442 Rev. W. A. Leighton on the British Graphideae. 



one half the size, of a different formation and 5-septate. Is not 

 this Acharius's A. gyrosa ? 



Plate VIII. fig. 36, Arthonia ilicina, Tayl. : a, Vertical section of ardella ; 



h, sporidia. 

 Plate VIII. fig. 37. Opegrapha atra, var. ohscura, Schaer. : a. Vertical 



section of ardella ; b, sporidium ; c, ascus with sporidia. 



7. Arthonia lurida, Ach. Thallus obsolete, smooth, pale dirty 

 brown or lead-colour, indeterminate ; ardellee sessile, irregularly 

 roundish ; disk reddish-black, slightly convex, dull ; sporidia in 

 asci eight, small, broadly obovate, uniseptate. 



Arthonia lurida, Ach. L. Univ. 143(1810); Syn. 7; Schser. Spicil. 8. 245; 



Enum. 242. t. 9. f. 6 ; Exsic. 17 '• ; Borr. E. Bot. Suppl. t. 2692. fig. 2 j 



Hook. Br. Fl. 2. 143 ; Tayl. Fl. Ilib. pt. 2. 104. 

 Spiloma paradoxum, Ach. L. Univ. 139 ; Syn. 3. 

 Coniangium vulgare. Fries, L. Europ. 378 (1831). 

 Patellaria anomala d. m. arthonioides, Wallr. Crypt. Germ. 370 (1831). 



On fir, holly and oak. Ireland ! Sir T. Gage in herb. Borrer. 

 Henfield, Black Down and elsewhere, Sussex ! Mr. Borrer. Orton 

 Wood, Leicestershire ! Rev. A. Bloxam. 



Thallus extremely thin, scarcely distinguishable, pale dirty 

 brown, on firs of a dark lead-gray hue, spreading indeterminately. 

 Ardellce numerous, either distinct or confluent, variable in size, 

 but minute, of an irregular roundish or oblong figure. Disk of 

 a dull dark reddish-black, smooth or roughish, Sporidia in asci, 

 eight ? small, broadly obovate, uniseptate, pale yellow. 



Plate VIII. fig. 38. a, Verticalsectionof thallus and ardellae; b, sporidia. 



8. Arthonia spadicea, Leight. Thallus obsolete, smooth, 

 shining, pale red-brown, indeterminate ; ardellaj sessile, variable 

 in size, larger ones roundish or oblong, smaller round and punc- 

 tiform; disk dull brownish-black, flat or tumid, smooth; sporidia 

 in asci, eight, small, slenderly clavseform, 3-septate. 



Arthonia spadicea, Leight. Lich. Brit. Exsic. 97 ! (1852). 



On the smooth bark of hazel and hawthorn, close to the 

 ground. Shelton Rough near Shrewsbury, Shropshire ! 



Thallus excessively thin, membranous, of a pale red-brown, 

 smooth, somewhat shining, spreading indeterminately over and 

 scarcely distinguishable from the smooth bark of the base of the 

 trunks which it covers close to the ground. Ardellas numerous, 

 scattered irregularly as if splashed or sprinkled, very variable in 

 size, the larger ones roundish or oblong, or by confluence irre- 

 gular in form, the smaller ones round and punctiform, of a dull 

 lurid brownish-black; in old and dry states loosening around 

 the circumference and peeling off. Disk flat or tumid, especially 



