Rev. W. A. Leighton on tlie British GraphidciE. 441 



Udlington near Shrewsbury, Shropshire ! On elra, Batchcot, 

 Hey Forest near Ludlow, Shropshire ! 



Thallus thin, tartareous, cracked and uneven, somewhat pow- 

 dery, whitish or pale yellow, spreading indeterminately over the 

 rugged bark of trees. Ardellce very numerous and crowded, 

 covering nearly the whole thallus, and giving it at a little 

 distance a blackish pruinose aspect, very variable in size and 

 shape, roundish or irregularly oblong, or otherwise deformed by 

 conHuence, immersed, flat or slightly convex, brownish when 

 the pruina is rubbed off, otherwise of a lead-colour, minutely 

 roughened on the surface, which is covered with a white pruina ; 

 in section pale and semitransparent, subgelatinous, enclosing 

 the asci which contain eight sporidia, of an obovate-linear or cla- 

 vate form, rounded at the extremity, generally 4-septate, some- 

 times 5-septate, and sometimes only 3-septate, pale yellow. 



Plate VIII. fig. 35. «, Section of thallus and ardella ; b, sporidia; c, ascus 

 with sporidia. 



6. Arthonia ilicina, Tayl. Thallus thin, membranous, smooth, 

 shining, scaly, cream-colour, limited ; ardellse subimmersed, 

 scattered, in-egularly rounded or oblong ; disk brownish-black, 

 plane, shining ; sporidia in asci, eight, very large, obovato-clavate, 

 6-septate, upper cell largest. 



Arthonia ilicina, Tayl. Fl. Hib. p. 2. 105 (1836). 



On holly. Cromeglown, Ireland ! Dr. Taylor in herb. Borrer, 

 Glengariff, Ireland ! Miss Hutchins in herb. Borrer. New Forest, 

 Hants ! Mr. Lyell in herb. Borrer. St. Leonard's Forest, Sussex ! 

 Mr. Borrer. 



Thallus thin, membranous, smooth, somewhat shining, scaly, pale 

 yellow or cream-colour, forming irregular patches 3-4 inches in 

 diameter, limited by an indistinct irregular brown wavy watery 

 border variable in width. Ardellce numerous, scattered, of a 

 large size, but with smaller ones interspersed, irregularly rounded 

 or oblong, their outline' entire or slightly wavy, half immersed 

 in the thallus, when dry flat, often cracked, curving up at the 

 margin as it were in loosening themselves from the thallus, 

 when wet convex and prominent. Disk plane, of a full brow^nish- 

 black, slightly shining. Lamina proligera pale brown, darker 

 brown on the surface, enclosing asci, each containing eight large 

 sporidia, obovato-clavate, 6-septate, the uppermost cell very 

 remarkably the largest. 



Opegrapha atra, var. obscura, Schser. Exsic. 517 ! is similar in 

 colour and general appearance, but the ardellse are smaller, closer 

 together and arranged in irregular parallelism, their outline 

 crenato-incised, their surface somewhat wrinkled, the sporidia 



