opegrapha] graphidaok^ 231 



Form arthonoidea Leight. Lich. Fl. ed. 3, p. 397 (1879).— 

 Thallus as in the preceding variety. Apothecia suborbicular, 

 innate, immarginate, plane. — Opegrapha rufescens var. arthonoidea 

 Schser. Spicil. p. 328 (1836). 



Sab. On ash trees. — Distr. Bare in England. — B. M. Chalford, 

 Gloucestershire. 



Var. subocellata Ach. Syn. p. 73 (1814). — Thallus somewhat 

 pulverulent. Apothecia small, oblong, simple or substellate, 

 embedded in the thallus and surrounded by a white margin. — 

 Leight. in Ann. Mag. Nat. Hist. ser. 2, xiii. p. 206 (1854) & 

 Lich. Fl. p. 374 ; ed. 3, p. 396 ; Mudd Man. p. 234 ; Cromb. 

 Lich. Brit. p. 99. 



Exsicc. Leight. n. 222. 



Kegarded by Nylander as a variety of 0. rufescens. It is easily 

 recognized by the spurious white margin of the apothecia. The 

 spermatia in our British specimens so far as observed are minute and 

 somewhat ovoid, 0,003 mm. long and 0,001-2 mm. thick. 



Hab. On trees. — Distr. Frequent in N. and S. England, rare in 

 Wales, the Channel Islands, and Ireland. — B. M. Near Exeter and 

 near Becky Falls, Devon ; New Forest, Hants ; near Bath, Somerset ; 

 TUgate, near Clayton ; near Glynde and Balcombe, Sussex ; Epping 

 Forest, Essex ; Airyholme Wood, Easby Wood, and Cliffrigg, Cleve- 

 land, Yorkshire; KUlarney, Kerry. 



2. 0. contexta Stirton in Grevillea iii. p. 35 (1874). — Thallus 

 reddish-buff-coloured, thin, limited by the brown hypothallus. 

 Apothecia small, black, flattened, roundish, usually aggregate, 

 the disc gyrose-plicate ; hypothecium blackish-brown ; paraphyses 

 indistinct ; spores fusiform, blunt at the apices, 3-septate, 

 colourless, 0,017-25 mm. long, 0,0045 mm. thick. — Leight. Lich. 

 Fl. ed. 3, p. 403. Specimen not seen. 



Perhaps only a form of the preceding. 



Hab. On elm, near Grantown, Invemessshire. 



3. 0. atra Pers. in Ust. Ann. Bot. vii. p. 30 (1794).— 

 Thallus thin, forming whitish or yellowish patches, sometimes 

 limited. Apothecia black, numerous, lying in all directions or 

 subparallel, linear, usually simple, flexuose ; disc slit-like, narrow, 

 uniform, the margins thick, elevated, wavy ; hypothecium dark, 

 reddish upward ; spores obovate-fusiform, 3- or rarely 4-septate, 

 colourless, rather small, 0,014-20 mrn. long, 0,004 mm. thick. — 

 Hook, in Sm. Engl. Fl. v. p. 145 pro parte ; Tayl. in Mackay Fl. 

 Hib. ii. p. 105 ; Leight. in Ann. Mag. Nat. Hist. ser. 2, xiii. 

 p. 203, t. 5, f. 11 (1854) & Lich. Fl. p. 375; ed. 3, p. 398 

 (incl. f. tenuior Nyl. ex Leight. Z. c. ed. 3, p. 400 (1879)) ; Mudd 

 Man. p. 232 ; Oromb. Lich. Brit. p. 98 pro parte. 0. denigrata 

 Sm. Engl. Bot. t. 1753 (1807) (non Ach.). 



Exsicc. Mudd nos 208, 206 ; Leight. n. 220 (the two latter 



