LICHENS. 167 



rived at the conclusion that at least all the British Eamalinae are 

 only varying forms of one species. This species has a very wide 

 geographical range, being found on the Himalayas, and in differ- 

 ent parts of India, in Lapland, and in the polar regions, in North 

 America, and it is said to contain a considerable amount of gum, 

 which has been used instead of gum arabic in calico printing and 

 in tho making of parchment and pasteboard ; in a pulverised form 

 it has been used as the basis of hair powders. (" Lindsay's 

 British Lichens.") 



(4) Parmelia seems to be derived from parma, a round buckler, 

 in allusion to the appearance of the apothecia, or the horny disks 

 arising from the thallus, and containing the spores. This is one 

 of the largest and most extensive genera of lichens, and its species 

 are very widely distributed in all parts of the world, being found 

 even " on all the rocks projecting through snow, without any 

 limitation as to height, and ascending far above the snow-line : 

 they also occur at above 16,000 feet on Chimborazo." The forms 

 or species of Parmelia so common in Europe, are found in 

 similar situations here, namely on rocks, old trees and fences. 

 P. caperata, P. pulverulcnta, and P. stellaris, generally occur on 

 trees and fences, and P. saxatalis and P. olivacca on rocks in or 

 near creeks ; but as in Europe, so also here, the last-mentioned 

 species is sterile and degenerate when in such localities, and it 

 appears to afford an instance, similar to that already adverted to 

 in some mosses, of increasing and spreading without fructification. 

 These lichens appear as white, grey , greenish, or olive coloured 

 patches, and they are very abundant oil trees, (particularly 

 Casuarina, &c.), when growing in shady places near creeks, in- 

 creasing apparently in size and beauty, as the trees become old 

 and decayed. In the Pharmacopeia, P. caperata, P. olivacea, and 

 P. saxatalis, are mentioned as " roborant" and " astringent," and 

 it is stated that in some parts of the world, they are used in dye- 

 ing, but in " Lindley's Medical and Economical Botany," the 

 only species retained is P. parietina, or as it is called in Europe 

 the Yellow Wall Lichen, which is said to be bitter, and yielding a 

 yellow colouring matter. I have noticed this species near Parra- 

 matta, but it grows on sandstone rocks near the coast. On some 

 of the inland species, I have seen some minute species of 

 Jungermannia, but not ditlering materially from those described 

 as European. 



