GYROPHORA. 



a smoky brown-colour, lobed and erose at the margin, beneath sub- 

 fibrillose and paler. Shields rather convex, variously plaited. — This 

 and the following constitute a part of the Tripe de Roche, on which 

 travellers in the Arctic regions of America have been forced to live in 

 cases of emergency. It is nutritious ; but mixed with a disagreeable 

 bitterness, and productive of severe colic, and other distressing local 

 complaints. 



1334. G. cylindrica Ach. syn. 65. Hooker B. F. ii. 218. — 

 Umbilicaria crinita Hoff. Lich. t. 44-. {Dill. muse. t. 29. f. 116.) 

 — Common on mountain rocks. 



Thallus coriaceous, simple, or many-leaved, slightly wrinkled, dark 

 bluish or greenish-grey, variously lobed and plaited, coarsely ciliated at 

 the margin, with black branched wiry bristles, beneath smooth, pale, 

 with scattered branching fibres. Shields elevated, nearly plane, vari- 

 ously plaited. 



CETRARIA. 



Thallus foliaceous, cartilagineo-membranaceous, ascending 

 and spreading, lobed and laciniated, on each side smooth and 

 naked. Shields orbicular, obliquely adnate with the margin of 

 the thallus, the lower portion being free, (not united with the 

 thallus ;) the disk coloured, plano-concave, with a border formed 

 of the thallus and inflexed. 



1335. C. islandica Ach. syn. 229. Hook. B. F. ii. 221.— 

 Lichen islandicus E. Bot. t. J 330. Woodv. t. 265. — On the 

 ground in exposed situations in northern countries. (Iceland 

 Moss.) 



Thallus erect, tufted, olive-brown, paler on one side, laciniated, chan- 

 nelled and dentato-ciliate, the fertile lacinias very broad. Shields brown, 

 appressed, flat, with an elevated border. — Notwithstanding the presence 

 of so large a quantity of bitter principle in this, that Sir John Franklin 

 and his party could hardly eat it, although in a state approaching star- 

 vation, it is a favourite substance with some practitioners in affections 

 of the pulmonary and digestive organs, particularly in phthisis, chronic 

 catarrh, dyspepsia and chronic dysentery. It is frequently given to sick 

 persons as an alimentary substance, the bitter having been first removed 

 by washing in a weak alkaline solution. The aqueous decoction, if 

 made sufficiently strong, forms a jelly when cold ; when flavoured with 

 a little white wine it is an exceedingly pleasant diet. Pereira. 



1336. C. nivalis Ach. syn. 228. Hooker B.F. ii. 221.— 

 Lichen nivalis Eng. Bot. t. 1994. — Mountains in northern 

 countries. 



Thallus pale sulphur-coloured, orange at the base, erect, tufted, 

 nearly plane, pitted and reticulated, laciniated, its segments multifid, 

 crisped, crenato-dentate, divaricated, often waited at the point. Shields 

 pale flesh-colour, their border crenulated. — Has similar properties 

 to the last. 



BORRERA. 

 Thallus cartilaginous, branched and laciniated, the segments 

 free, generally grooved beneath, the margins frequently ciliated. 

 627 s s 2 



