LECANORA. | LECANO-LECIDEEL. 855 
Form dispersa Leight. Lich. Fi. ed. 3 (1879), p. 159.—Thallus 
pulvinate, the pulvinuli more or less distantly scattered, rounded, 
tunid, convex, white-suffused. Apothecia innate, minute, crowded. 
A peculiar form which at first sight seems very distinct, but is 
connected with the type by the state already noticed. The apothecia are 
numerous, becoming angulose from mutual pressure. 
#Zab, On calcareous rocks in a maritime district.—Distr. Only in 
N, yes and apparently very rare.—B.M.: Great Orme’s Head, Carnar- 
vonshire. 
Subsp. L. albomarginata Nyl. ea Cromb. Journ. Bot. 1874, 
p. 147.—Thallus thicker, less appressed, with the radii broader, 
subimbricate, white at the margins. Apothecia somewhat large, 
the thalline margin thickish, inflexed or crenate, white.— Lecanora 
saxicola var. alhomaryinata Leight. Lich. Fl. ed. 8, p. 159. Squa- 
maria saxicola var. albomarginata Nyl. Not. Sallsk. pro F. et Fi. F. 
Forh. xi. (1871). p. 181. 
Entitled to rank as a subspecies on account of the marked difference in 
the characters of the thallus. In the only entire British specimen seen 
the thallus is orbicular and moderate, the apothecia being somewhat 
crowded in the centre. 
Hab. Incrusting decayed mosses on rocks and walls in upland situa- 
tions. —Distr. Local and scarce in 8. and W. England.—B. M.: Near 
Lewes, Sussex; Cheshire. 
7. L. pruinifera Nyl. Bull. Soc. Bot. Fr. t. 13 (1866) p. 368, 
not. 2.—Thallus orbicular, opaque, whitish, subfarinaceous on the 
surface, placodioid at the circumference (CaCl+red). Apothecia 
moderate, ceesio-pruinose, the thalline margin subcrenate or some- 
times entire; spores ellipsoid, 0,010-13 mm. long, 0,005-6 mm. 
thick; hymenial gelatine bluish, then sordidly tawny-yellow with 
iodine-—Cromb. Journ. Bot. 1882, p. 274.—Lecanora pruinosa 
Chaub. in St. Amand. Fl. Agen. (1821) p. 495 has priority, bufi was 
previously applied to another species of the genus. 
Near var. 8 of the preceding species, but at once differing in the sub- 
farinaceous thallus, the pruinose apothecia, and the chemical reaction. 
In our only British specimen the thallus is small and the apothecia few. 
Hab, On calcareous rocks in an upland tract.—Distr. Found only 
very sparingly in W. England.—B. M.: Cleve Hill, Somersetshire. 
Subgen. 3. PLACOPSIS Nyl. Ann. Se. Nat. Bot. t. xv. (1862) 
p. 376.—Thallus crustaceo-adnate, more or less effigurate at the 
circumference, cephalodiiferous, the cephalodia externally placo- 
dioid, internally containing gonimia. Apothecia lecanorine; theca 
cylindrical; spores 8nz, oblong or ellipsoid, simple; paraphyses 
slender; hymenial gelatine bluish with iodine. Spermogones with 
simple sterigmata and arcuate or substraight spenmalias . 
ZAZ 
