528 WILD FLOWERS OF 



The yellow wall Parmelia (P.parietina), is a species 

 extremely common on walls and roofs, and no Lichen 

 abounds more upon old thorns, which it often com- 

 pletely invests as it were with coloured gloves, and 

 when, as is frequently the case, a little bright pink 

 tremelloid substance, the rose-coloured Illosporium 

 (Z roseivni) bestuds the bright orange of the Parmelia, 

 the effect produced is very beautiful. The inflated 

 Parmelia (P. pliysodes), is a very common denizen of 

 rocks, old pales, &c., whose interstices it covers as it 

 were with a profuse grey beard. 



Among the members of the genus Sticta, the Lung- 

 wort (S. pulmonaria), is very remarkable, investing 

 trees in sub-alpine countries with its large green 

 fronds, curiously pitted and reticulated, from whence 

 the name has arisen. The pitted S. scrobiculata is also 

 not uncommon among rocks, which it closely covers as 

 with an extensive glaucous-hued cloak of many folds. 



The genus Collema has thirty-three species, all of 

 a skinny or gelatinous nature, of which the Bat's- 

 wing Lichen (C. nigrescens), not uncommon on the 

 damp trunks of trees, may be adduced as a specimen. 

 These dark foliaceous and plaited substances are gene- 

 rally very obscure except in wet weather, and are, 

 no doubt, often passed by the unobservant eye. They 

 are, however, very curious, for, in fact, on the com- 

 mencement of rainy weather they spring up from 

 their unnoticed retreat like new creations. 



Peltidea almost always appears upon the ground on 

 mountains and heaths, and is easily known from its 

 size, lurid aspect above, white beneath, and its brown 

 peltate apothecia, resembling finger nails. Several 

 varieties occur, but P. canina is the most common. 



