PHVSCIA.] PHYSCIEI. 315 



15. P. melops Cut', (sub Parmelia) ex Nyl. Flora. 1874, p. 16. 

 Thallus orbicular, stellari-appressed, multifido-laciniate, more or less 

 cffisio-greyish ; lacinise narrow, contiguous, convex (K^yellow, 

 CaCl~). Apothecia small, plane, the thalline margin entire or at 



length slightly crenulate ; spores as in the preceding species. 

 Cromb. Journ. Bot. 1885, p. 195. 



Closely allied to P. aipolia, from which it differs chiefly in the darker 

 caesious thallus. Our single British specimen is sterile, with the thallus 

 not well developed. According to Nylander /. c. it is a widely distributed 

 saxicolous plant in the mountainous regions of Europe. 



Hob. On a calcareous wall among dead mosses in a maritime moun- 

 tainous district. Distr. Seen only in the S.W. Highlands of Scotland ; 

 no doubt to be detected elsewhere. B. M. : Appin, Argyleshire. 



16. P. tribacia Nyl. Flora, 1874, p. 48. Thallus orbicular or 

 subeffuse, moderate, shortly laciniate. glaucous-white or white, 

 sprinkled with small, subglobose, concolorous soredia, usually slightly 

 subfarinaceo-suffused : beneath whitish, with a few concolorous 

 fibrilloso rhizinae ; laciniae crowded, imbricate, digitato-crenate at 

 the apices (K+>' ellow , CaCl~). Apothecia moderate, scattered, 



blackish, the thalline margin subentire or subcrenulate ; spores 

 oblong, 0015-20 mm. long, 0,008-11 mm. thick. Cromb. Grevillea, 

 xv. p. 78. Borrera ccesia ft. tribacea Mudd, Man. p. 107. Squa- 

 maria tribacia Sm. Eng. Fl. v. p. 194 pro parte. Psoroma tribacium 

 Gray, Nat. Arr. i. p. 445. Lecanora tribacia Ach. Lich. Univ. 

 (1810) p. 415. 



A plant little understood by authors, allied to P. stellar is, with which 

 it agrees in the reactions. It differs, however, in the thallus being 

 generally covered with a thin farina, in the presence of soredia, and in 

 the more crowded laciniae being digitately crenate at the apices. In the 

 soredia it approaches P. ccesia, but differs in all other essential characters. 

 The apothecia are not present in the British specimens (cfr. Ach. I. t-.). 



Hab. On fruit-trees of orchards in maritime districts. Distr. Confined 

 to a few localities in S. England and the Channel Islands. B. M. : St. 

 Martin's, Island of Jersey. Lymington, Hants ; near Penzance, Cornwall. 



17. P. tribacoides Nyl. Flora, 1874, p. 307. Thallus orbicular, 

 small, shortly laciniate, whitish, sprinkled with small, subglobose, 

 white soredia, sparingly subfarinaceo-suffused ; beneath whitish, 

 nearly naked ; laciniae narrow, crowdedly imbricate, digitato-crenate 

 at the apices (K+ycllow, CaCl~). Apothecia not seen rightly 

 developed. Cromb. Grevillea, iii. p. 22 j Leight. Lich. Fl. ed. 3, 

 p. 140. 



Subsimilar to the preceding species, from which, besides other charac- 

 ters, it at once differs in the reaction of the medulla with K. In the 

 specimen gathered there are only two young apothecia. 



