PHYSOIA. | PHYSCIEI. 315 
15. P. melops Duf. (sub Purmelia) ex Nyl. Flora, 1874, p. 16.— 
Thallus orbicular, stellari-appressed, multifido-laciniate, more or less 
ceesio-greyish; lacinie narrow, contiguous, convex (KTyellow, 
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 
cesious thallus. Our single British specimen is sterile, with the thallus 
not well developed. According to Nylander J. ¢. it isa widely distributed 
saxicolous plant in‘the mountainous regions of Europe. 
Hab. On a calcareous wall among dead mosses in a maritime moun- 
tainous district.—Distr. Seen only in the 8.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 
fibrillose rhizinee ; laciniz crowded, imbricate, digitato-crenate at 
the apices (Kt¥"O¥ Cucl—). 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 cesia 3. tribacea Mudd, Man. p. 107. Squa- 
marta 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. stellaris, 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 laciniz being digitately crenate at the apices. In the 
soredia it approaches P. cesta, but differs in all other essential characters. 
The apothecia are not present in the British specimens (¢/r. Ach. @. ¢.). 
Hab. On fruit-trees of orchards in maritime districts. —Disty. Confined 
to a few localities in 8. Englavd and the Channel Islands.—B. M.: St. 
Martin’s, Island of Jersey. Lymington, Hants; near Penzance, Cornwall. 
17. P. tribacoides Nyl. Flora, 1874, p. 807.—Thallus orbicular, 
small, shortly laciniate, whitish, sprinkled with small, subglobose, 
white soredia, sparingly subfarinaceo-suffused; beneath whitish, 
nearly naked ; laciniz narrow, crowdedly imbricate, digitato-crenate 
at the apices (K{yellow, CaCl_). Apothecia not seen rightly 
developed.—Cromb. Grevillea, iii. p. 22; 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. 
