79 



NEW BEITISH LICHEN. 



By Dr. J. Stirton. 



Pazmelia Millaniana. Sp. nov. — Tlialliis tenuis pallide virescens 

 (K flavens, C flavens) vel pallide glaucescens laciniato-lobatus, 

 laciniis sinuato-incisis sa?pe imbricatis, la^vis vel subl^vis laxe ad- 

 fixus, strato mednllari tenui pallide flaventi (Cflavo), subtus niger, 

 ambitu spadiceus, rhizinosus, rhizinis nigris confertis plerumque 

 dendritico — et divaricate — ramosis ; apotliecia ignota. 



Supra Hypnum cupressiforme socia Parmelia^ pbysodis. 



Tbis Parmelia is peculiar, inasmuch as C produces on the 

 yellowish medulla a decided and permanent yellow ; while K does 

 not produce any visible reaction, altliough C applied thereafter 

 gives a permanent orange. The rbizinaj in the specimen are truly 

 of the dendritic character, as the branches are numerous, and arise 

 abruptly from a common stock. This character is of less im- 

 portance than the other, as the place of growth is known to in- 

 fluence considerably the prevalence and habit of these radicles. 



Thallus thin, albido-glaucescent (K yellow, C yellow), laciniato- 

 lobate, lacinia?, sinuato- incised, often imbricated, smooth, laxly 

 affixed; medulla pale yellow, thin (C yellow); under surface 

 black, towards the margin brown, with black branching radicles ; 

 apothecia unknown. 



This lichen resembles in several aspects P. laevigata (Sm.). 

 Discovered by the Eev. Dr. MacMillan, of Glasgow, in Glen Crow, 

 at tbe head of Loch Long, during the summer of this year. 



Lecidea emphysa (Strn.), described in the No. of " Grevillea" 

 immediately preceding this == Arthonia luricla (Ach.). 



I was induced to rank this lichen with the Lecidece from the 

 fact that after the chrysophanic acid, which it contained in abun- 

 dance, had been dissolved and made to disappear by means of liq. 

 potassje, the paraphyses were rendered tolerably distinct, as well as 

 the spores, which^ in much the larger proportion, were of a fusces- 

 cent tint. It is curious, also, that if a solution of iodine be 

 applied after the action of liq. potassae, a coerulescent tint is com- 

 municated to the hymenium, instead of the deep vinous red, the 

 usual reaction. 



It must be confessed that A. hirida has neither in the shape of 

 its spores, external conformation, &c., almost any analogy to 

 the typical Arthonia ; the same may be said of A. mediella (Nyl.), 

 which, by the way, I have also secured near Grantown, and in 

 "connection with which I may take another occasion of making a 

 few remarks. 



