LITHOGRAPH a] GRAPHIDACEiE 221 



preceding Natural Orders. It is represented in Britain by the 

 following genera : — 



Thallus with Pahnella gonidia ; apothecia oblong or oval. 

 Spores simple, colourless. 

 Hvinenium simple. 



Apothecia carbonaceous 85. Lithographa. 



,, not carbonaceous ... 86. Xylographa. 



Hymenium compound 87. Ptychographa. 



Spores 1-septate, brown 88. Encephalographa. 



Thallus with Trentejmhlia gonidia ; apothecia elongate or roundish. 



Spores 1-septate, colourless or brown ... 89. Melaspilea. 

 Spores 3-pluri-septate. 



Apothecia superficial 90. Opegrapha. 



Apothecia immersed. 



Spores colourless 91. Gr aphis. 



Spores brown 92. Phasographis. 



Spores muriform 98. Graphina. 



85. LITHOGRAPHA Nyl. in Act. Soc. Linn. Bord. ser. 3, 

 i. p. 393 (1856). (PL 22.) 



Thallus crustaceous, sometimes evanescent. Algal cells 

 Palmella. Apothecia shortly elongate, lirelliform, carbonaceous, 

 the disc usually narrow, the margins prominent, inflexed ; hypo- 

 thecium usually dark-coloured ; paraphyses very rarely discrete ; 

 asci clavate, 8- or poly-spored ; spores simple, colourless. 



1. L. tesserata Nyl. tom. cit. p. 441 & Lich. Scand. p. 290. — 

 Thallus thickish, verrucose-areolate or areolate-rimose, greyish, 

 pale-greyish-brown or whitish (K + yellow then reddish, 

 CaCl — ). Apothecia moderate in size, rather prominent, shortly 

 lirelliform, obtuse, simple or at times divided, black, the margin 

 somewhat shining ; disc narrow; paraphyses irregular or indistinct ; 

 hypothecium thick, blackish-brown ; spores 8 in the ascus, oblong 

 or ellipsoid, 0,008-15 mm. long, 0,005-8 mm. thick; hyraenial 

 gelatine pale-bluish then tawny- wine-red with iodine. — Mudd 

 Man. p. 225, t. 4. fig. 87 ; Cromb. Lich. Brit. p. 95 ; Leight. 

 Lich. Fl. p. 360 ; ed. 3, p. 393. Opegrapha tesserata DC. Fl. 

 Franc, ii. p. 313 (1805) ; Borr. Engl. Bot. Suppl. t. 2632, f. 2 ; 

 Hook, in Sm. Engl. Fl. v. p. 146 ; Leight. in Ann. Mag. Nat. 

 Hist. ser. 2, xiii. p. 88, t. 5, f. 1 (1854). 



Exsicc. Leight. n. 396. 



The thalline areolae are either contiguous or somewhat scattered, 

 the black hypothallus being more or less visible. The apothecia, 

 variable in form, are either solitary or crowded and congested. 



Hab. On rocks from upland to alpine situations in mountainous 

 regions. Distr. With certainty only in N. Wales, N. England, on the 

 Grampians, and in the N.W. Highlands of Scotland. — B. M. Near 

 Lyn Aran and Cader Idris, Merioneth ; Capel Curig, Cwm Clyd, 

 Nant Francon, Snowdon, Carnarvonshire ; near Stavely, Kendal, 

 Westmoreland ; Holwick Scar, Teesdale, Durham ; Ben Lawers, 

 Perthshire ; summit of Morrone, Braemar, Aberdeenshire ; Hills of 

 Applecross, Rossshire. 



