ya CRYPTOGAMIA LICHENES. 



lets. It is smooth, somewhat glossy, and of a light or 

 chestnut-brown, about 2 inches in height. When moist, 

 the stem, as WAHLENBERG remarks, is tough, so that it 

 tears, and will not break. Sph. fragile, on the contrary, is 

 a smaller plant, of a greyish colour, without any gloss, and 

 the stem is not distinguishable from the branches, the 

 whole constituting a dichotomously branched frond. It is 

 very fragile, and much resembles a coralline. 



55. B^OMYCES. 



1 . B. rufus, crust spreading, greenish-grey, uneven, granular ; 

 apothecia on whitish somewhat compressed short stalks, small, 

 reddish-brown, smooth, convex HOOK. Scot. ii. 65. LicJien 

 byssoides, LIGHTF. Scot. 809. Eng. Bot. t. 373. Patellaria rufa, 

 SPRENG. Syst. Veg. iv. 269. DILL. Muse. t. xiv. f. 5, 



Hab. On gravelly banks in heathy places. Road-side near 

 Houndwood Inn, with Polytrichum aloides, abundant, 

 producing its fruit in early spring. 



56. ISIDIUM. 



1. /. corallinum, " crust tartareous, at length cracking, greyish- 

 white ; podetia minute, varying in length, cylindrical, smooth, 

 simple or branched, disk of the fructification brownish-grey." 

 GREV. Fl Edin. 346. t, iii. f. 15, HOOK. Scot. ii. 66. Lichen 

 corallinus, LIGHTF. Scot. 808. WITH. iv. 17. 



Hab. Rocks in heaths. Humbleton Dean, near Wooler, 

 James Mitchell, Esq. R. N. Murton Craigs, plentiful. 



Without a close examination this may be overlooked as the 

 crust merely of Lecanora tartarea. LIGHTFOOT'S descrip- 

 tion is excellent. " At first view this appears to be only 

 a white tartareous crust, about |th of an inch thick, with 

 an unequal surface, formed into knobs or buttons ; but 

 being broken and examined with a microscope, it is found 

 to consist of compact bundles of short, round, stony, 

 branched, coral-like fibres, the branches all obtuse and 

 even at the top, without tubercles." In this country it is 

 always of a grey colour ; but, according to Dr CLARKE, in 

 Scandinavia, the gradations of colour, from white to brown, 

 black, and red, are very remarkable; and sometimes all 

 these gradations might be observed upon the same speci- 

 men. The red colour was alwavs the most vivid where 



