LECANOBA.] LECANO-LECJDEEI. 419 



Lecanora peralbella Nyl. Flora, 1872, p. 365 : Leight. Lich. Fl. ed 3 

 p. 206. 



Originally regarded by Nylander as specifically distinct, this is now 

 viewed by him only as a ibrm characterized by the reaction of the 

 hymenial gelatine. 



Hob. On thorns and trunks of trees in a maritime district Distr. Very 

 rare in N.AV. Ireland. B. M. : Killery Bay and Ballynahinch, Con- 

 neuiara, co. Galway. 



Form 2. subalbella Xyl. ex Hue, Rev. Bot. 1887, p. 161. 

 Spores 0,009-11 mm. long, 0,005-7 mm. thick; hymenial gelatine 

 and the thecae bluish, then darker with iodine. Cromb. Grevillea, 

 xviii. p. 68. Lecanora subalbella Nyl. Flora, 1872, p. 365. Lichen 

 rosellus Eng. Bot. t. 1651 (apotheciis magis convexis). 



Only another form of L. albella, though more distinct than the pre- 

 ceding, differing not merely in the reaction of the hymenial gelatine but 

 also in the slightly smaller spores and the slightly longer spermatia, which 

 fide Nylander are 0,016-22 mm. long. 



Hab. On the trunks of trees in wooded maritime and upland tracts. 

 Distr. Only sparingly in S. England. B. M. : Netley Abbey, near Bartly 

 Lodge, and Bramble Hill, New Forest, Hants. 



99. L. angulosa Ach. Lich. Univ. (1810) p. 364 ; Nyl. Flora, 

 1872, p. 250. Thallus determinate, thin, smooth, at length unequal 

 or rugoso-subrimose, greyish-white (K + yellow, CaCl ). Apo- 

 thecia small or submoderate, plane or slightly convex, crowded and 

 subangulose, pale-brown or sordid-pale, slightly caesio-pruinose 

 (epitheciuin CaCl + yellow); the thalline margin thin, subentire or 

 somewhat crenulate, at length subevanesceiit ; paraphyses slender, 

 subdiscrete ; epithecium granulose ; spores 0,009-16 mm. long, 

 0,006-9 mm. thick; hymenial gelatine persistently bluish with 

 iodine. Leight. Lich. Fl. ed. 3, p. 205. L. albella subsp. angulosa 

 Cromb. Lich. Brit. p. 51 ; var. /3. angulosa Mudd, Man. p. 148. 

 L. subfusca var. angulosa Leight. Lich. Fl. ed. 1, p. 204. Lichen 

 angulosus Schreb. Spicil. (1771) p. 136. Brit. EMS. : Mudd, nos. 

 114, 115. 



Usually regarded as only a variety (or subspecies) of L. albella, this 

 essentially differs in the positive reaction of the epithecium with CaCl, 

 and in the black colour of the spermogones above. Among minor cha- 

 racters it also differs in the crowded angulose apothecia, especially in the 

 centre of the thallus, and in the rather larger spores. The spermatia are 

 shorter than in the preceding species, being (Jide Nyl. in litt.) 0,014-18 

 mm. long. 



Hab. On trunks of trees, rarely on old pales, in maritime and upland 

 districts. Distr. Here and there in Great Britain and Ireland ; not seen 

 from the Channel Islands. B. M. : Kpping Forest, Essex ; near Lewes 

 and Hastings, Sussex ; New Forest, Hants ; Ullacombe, Bovey Tracey, 

 S. Devon ; Cirencester, Gloucestershire ; Cliffrigg and near Easby, Cleve- 

 land, Yorkshire ; Catterleen, Cumberland. Appin, Argyleshire ; Finlarig, 



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