The range of this Lichen is very wide. It is found in the Arctic regions of both the New and Old World; on the Andes under the Equator, at an elevation of 11,000 feet; on the mountains of Tasmania at 3,000 and 4,000 feet; in Chili, the Falkland Islands, Fuegia, and the New South Shetlands. Now it is worthy of notice, that in none of the Arctic, the equatorial, or south temperate latitudes, does this plant produce apothecia ; and that in the Antarctic, where alone apothecia have hitherto been found, these are always barren. Further it is remarkable, that this Lichen grows only where no other Usiiea is found in fruit; and is, perhaps, the only species of that genus which universally inhabits rocks; circumstances which, taken together with its increasing in luxuriance with the exposure it is subjected to, suggests the possibility of its being a state of some other species of this highly variable and universally diffused genus, and that, distinct as the Antarctic specimens of U. melaxantha appear, they may owe their characters to the climate, for there is very great difficulty in defining the species so as to exclude states of U.florida. Tn South Chili, where the U.florida commences (proceeding southwards), we have specimens of U. ceruchia, Mont., which are, perhaps, states of U. melaxantha. Again, in Tasmania I am unable to distinguish some specimens of U. barbata and U.florida (?), which grow on the trunks of dead trees in the higher parts of the island, from the U. melaxantha of the summit of Mount Wellington and other elevated mountains.
2. Usnea Taglori, Hook, fil.; thallo erecto lsevi pallide citrino dichotomo, ramis erectis gemmis papulosis sparsis, apotheciis tenninalibus majoribus demum planiuscuUs, disco atro, margine integerrimo, dorso laevigata. Lond. Journ. Bot. vol. iii. p. 657. (Tab. CXCV. Fig. I.)
Hab. Kerguelen's Land ; on rocks from 100 to 1,200 feet of elevation : very abundant.
U. melaxantha simillima, differt prascipue thallo lsevi polito et colore leetiore nitente.
So closely allied to the U. melaxantha, that I advance this species with much hesitation. None of the Kerguelen's Land specimens exactly tally with any of its congeners from other Antarctic localities, but approach them very nearly indeed ; so much so, that the present should be perhaps regarded as a permanent variety only. If it be so, it is singular that it is the only one in which asei have hitherto been detected ; these are abundant in all the apothecia, and vary much in size, in the form of their contained spores, and in the arrangement or grouping of these, as shown in the accompanying plate.
This is by far the most handsome vegetable production of Kerguelen's Land.
Plate CXCV. Fig. I. — 1, young, and 2, full grown plants of the natural size ; 3, vertical section of young and 4, of old apothecium ; 5, lamina proligera, with asei and spores :— very highly magnified.
3. Usnea barlata, Ach.; Lick. Univ. p. 624. Fl. Antarct. Pt. 1. p. 194.
Var. c. articidaia, Ach.; Syn. Metli. p. 306.
Hab. Herrnite Island, Cape Horn, and the Falkland Islands; abundant on the stems of Empetrum and in heathy and rocky places. Var c. Falkland Islands, Mr. Wright. Herrnite Island, Cape Horn ; top of Mount Foster and Kater's Peak, &c.
Also a native of Lord Auckland's group, Campbell's Island, and Tasmania. In Europe it is found as far north as Lapland.
4. Usnea plicata, Ach.; Licit. Univ. p. 622. Fl. Antarct. Pt. 1. p. 194.
Hab. Falkland Islands, and Herrnite Island, Cape Horn; on twigs of bushes, &c. Strait of Magalhaens, Jacqitinot.
A more Arctic and Antarctic plant than the following, reaching Cape Horn in 57° S., and the shores of the Polar Sea in Arctic America, or 69° N., beyond which it is succeeded by the U. melaxantJia in both extremities of the globe.
