388 Rev. W. A. Leigh ton on the British Graphidese, 



branched in a distinct and very elegant pedato-radiate manner, 

 wa\'y, curved and iicxnose^ the extremities very acute, immersed 

 and sunk. Disk broad, plane or concave, clothed with a grey 

 pruina, the proper margin very thin and delicate, scarcely dis- 

 cernible, flanked by the raised, prominent, broken, rugose thal- 

 lodal margins. A vertical section shows that the ascigerous disk 

 is contained in a very thin brown membranous perithecium, 

 which entirely subtends the base, and forms one of the charac- 

 teristic distinctions between this and Chiographa and Graphis 

 Smithii {O. script a, E. Bot.). 



Specimens of this in herb. Borrer ! named Opeg. dendritica 

 by Acharius himself are identical with the E. Bot. figure, though 

 the figures and descriptions in the works of Acharius agree 

 better with our var. 7. obtusa. 



13. acuta. Lirellse ramifying at a very acute angle, nearly 

 parallel, extremities simple, acuminate; thallodal margin pro- 

 minent. 



On beech. St. Leonardos Forest, Sussex ! Mr. Borrer. Upton, 

 Pembrokeshire ! Rev. T. Salwey. 



7. obtusa. Lirellce ramifying at an obtuse angle in a furcate 

 manner, extremities very obtuse, frequently fui'cate; thallodal 

 margin nearly obliterated. 



On beech. St. Leonard's Forest, Sussex ! Mr. Borrer. Tun- 

 bridge Wells ! Mr. W. Thompson. Pembrokeshire ! Rev. T. 

 Salwey. Castle Bernard Park, Bandon, Ireland ! Mr. I. Carroll. 



Plate VII. fig. 23. a, Vertical section of thallus and lirella; b, sporidium. 



4. Chiographa. 



Apothecium lirellseform or subdisciform, sessile ; perithecium 

 carbonaceous, entire or surrounding the sides and base; disk 

 plane, broad, surrounded with a proper margin and an accessory 

 thallodal margin. Thallus membranaceous. 



Name from %to>j/, snow, and fypa<^rj, writing, in allusion to 

 the white powdery thallodal margin. 



1. Chiographa L/yellii. Thallus membranous, smooth and 

 waxy, determinate ; lirellse prominent, sessile, oblong or linear- 

 oblong, simple, curved ; proper margin narrow, prominent ; thal- 

 lodal margin elevated, white, pulverulent; disk plane, broad, 

 pruinose; sporidia in asci, eight, linear, margined, rounded at 

 the ends, containing about 7-8 transversely oval margined spores. 



Opegrapha Lyellii, Sm. E. Bot. 187fi (good) (1808) ; Fries, L. Ref. 373 

 (excl.E. 15ot. 1813); Hook. Br. Fl. 2. 147 (excl. E. Bot. 1813); Schaer. 

 Spic. 323 ; Enum. 152. 



Graphis Lyellii, Ach. Syn. 85 (1814). 



