406 LicHESACin. [lecanora. 



are evideutlv referable to Xylauder's plant, the tballns at first appears aa 

 small scattered ink-like stains upon tlie substratum, -wbich at lenorlh 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 verrucse are present, coloured blackish with smoke, as are also the 

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

 crowded. 



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

 — Distr. Confined apparently to the more open suburban districts of 

 London, where it is nut uncommon. — B. M. : Camden Town and Notting 

 Hill, London ; Crystal Palace, Surrey. 



Subsp. 2. L. dispersa Xyl. Flora, 1S73, p. 291. — Thalltis obsolete 

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

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

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

 0,0045-60 mm. thick : paraphyses slender, usually slightly iucrassate 

 at the apices. — Cromb. Grevillea, xviii. p. 68. — Lecmiora 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- 

 allv 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. 



Ilab. 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 Oswesti-y, Shropshire ; Hartlepool. Durham ; Cunswick Scar, 

 "Westmoreland. Achosragan Hill, Appin, Argvleshire ; Craig Tulloch, 

 Blair Athole, and Glen Lochay, KiUin, Perthshire : Moiione, Braemar, 

 Aberdeenshire. Clitfs of Moher, co. Clare: Delphi, Ccnnemara, co. 

 Galway. 



81. L. urbana Xyl.*'.*- Cromb. Journ. Bot. ISSo, p. 195. — Thallus 

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

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

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

 suberenulate : spores ellipsoid, 0,011-14 mm. long, 0,005-7 mm, 

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

 nienial gelatine bluish, the thecae at length sordid-violet or bluish 

 with \oAme. — Lecanor a galactina subsp. urhana Xyl. Bull. Soc. Bot. 

 t. xiii. (1866) p, 368. 



Difiers 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 

 ai'e numerous, crowded, often subangulose, with thickish, slightly crenate 

 margin. 



Hub. 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. : rs'ear Dorking, Surrey : Folkestone, Kent ; Lewes, Susse.x. 

 Cork. 



