252 GRAPHIDBI [PH^OGRAPHIS 



92. PHJIOGRAPHIS Muell.-Arg. in Flora Ixv.p. 336 (1882). 

 Hymenodecton Leight. in Ann. Mag. Nat. Hist. ser. 2, xiii. p. 279 

 (1854). CMographa Leight. I. c. p. 388. (PI. 29.) 



Thallus urustaceous, thin, superficial or developed under the 

 bark (hypophloeodal). Algal cells Trentapohlia. Apothecia {lirellse) 

 elongate, rarely roundish, immersed then erumpent, simple or 

 branched ; disc narrow and slit-like or expanded ; proper margins 

 prominent or disappearing ; hypothecium colourless or dark- 

 coloured ; asci clavate or elongate, usually 8-spored ; spores 

 brown, or colourless then brown, elongate, pluriseptate. 



Mueller's arrangement of Oraphis and the allied genera has been 

 followed in order to avoid confusion. Earlier generic names, with 

 undoubted claims to consideration, have been rejected as being too 

 vague or too restricted in definition. The two genera Hymenodecton 

 and CMographa were formed by Leighton to mark the difference in 

 the formation of the outer carbonaceous wall of the apothecium : in 

 the former the wall is continuous round the base as a thin dark layer ; 

 in the latter it is developed only at the sides (dimidiate), and the 

 colourless hypothecium rests on the substratum. More recently 

 Crombie and Leighton included all the species under Graphis. 



1. Ph. inusta Muell.-Arg. in Plora Ixv. p. 383 (1882).— 

 Thallus greyish or whitish, thin, membranaceous, smooth or 

 wrinkled. Apothecia black, immersed, usually rather short and 

 broad, obtuse at the ends, simple or branched ; proper margins 

 very narrow, with a thin thalloid border ; disc plane, naked or 

 pruinose ; hypothecium colourless ; paraphyses slender, brownish 

 at the slightly clavate tips ; spores elongate-linear, becoming 

 dark-brown, 5-7-septate, 0,028-38 mm. long, 0,009 mm. thick. — 

 Opegrapha scripta Sm. Engl. Bot. t. 1813 (1807) (non Ach.). 

 Graphis inusta Ach. Syn. p. 85 (1814) ; Mudd Man. p. 240 (incl. 

 var. vera) ; Cromb. Lich. Brit. p. 97 ; Leight. Lich. Fl. p. 368 ; 

 ed. 3, p. 431 (incl. f. vera). O. Smithii Leight. in Ann. Mag. 

 Nat. Hist. ser. 2, xiii. p. 278, t. 6, f. 22 (1854) (incl. var. vera). 



Exsico. Larb. Lich. Caesar, n. 89. 



In the typical form described by Achariug (f. vera Leight.) the 

 thallus is sometimes surrounded by a dark line ; the apothecia are 

 short and stellately arranged in crowded or scattered groups. It is 

 distinguished from other British members of the genus by the 

 distinctly dimidiate apothecia, the carbonaceous walls being developed 

 at the sides only. 



Hob. On the bark of various trees. — Distr. Bather rare in the 

 Channel Islands, S. and Central England, and S. and W. Ireland, not 

 yet recorded from Scotland. — B. M. Beaumont, St. Lawrence, Jersey ; 

 Withiel, Cornwall; Lustleigh and near Lidford, Devon; Kemble, 

 Wilts ; near Lyndhurst, New Forest, Hants ; St. Leonard's Foresb 

 and Hurst, Sussex ; Epping Forest, Hockley Woods, Hadleigh Woods, 

 and G-osfield Hall, Essex ; Hollybush Hill, Malvern, Worcestershire ; 

 Glenbower Wood, Cork ; Clonmel, Tipperary. 



Form divarioata A. L. Sm. — Thallus similar to that of the 

 species. Apothecia more elongate and scattered, occasionally 



