. p. 194. Patellaria incrustans 

 DC. Fl. Fr. ii. (1805) p. 361. 



Differs in the smaller, immersed, margined apothecia, which, if a con- 

 etant character, would render it a distinct variety. At times, however, 

 these in the same specimen become at length somewhat prominent and 

 immarginate, so that it can rank only as a form. 



Hob. On calcareous rocks in maritime and mountainous districts. - 

 Distr. Seen only from S.W. England, the S.W. Highlands, and the N. 

 Grampians, Scotland, though reported also by Leighton from W. England 

 (Ludlow, Shropshire). B. M. : Anstey's Cove, Torquay, S. Devon. 

 Island of Lismore, Argyleshire ; Morrone, Braemar, Aberdeenshire. 



Subsp. L. Siebenhaariana Nyl. ex Stiz. St. Gall. Nat. Ges. 1874, 

 p. 215. Thallus effuse, rimoso-areolate, unequal, whitish or greyish. 

 Apothecia small, adnate, convex, at first orange-coloured, at length 

 sordid-olive or brownish tawny-yellow, internally dark ; spores as 

 in the type. Cromb. Journ. Bot. 1885, p. 195. Biatora Sieben- 

 haariana, Koerb. Syst. Lich. Germ. (1855) p. 207. 



Characterized by the differently coloured apothecia and the dark hypo- 

 thecium. This, as observed by Fries fil., Lich. Scand. p. 425, in the 

 young apothecia is usually violet-rose-coloured, then becoming more and 

 more brownish, though in these it at times presents the natural colour of 

 the type. The thallus is at times almost evanescent and visible only 

 around the apothecia, which are small and scattered, or minute and 

 several congregate. 



Hob. On moist mica-schist rocks in alpine situations. Distr. Very 

 sparingly on two of the S. Grampians, Scotland. B. M. : Summits of 

 Ben Lawers and Craig Calliach, Perthshire. 



50. L. nivalis Nyl. Not. Sallsk. pro F. & Fl. F. Forh. v. (1866) 

 p. 129. Thallus effuse, very thin or slightly granulate, whitish or 

 greyish- white (K + purplish). Apothecia small, adnate, ochraceous 

 or orange-coloured, at first plane with an evanescent thalline mar- 

 gin, at length somewhat convex, biatorine with thin, entire proper 

 margin (K + purplish) ; spores oblongo-cylindrical, simple or faintly 

 1-septate, 0,024-38 mm. long, 0,005-7 mm. thick; paraphyses 



