200 LICHENES. [Parmelia. 



the preceding species are liable to be infested with a parasite, which has 

 been called Endocarpon parasiticum Ach. (E. Bot. t. I860.) 



8. P. perforata, Ach. (perforate-shielded Parmelia); thallus 

 orbicular somewhat membranous glaucous-green naked deeply 

 lobed crenate and sinuated fringed with black hairs at the 

 margin black and rough beneath, apothecia red-brown at length 

 perforated deep and concave with an entire narrow border. — 

 Ach. Syn. p. 198. — Lichen perforates, Ach. Prodr. — E. Bot. 

 t. 2423 — Dill. Muse. t. 20. f. 42, 43 and 44, and t. 82. /. 3. 



On rocks and old trees, Wales, Sit. J. E. Smith. Sussex, not unfre- 

 quent, Mr. Boner. — The fructification has never been found in Britain. 

 In America and other countries this plant is abundant, and I have lately 

 received copious specimens with their curious apothecia, gathered by Mr. 

 Drummond on the Missouri. 



9. V.perldta, Ach. (pearly Parmelia); thallus orbicular glau- 

 cous with rounded sinuated and crenate flattish lobes often bor- 

 dered with powdery tubercles black and hairy beneath, 

 apothecia elevated olive-coloured concave with a crenate thin 

 powdery inflexed border. — Ach. Syn. p. 197. — Lichen perlatns, 

 Linn.—E. Bot. t. 341.— Dill. Muse. t. 30./. 39. 



Trunks of old trees and pales, not unfrequent, but very rare in fruc- 

 tification. — Sir J. E. Smith has translated perlatus by pearly -, but the 

 word was probably intended to imply its wide-spreading habit. 



10. P. laevigata, Ach. (even grey Parmelia); thallus spread- 

 ing greyish-white smooth deeply cut into many multifid lobes 

 and segments the ultimate ones broadly linear acute with ter- 

 minal powdery warts black and shaggy beneath, apothecia very 

 concave deep chestnut with an entire inflexed border. — Ach. 

 Syn. p. 212. — Lichen Icevigatus, E~ Bot. t. 1852. 



On rocks, Anglesea and Caernarvonshire, Rev. H. Davies. 



11. P. herbdcea, Ach. (bright-green Parmelia); thallus orbicu- 

 lar membranaceous bright-green and naked above when moist 

 (whitish-brown when dry) lobed and crenated at the margin 

 whitish dow r ny and fibrous beneath, apothecia orange-brown nearly 

 flat with an inflexed border. — Ach. Syn. p. 298. — Lichen l&te- 

 virens, Lightf. — Dichs.— E. Bot. t. 294. 



On the trunks of trees, decayed wood, rocks and mosses, in mountain- 

 ous countries. — A large and very handsome species, often forming broad 

 conspicuous patches on the trunks of trees in moist subalpine regions. 



12. P. tilidcea, Ach. (smooth grey Parmelia) ; thallus orbicular 

 membranaceous pale glaucous-grey subpruinose lobed and sinu-. 

 ated crenate shaggy and brownish-black beneath, apothecia 

 brown with an incurved entire or crenate border. — Ach. Syn. 

 p. 299.— Lichen tiliaceus, Hoffm.—E. Bot. t. 700. 



On trees, in the south of England. On rocks, Anglesea and Caer- 

 narvonshire, Rev. H. Davies. Upon the battlements of Brodick Castle, 

 Isle of Arran, 



13. V.olivdcea, Ach. (olive-coloured Parmelia); thallus orbicu- 



