Rev. W. A. Leightou on 7iew British Lichens. 129 



X. — New British Lichens. 

 By the Rev, W. A. Leighton, B.A., F.B.S.E. 



[With a Plate.] 



Opep'apha anomaltty Leight. Thallus thin, membranous, 

 smooth, greyish cream-coloured, limited; lirellse excessively 

 prominent and sessile, large, linear-oblong, obtuse at the extre- 

 mities, straight or wavy, simple, occasionally tripartite; disk 

 rimseform, more or less expanded; proper margins tumid and 

 eonnivent; sporidia in asci, eight, large, oblong or elliptical, 

 mai'gined, containing about nine horizontal rows of roundish 

 yellow spores. 



On holly, Glengariffe, co. Kerry, Ireland ! Mr. H. Piggot. 



Thallus a thin, membranous, scarcely subtartareous film, con- 

 tinuous, smooth and even, very slightly shining, of a pale greyish- 

 creamy colour and aspect, forming an irregular patch of small 

 extent, defined by a wavy watery brown line or margin. Lirella 

 rather numerous, dispersed without regularity over the thallus, 

 moderately large, though variable in size, stout and short, or 

 linear-oblong, very prominent and sessile, of a clear raven-black 

 and shining or even greasy-looking, either straight or slightly 

 curved, and occasionally more or less wavy, simple or occasion- 

 ally tripartitely branched, very thick and obtuse at the extremi- 

 ties, of about the same width throughout the entire length. 

 Proper margins conspicuously swollen or rounded, and eonnivent, 

 either plain, or not unfrequeutly, especially in the older lirellse, 

 marked with an irregular longitudinal interrupted furrow. 

 Disk in the younger lirellse a mere longitudinal conspicuous 

 chink or furrow, becoming wider and deeper in an older stage. 

 Peritliecium thick, carbonaceous, entire, surrounding the base 

 and sides. Paraphyses rather distinct and easily to be distin- 

 guished, though conglutinated. Asci linear-oblong. Sporidia 

 eight, large, oblong or elliptical, containing about nine hori- 

 zontal rows of rather large subrotund yellow spores. Iodine 

 turns the sporidia of a fuscate colour, slightly tinged with pale 

 blue ; on the paraphyses it has no effect. 



The sporidia are similar to those of Gr aphis scripta (Leight. 

 Brit. Graph, p. 27. tab. 6. fig. 17 b, and Leight. Lich. Brit. Exsic. 

 18 ! 19 !) and Graphis pulverulenta (Leight. Brit. Graph, p. 31. 

 tab. 6. fig. 18 6, and Leight. Lich. Brit. Exsic. 20!); but our 

 plaut differs from those lichens in the shape, relative situation, 

 and structure of the lirellse. It bears also at first sight some 

 general external resemblance to Aulacographa elegans (Leight. 

 Brit, Graph, p. 45 ; Leight. Lich. Brit. Exsic. 68 !), but the 

 erumpent lirellse, with their accessory thallodal margin, and the 



Ann. <Sf Mag. N. Hist. Ser. 2. Vol. xix. 9 



