176 LECANO-LBCIDBEI [bDELLIA 



i. p. 237, t. 32, figs. 1 & 2 (1878) & Lich. Fl. ed. 3, p. 324. 

 Specimen not seen. 



Considered by Leighton to be allied to tbe preceding, but differs in 

 the appearance of the apothecia and in the larger spores. By the 

 contiguous growth of several plants on the same stone, the surface 

 becomes intersected by dark lines. 



Hah. On bluish-grey slates. — Distr. Rare in bill y regions in 

 Wales. 



24. B. subdisciformis Jatta Syll. Lich. Ital. p. 392 (1900). 

 — Thallus determinate, thickish, minutely cracked-areolate, the 

 areolae plane, sordid-yellowish-white (K + yellow then red, 

 CaCl — , medulla I — ) ; hypothallus black, limiting the thallus. 

 Apothecia sessile, plane, marginate, blackish, more or less pruinose, 

 the margin thick, entire, paler ; hypothecium black ; paraphyses 

 discrete; hymenium pale-brown; spores oblong, brown, 0,011-16 

 mm. long, 0,007-8 mm. thick. — Lecidea subdisciformis Leight. 

 Lich. Fl. p. 308 (1871) ; ed. 3, p. 322. 



Exsicc. Larb. Lich. Csesar. n. 35. 



Distinguished from allied species by the strongly marked hypo- 

 thallus which occasionally intersects the thaUus, and by the chemical 

 reaction. 



Hah. On rocks. — Distr. Somewhat rare in the Channel Islands, 

 S. and Central England, Wales and N. and W. Ireland. — B. M. Jer- 

 bourg, Guernsey ; Noirmont, Jersey ; Sark ; Lamoma, Cornwall ; 

 Torquay, Devon ; North Hill, Malvern, Worcestershire ; Conway, 

 Carnarvonshire; Kinsale, Cork. 



Var. meiosperma Steiner in Verb. K. K. Zool.-Bot. Ges. 

 "Wien Ivii. p. 363 (1907). — Thallus as in the type. Apothecia 

 often bluish-grey pruinose ; spores smaller, 0,009-12 mm. long, 

 0,005-7 mm. thick. — Lecidea disciformis var. meiosperma Nyl. in 

 Flora li. p. 478 (1868); Cromb. Lich. Brit. p. 88. L. subdisci- 

 formis var, meiosperma Leight. Lich. Fl. p. 308 (1871) ; ed. 3, 

 p. 322. 



Hab. On rooks. — Distr. Eare in the Channel Islands. — B. M. 

 Jersey ; the Eperquerie, Sark. 



25. B. disciformis Mudd Man. p. 216 (1861) pro parte.— 

 Thallus determinate, thin, smooth, continuous, unequal or 

 cracked-areolate, whitish or greyish- white, (K -)- yellow, CaCl — ); 

 hypothallus thin, black, limiting the thallus. Apothecia sessile, 

 moderate or somewhat small, plane and thinly margined, at 

 length convex and almost immarginate, black ; hypothecium 

 dark-brown or black ; paraphyses subconcrete, brownish at the 

 apices, branched and capitate; spores ellipsoid or oblong, 

 0,019-30 mm. long, 0,008-0-014 mm. thick; hymenial gelatine 

 bluish with iodine. — Lecidea disciformis Xyl. in Bot. Not. 1852, 

 p. 175; Cromb. Lich. Brit. p. 88; Leight. Lich. Fl. p. 305; 



