406 LICHENACEI. [LECAXORA. 



are evidently referable to Nylander's plant, the thallus at first appears as 

 small scattered ink-like stains upon the substratum, which at length be- 

 come confluent, so that it spreads extensively without any distinct limits. 

 For the greater part it is only hypothalline, but here and there a few thai- 

 line verrucae are present, coloured blackish with smoke, as are also the 

 gonidia (form fumigata Cromb.). The apothecia are numerous and 

 crowded. 



Hob. On composite walls and pillars of houses in lowland tracts. 

 Distr. Confined apparently to the more open suburban districts of 

 London, where it is not uncommon. B. M. : Camden Town and Notting 

 Hill, London ; Crystal Palace, Surrey. 



Subsp. 2. L. dispersa Nyl. Flora, 1873, p. 291. Thallus obsolete 

 or entirely wanting. Apothecia minute, more or less scattered, 

 pale-livid, subcarneous or blackish, naked or pruinose, the thalline 

 margin white, entire or subcreuulate ; spores 0,009-14 mm. long, 

 0,0045-60 mm. thick ; paraphyses slender, usually slightly incrassate 

 at the apices. Cromb. Grevillea, xviii. p. 68. Lecanora galactina 

 form dispersa Leight. Lich. Fl. p. 206, ed. 3, p. 190. 



A good subspecies, characterized chiefly by the absence of a distinct 

 thallus. It spreads extensively over the substratum, and as it occasion- 

 ally grows associated with less developed states of the type, it probably 

 descends from some of these. The apothecia are usually somewhat scat- 

 tered, though at times rather crowded in the same specimen. 



Hob. On rocks and walls in maritime and upland tracts. Distr. Only 

 here and there in Great Britain and Ireland ; not seen from the Channel 

 Islands. B. M. : Ryde beach, Isle of Wight ; Cirencester, Gloucester- 

 shire ; near Oswestry, Shropshire ; Hartlepool, Durham ; Cuuswick Scar, 

 Westmoreland. Achosragan Hill, Appin, Argyleshire ; Craig Tulloch, 

 Blair Athole, and Glen Lochav, Killin, Perthshire ; Morrone, Braemar, 

 Aberdeenshire. Cliffs of Moher, co. Clare ; Delphi, Connemara, co. 

 Gal way. 



81. L. urbana Nyl. ex Cromb. Journ. Bot. 1885, p. 195. Thallus 

 subdeterminate, moderate, granulato-squamulose, white, opaque ; 

 granules depressed, crenate or subcrenate (K-). Apothecia mode- 

 rate, crowded, pale, more or less white-suffused, the thalline margin 

 subcrenulate ; spores ellipsoid, 0,011-14 mm. long, 0,005-7 mm. 

 thick; paraphyses thickish, jointed, not clavate at the apices; hy- 

 menial gelatine bluish, the theca? at length sordid-violet or bluish 

 with iodine. Lecanora galactina subsp. urbana Nyl. Bull. Soc. Bot. 

 t. xiii. (1866) p. 368. 



Differs from L. galactina in the thicker, whiter thallus, the longer 

 spores, and more especially in the paraphyses being twice or thrice as 

 thick and distinctly articulate. In the British specimens the apothecia 

 are numerous, crowded, often subangulose, with thickish, slightly crenate 

 margin. 



Hob. On mortar of old walls near towns in lowland districts. Distr. 

 Only in S. England and S. Ireland : no doubt to be detected elsewhere. 

 B. M. : Near Dorking, Surrey ; Folkestone, Kent ; Lewes, Sussex. 

 Cork. 



