LKCAXOHA.j li;(axo-t,fcii)i:ki. 1^5." 



Form dispersa Loiglil. Lidi. Fl. ed. 3(1870), p. 1")!). — 'J'h.ilhis 

 pulviiiato, the imlvinuli more or less distantly scattered, rounded, 

 tujiid, convex, white-suft'used. Apothceia innate, minute, crowded. 



A peculiar form which at first sijrht seems very di.stinct, but is 

 connected with tiie type by the state already noticed. Tlie apothecia are 

 numerous, becomiug angulose iVom uuitual pressure. 



ILih. On calcareous rocks in a maritime district. — Disfr. Only in 

 N. Wales arid apparently very rare. — B. M, : (ireat Orme's Head, Carnar- 

 vonshire. 



Subsp. L. albomarginata Nyl. e.v CVorab. 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, intlexed or crenate, white. — Lecanora 

 saxicola var. alhomroyinatd Leight. Lich. Fl. ed. 3, p. 159. Squa- 

 maria saxicola var. aJhomarjuiata Nyl. Not. ^iillsk. pro F. et Fl. F. 

 Fiirh. 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 Britisli specimen seen 

 the thallus is orbicular and moderate, the apothecia being somewhat 

 crowded in the centre. 



Hob. Incrusting decayed mosses on rocks and walls in upland situa- 

 tions. — Did)-. Local and scarce in S. and W. England.— B. M. : Near 

 Lewes, Sussex ; Cheshire. 



7. L. priiinifera Nyl. Bull. Soc. Bot. Fr. t. 13 (186G) p. 3G8, 

 not. 2. — Thallus orbicular, opaque, whitish, subfarinaceous on the 

 surface, placodioid at the circumference (CaCl + red). Apothecia 

 moderate, caesio-pruinose, the thalline margin subcrenate or some- 

 times eutire; spores ellipsoid, 0,010-13 mm. long, U, 005-6 mm. 

 thick; hymenial gelatine bluish, then sordidly tawny-yellow with 

 iodine. — Cromb. Journ. Bot. 1882, p. 274. — Lecanora 2^''tt<i^osa 

 Chaub. in 8t. Amaud. Fl. Agen. (1821) p. 495 has priority, but was 

 previously applied to another species of the genus. 



Near var. j3 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. — Di-sf?: Found only 

 very sparingly in W. England. — B. M. : Cleve Hill, Somersetshire. 



Subgen. 3. PLACOPSIS Xyl. Ann. Sc. Nat. Bot. t. sv. (1862) 

 p. 376. — Thallus crustaceo-adnate, more or less effigurate at the 

 circumference, cephalodiiferous, the ccphalodia externally placo- 

 dioid, internally containing gonimia. Apothecia lecanorine ; thecce 

 cylindrical ; spores Snte, oblong or ellipsoid, simple ; paraphyses 

 slender ; hymenial gelatine bluish with iodine. Spermogones with 

 simple sterigmata and arcuate or substraight spermatia. 



2a2 



