PARMELIA. 65 



less regularly divided, convex ; beneath channelled, or the mar- 

 gins connivent, and densely, or now obsoletely fibrillose ; apo- 



thecia unknown. L. U.p.492; Syn. 211, auct. Nyl. Syn. 1, 



p. 393. P. chlorochroa, Tucker m. Obs. Lich. 1, 1. c. p. 383. 



On the earth, in sterile spots, in the Rocky Mountains (Dr. 



Hayden), Tuckerman 1. c. I860. The same lichen is found in 



Soongaria (Herb. Spreng. nom. Borr. Camtschadatts), in Camts- 

 chatka (Tilesius in herb. Floerk., nom. Farm, congruentis), and in 

 the steppes of the Volga in Russia (Herb. Krempelh., nom. P. 

 vagantis, Nyl). The last-cited plant of Ny lander is the P. 

 molliuscula, v. vagans of his Syn. I. c., which is later subsumed 

 by him under P. conspersa (Scand. p. 100) and is the natural key 

 to the present. In a very narrow-lobed, fertile form of P. con- 

 spersa (rocks, Kansas, Hall), sufficiently agreeing in general 

 habit with Fellmann exs. n. 79, and with the narrower form of 

 Anz. Lich. Ital. Sup. n. 109, and, like them, referable to the 

 v. stenophylla of authors, the lobes are not only convex, as, to 

 some extent, in the Italian lichen last cited, but more or less 

 channelled beneath; and the same convexity and channelling 

 are observable in dwarfed, alpine specimens of the same species, 

 growing over mosses (Rocky Mountains, Dr. Parry) and suffici- 

 ently explain the lichen before us. 



17. P. centrifuga (L.) Ach.; thallus somewhat tartareous, 

 many-cleft, from greenish- at length bright-straw-coloured, 

 opake ; beneath whitish with darker fibrils ; lobes linear, convex, 

 crowded, becoming complicate and rugose-plicate at the crust- 

 like centre, which falling finally away leaves only the concentri- 

 cally disposed periphery ; apothecia middling-sized ; disk chest- 

 nut, with a sub-crenulate margin. Spores ellipsoid, -^ mic. 



Ach. L. U. p. 486. Fr. L. E. p. 71. Tuckerm. Lich. Amer. 

 n. 78. Nijl. Syn. 1, p. 393. 



Alpine and sub-alpine rocks, and descending, in high moun- 

 tains, Muhlenberg Catal 1818. Arctic America, Vahl, etc 

 Newfoundland, Despreaux, etc. Mt. Desert, Me., and White 

 Mountains, N. H., Tuckerman. North shore of Lake Superior, 

 Agassiz. 



18. P. incurva (Pers.) Fr. ; thallus sub-cartilagineous, many- 

 cleft, greenish-straw-coloured, opake, besprinkled with large, 

 globular, sulphur-coloured soredia; beneath pale, with blacken- 

 ing fibrils ; lobes very narrow, teretish, densely branching, and 



5 



