15 

 USNEA SPHACELATA. 



Usnea spliacelata ; thallo erectiusculo fruticuliformi, ramis primariis 

 ochroleiicis nigro-vittatis laevibus, ultimis attenuatis nigris, sorediis 

 confertis concoloribus ochroleucisve. Br. (Tab. XII.) 



Usnea sphacelata. Br. in Parry's First Voy. App. p. cccvii. Hooker 

 Ace. of Arct. PI. in Linn. Trans, v. 14f. p. 384. 



Usnea? prope melaxantham. Br. Spitzb. PI. in Scoreshifs Arct. 1. 

 App. p. 76. 



Hab. In riipibus apud Spitzbergen. D. Scoreshy et Sabine. In Insula 

 Melville. D. Parry. In summitate Montis Tabularis Insula Van 

 Dieman. D. Broison. 



" Proxima U. melaxantJide Ach. Syn. p. 303, difFert statura aliquoties 

 minore, ramis primariis laevibus, sorediorum praesentia. Apo- 

 thecia nondum visa. Eandem speciem, sorediis pariter instruc- 

 tam apotheciisque destitutam, in summitate Montis Tabularis 

 Insulae Van Dieman, anno ISO^, legi." Br. 



Mr. Brown has here justly observed how closely this species 

 is allied to the South American U. melaxaiitha. Indeed, that 

 lichen which I have described as the U. inelaxantha in Hum- 

 boldt and Kunth's Syriopsis, and which is found at an eleva- 

 tion of more than 10,000 feet upon the Andes, differs in no 

 respect from the present plant, except in having the base of 

 the thallus of a reddish yellow, and the extremities of the 

 branches more black. Mr. Brown further mentions that he 

 has found U. sphacelata also', but destitute of fructification, 

 upon Table Mountain, in Van Dieman's Island. From a neigh- 

 bouring country, New Holland, I have received the c(|ually 

 nearly allied species, U.fasciata, and in a very fine state of 

 fructification, differing in no respect from the antarctic spe- 

 cimens. These latter approach the U. sphacelata in their 

 pale yellowish hue, the U. melaxantha in the more crowded 

 ramification, and hispid or tuberculatcd thallus ; and differ 



