332 Rev. W. A. Leighton on new British Arthoiiiae. 



older barks the ardcllae have a wateiy stain or shading off around 

 them of a pale brown colour, especially conspicuous on spe- 

 cimens with a paler tinted thallus, and on those which are 

 whitened over with (? Leprnria alba). Disk of a rich deep brown 

 or vinous red colour, in old age becoming blackish, without 

 margin. A vertical section showed the obovate asci imbedded 

 in a dense and compact almost fleshy brown mass in which no 

 paraphyses were conspicuous. Sporidia in asci, eight, obovate, 

 colourless or of a pale yellow, margined, with a single septum, 

 the upper cell rather larger and broader than the lower one, 

 either empty or filled with com])aratively large round granules. 

 Differs from A. lurida, Ach. (Leight. Brit. Graph, p. 57. fig. 38, 

 and Leight. Licb. Brit. Exsic. 17 !), to which its general aspect 

 has some I'csemblance, in the sporidia being double the size of 

 those of that species. 



Plate XI. fig. 6. Thallus and ardellae of nat. size. Fig. 7. Whitened 

 thallus and ardellae with surrounding watery stain, nat. size. 

 Fig. 8. Thallus and ardella, magnified. Fig. 9. Vertical seetion 

 of ardella. Fig. 10. Sjjoridia, magnified. 



3. Arthonia aspei'sa, Leight. Thallus thin, membranous, 

 smooth, indeterminate, greyish-green; ardellae minute, sessile, 

 various in form ; disk black, flattened, more or less convex, 

 dull ; sporidia in asci, eight, small, obovate, 3-septate, upper cell 

 largest. 



Arthonia aspersa, Leight. Lich. Brit. Exsic. 248! (1856). 



On holly : Hobhole, Baysdale, Cleveland, Yorkshire ! Mr. W. 

 Mudd. 



Thallus very thin, spreading indeterminately, of a pale opake 

 greyish-green. ArdelUe minute, very numerous and crowded 

 as if co])iously sprinkled, distinct or confluent, very variable in 

 size and form, sometimes mere specks, roundish, oblong, ovate, 

 angular or of irregular wavy outline. Disk more or less raised, 

 convex or flattened, without any margin, ojjake black, smoothish. 

 A vertical section shows the hymenium to consist of a dark brown 

 compact mass destitute of any distinct paraphyses, with numerous 

 round or very broadly obovate asci imbedded in it. S/joridia in 

 asci, eight, obovate, pale yellow, margined, 3-septate, the upper 

 cell considerably the larger, occuj)ying nearly one-half of the 

 sporidium, the septa being confined to the lower portion. 



Differs from A. Sivartziana, Ach. (Leight. Brit. Graph, p. 54. 

 fig. 33; Leight. Lich. Brit. Exsic. 70 !), in the sporidia being 

 only half the size of those of that species and in the different 

 arrangement of the septa. 



For the two last plants I am indebted to Mr. W. Mudd of 



