USNEA. 41 



age ; pale yellow and becoming darker, the more or less attenu- 

 ate tips blackening, or black-vittate j apothecia, in South Ameri- 

 can specimens, sub-terminal, appendiculate ; disk black; fibres 

 of the margin commonly obsolete. Spores rounded-ellipsoid, ^- 



mic. Th. Fr. Licli. Spitsb. p. 9. U. melaxantha, Ach. L. U. 



p. 618. Neuropogon, Nyl. Syn. 1, p. 272. Usnea sphacelata, 

 E. Br. 



Kocks, Arctic America ; dwarfed, and sterile. Melville Island 

 (Parry's 2d Voy.), E. Brown, 1824 5 Babington. Greenland,/. 

 Vahl. The modification of the medullary cord is now marked in 

 the luxuriant austral lichen ; but scarcely to be detected in the 

 Arctic specimens, whether American or European. 



* * Medullary cord continuous. Disk of apothecium pale. 



" 2. U. barbata (L.) Fr. ; thallus terete, papillate-scabrous 



glaucescent. Spores rounded-ellipsoid, -JJ mic. Fr. L. E. p. 



18. Schcer. Spicll. p. 504. Nyl. Syn. I, p. 267. 



f a. florida, Fr. ; thallus tufted, erect, stout and rigid, diva- 

 ricately branched, more or less strigose-fibrillose; apothecia 

 (abundant) middling to large, pale-flesh-coloured, with now a 

 white bloom. 



* hirta, Fr. ; very minutely more or less fibrillose, and be- 

 sprinkled thickly with soredia. 



* * rub-iginea, Michx. j similar to the last, but rusty-red. 



b. ceratina, Schser. ; thallus as in a, but pendulous and finally 

 much elongated ; the apothecia middling to large, rarer in ex- 

 treme (mountain) forms, which pass into c. 



c. dasypoga, Fr. ; thallus pendulous, slender and rather lax, 

 much-elongated ; rather sparingly divided, the branches beset 

 with spreading fibrils ; apothecia smaller, and less frequent. 



d. plicata, Fr. ; thallus pendulous and much elongated, slen- 

 der and lax, sub-dichotomously divided, pale, the branches with- 

 out spreading fibrils ; apothecia smaller and less frequent. 



e. articulata, Ach. ; thallus pendulous, broken more or less 

 into joints, and the joints inflated; apothecia not seen. 



Very common on trees, and (mostly degenerate) on dead 

 wood, and stones, throughout the United States and Canada 

 (Muhlenberg Catal. 1818), and far northward (Richardson) ; a, 



