444 LICHENACEI. [LECANORA. 



Lecania erysibe Mudd, Man. p. ]41 pro parte, t. ii. f. 47. Lichen 

 erysibe Ach. Prodr. (1798) p. 50. L. ertjsibe ft. Rabenhorstii (Hepp), 

 Mudd, Man. /. c. is entirely confluent with the type. Brit. Exs. : 

 Mudd, nos. 104, 105. 



A very variable plant, tibe differences in the thallus and apothecia of 

 which give rise to the forms, varieties, and subspecies that follow. With 

 its usually biatoroid apothecia it is at times not unlike Lecidea rubella 

 (Ehrh.), of which Acharius (Lich. Univ. p. 196) makes it a variety. 

 The apothecia are occasionally aggregate, and become darker in age. 

 The spermogones, which are not very frequent in our specimens, have the 

 spermatia 0,015-18 mm. long, 0,0005 mm. thick. 



Hub. On rocks, very rarely on decorticated trunks of trees, in maritime 

 and upland districts. Distr. Here and there throughout Great Britain ; 

 apparently rarer in the Channel Islands and Ireland. B. M. : St. Aubin's 

 Fort, St. John's and St. Brelade's (lignicolous), Island of Jersey. Rot- 

 tingdean Cliffs, Sussex ; near Torquay, S. Devon ; near Peuzance, Corn- 

 wall ; Norton, Worcestershire ; near Ayton and Coatham, Cleveland, 

 Yorkshire ; St. Bees, Cumberland. Island of Lismore and Barcaldine, 

 Argyleshire ; Portlethen, Kincardineshire ; Craig Guie, Braemar, Aber- 

 deenshire. Lower Glanmire Road, co. Cork ; near Kilkee, co. Clare ; 

 co. Down. 



Form cinereofusca, Cromb. Grevillea, xviii. (1890) p. 69. 

 Thallus very thin, greyish-brown. Apothecia minute, plane, at 

 length convex, dark-brown, slightly pruinose ; spores indistinctly 1- 

 septate, often 2-3-nucleolate. Lecania erysibe var. I. cinereofusca 

 Mudd, Man. (1861) p. 141, t. 2. f. 48. Brit. Ers. : Mudd, n. 106. 



Only a form with thinner thallus and smaller subpruinose apothecia, 

 the pruina disappearing in age. Apparently it is confluent with the type 

 and results from the habitat. 



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

 sparingly in S., W., and N. England. B. M. : Hastings, Sussex ; Crowle, 

 near Worcester ; near Ayton, Cleveland, Yorkshire. 



Var. ft. sincerior Nyl. Flora, 1876, p. 577. Thallus subgranu- 

 late, areolato-rimose, pale-greyish or subochraceo-whitish. Apo- 

 thecia lecanorine, pale-brown, the thalline margin persistent. 

 Cromb. Grevillea, v. p. 108 ; Leight. Lich. Fl. ed. 3, p. 219. 



Differs in the colour of the more granulate thallus and in the per- 

 sistently lecanorine apothecia. Nylander /. c. observes that it may rank 

 as a subspecies. 



Hab. On schistose and arenaceous rocks and walls in maritime tracts. 

 Distr. Found sparingly in the Channel Islands, S. and N. England, and 

 N.W. Ireland. B. M. : La Coupe, Island of Jersey. Hastings, Sussex ; 

 near Torpoint, S. Devon ; St. Bees, Cumberland ; North Tyne, North- 

 umberland. Lettermore, Connemara, co. Galway. 



Subsp. 1. L. albariella Nyl. Flora, 1881, p. 454. Thallus areo- 

 lato-diffract, whitish-cream-coloured. Apothecia biatorine, smaller 

 submoderate, brown or brownish-black ; spores ovoid, 1-septate, 

 0,012-16 mm. long, 0,005-6 mm. thick ; hymenial gelatine at length 



