LITHORBAPHA] GEAPHIDACBa: 221 



preceding Natural Orders. It is represented in Britain by the 

 following genera : — 



Thallus with Palmella gonidia ; apotheoia oblong or oval. 

 Spores simple, colourless. 

 Hymenium simple. 



Apothecia carbonaceous 85. Litliographa. 



„ not carbonaceous ... 86. Xylograplia. 



Hymenium compound 87. Ptycliographa. 



Spores 1-septate, brown 88. Encephalographa. 



Thallus with Trentejpohlia gonidia ; apotheoia elongate or roundish. 



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

 Spotes 3-pluri-septate. 



Apotheoia superficial 90. Opegrapha. 



Apotheoia immersed. 



Spores colourless 91. G-raphis. 



Spores brown 92. PhaeograpMs. 



Spores muriform 93. Graphina. 



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

 i. p. 393 (1856). (PI. 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. torn. 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; hymenial 

 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 areolse 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 ; Holwiok Scar, Teesdale, Durham ; Ben Lawers, 

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

 Appleoross, Eossshire. 



