PERTUSARIA.] LECANO-LECIDEEI. 503 



Hab. On trunks of old trees in upland districts. Distr. Only here and 

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

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

 Essex ; Albourne, Sussex ; New Forest, Hants ; Salpcrton, Gloucester- 

 shire ; Hay Park, Herefordshire ; Baysdale, Cleveland, Yorkshire. 



Form bacillosa Nyl. ex Lamy, Bull. Soc. Bot. t. xxv. (1878) 

 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 wooded upland situation. 

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

 New Forest, Hants. 



17. P. concreta Nyl. Mem. 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 confluent, thalline verrucas, endocarpoid, 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. PI. ed. 3, p. 227. 



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

 /. c.), the typical condition of " Isidium 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 papillae. 



Hab. On schistose rocks in a maritime district. Distr. Extremely 

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

 Galway. 



Form Westringii Nyl. Flora, 1876, p. 234. Thallus more or 

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

 elongate, subcyliudrical, simple and branched, brown at the apices. 

 Cromb. Grevillea, xix. p. 59. P. Westringii Leight. Lich. PI. 

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

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

 Crypt, fasc. iv. p. 20. Isidium Westrinc/ii Turn. & Borr. Lich. Br. 

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

 Eng. Fl. v. p. 239. 



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

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

 globules become dark- or reddish-brown. 



Hab. On rocks and walls in maritime and mountainous 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 

 Aberduvey, Merionethshire; Arkendale, Durham; Thornthwaite, near 



