PERTUSABIA.] LECAXO-I.ECIDEEI. 503 



Hub. Ou trunks of old trees iu upland districts. — Distr. Only here and 

 there throughout England ; not seen in Scotland or Ireland. — B. M. : 

 Near Norwich, Norfolk ; near Quendou, Epping and Hainault Forests, 

 Essex; Albourne, Sussex; New Fore-st, Hants; Salporton, Gloucester- 

 shire ; Hay Park, Herefordshire ; Jiaysdale, Cleveland, Yorkshire, 



Form bacillosa Xyl. ex Lamy, Bull. See. Bot. t. xxv. (187S) 

 p. 425. — Thallus covered with numerous, long, isidioid papillae 

 •which are obtuse and branched. — Cromb. Grevillea, xix. p. 59. 



Only a very luxuriant though well-marked condition of the type. It 

 is always sterile. 



Hab. On the trunk of an old tree in a Avooded upland situation. — 

 Distr. Only very sparingly in S. England. — B. M. : Near Lyndhurst, 

 New Forest, Hants. 



17. P. concreta Xyl. Me'm. Soc. Cherb. v. (1857) p. 117 ; Flora, 

 1876, p. 234. — Thallus determinate, continuous, thickish, rimose, 

 unequal, white or whitish, subeffigurate at the circumference 



(K '\ yellow, then saffron-red). Apothecia immersed in convex, 



variously couliuent, thalline verrucfe, endocarpcid, colourless, 

 indicated externally by a dark punctiform ostiole ; spores 0,015- 

 25 mm. long, 0,052-080 mm. thick. — Cromb. Grevillea, v. p. 25 ; 

 Leight. Lich. Fl. ed. 3, p. 227. 



A rather interesting plant, forming, as observed by Nylauder (Flora, 

 /. c), the typical condition of " Isidiitm Westringii," the relation of 

 which to the allied species had previously been very uncertain. On the 

 thallus of the Irish specimens, which are well fertile, traces occur here 

 and there of a few short abortive papilke. 



Hub. On .schistose rocks in a mnritime district. — Distr. Extremely 

 local and scarce in N.W. Ireland. — B. M. : Letterfrack, Connemara, co. 

 Galway, 



Form Westringii Xyl. Flora, 1876, p. 234. — Thallus more or 

 less densely papillose ; papillae at first minute, subglobose, then 

 elongate, subcylindrical, simple and branched, browTi at the apices. 

 Cromb. Grevillea, xix. p. 59. — P. Westrinr/ii Leight. Lich. Fl. 

 p, 236, ed, 3, p. 227 pro minima parte. Lichen Westringii Ach. 

 Yet. Ak. Handl, 1794, p. 179, t. 6. f. 1 ; Eng. Bot. t. 2204 ; Dicks. 

 Crypt, fasc. iv. p. 20, Isidiinn We.^ti-in(jii Turn. & Borr. Lich, Br. 

 p. 92 ; Gray, Xat. Arr, i, p. 412 ; Hook. Fl. Scot, ii, p. 66 ; Sm. 

 Eng, Fl, Y, p. 239. 



Only a sterile isidioid condition, though at first sight appearing very 

 distinct. The papdlce are sometimes 2-3 confluent, and in age the apical 

 globules become dark- or reddish-brown. 



Sab. On rocks and walls in maritime and moimtainous districts. — 

 Distr. Here and there throughout Great Britain ; rare in the Channel 

 Islands and W. Ireland ; probably often overlooked. — B. M. : Island of 

 Guernsey. Near St. Austell and Penzance, Cornwall; Barmouth and 

 Aberdovey, Merionethshire ; Aikendale, Durham ; Thornthwaite, near 



