CRYPTOGAMIA LICHENES. 81 



4. P. stellaris) stellated, ash-grey, beneath whitish with black 

 fibres ; segments linear, smooth, rather convex, multifid ; shields 

 hoary, black, with a grey inflexed border. HOOK. Scot. ii. 55. 

 Lichen stellaris, LIGHTF. Scot. 824. WITH. iv. 32. Eng. Rot. 

 t. 1697. DILL. Muse. t. 24. f. 70. 



Hob. On the trunks of trees, not uncommon. 



"It forms roundish patches conspicuous for their neat radia- 

 ting figure, and their bright silver-grey hue, which is near- 

 ly the same whether wet or dry, and never assumes any 

 tinge of green." The figure in Eng. Bot. is very faulty in 

 respect of colouring : and that of DILLENIUS is scarcely 

 worth quoting. 



* * Under surface darker coloured than the upper. 



5. P. pulverulenta, imbricated, stellated, deep glaucous green, 

 ash-grey when dry ; segments lobed, plane, obtuse, beneath black 

 and fibrilose ; shields black, hoary, with a thick inflexed border. 

 'HooK. Scot. ii. 55. L. stellaris /S. LIGHTF. Scot. 824. Lichen 

 f/ubterubntnt) Eng. Bot- 1. 2003. 



Ilab. On the trunks of old ash-trees in large circular patch- 

 es, often becoming irregular. 



The frond is more or less uneven. The shields are nume- 

 rous and pressed against one another, at first hoary, but 

 this disappears, and they are then brownish-black. The 

 border is thick, and " as it advances in age, acquires a 

 scaly, and often leafy, circumference." 



6. /'. sa.ratitta, imbricated, bluish-grey ; segments irregularly 

 t'ut and crenate, pitted, rough, beneath black, hirsute ; shields 

 deep reddish-brown with a granular border. HOOK. Scot.-u. 53. 

 Lkhrn swatiiif, LIGHTF. Scot. 816. WITH, iv, 36. Eng. Bot. 

 t. 603. DILL. Muse. t. 24. f. 83. 



Hah. On trunks of ash-trees, and on large stones and rocks, 

 common. 



The fronds spread circularly in a rugged imbricated manner. 

 Those on trees are of a bluer colour than those on stones. 

 The former we have not observed in fruit, the latter fre- 

 quently, but they are then generally rough all over with 

 small farinaceous tubercles. "The shields are large, cupped 



D 3 



