CllYPTOGAMIA LICHENES. 103 



The Porina leioplaca of ACHARIUS (Mou&. and NEST., No. 

 847.) is surely nothing but P. pertusa in an early state, 

 but if it is to be considered a distinct and perfect species, 

 it must be added to the British list of lichens, for I have 

 gathered it in Berwickshire on the birch, and it is probably 

 far from uncommon. 



64. ENDOCARPON. 



1. E* Weberi, frond depressed, thick and somewhat leathery, 

 foliaceous, lobed ; lobes crowded, the interior irregularly convo- 

 lute, raised, the exterior undulate with rounded sinuate margins ; 

 upper surface greenish-grey, smooth, beneath fawn coloured and 

 smooth ; orifices punctiform, black, slightly raised. HOOK. Scot. 

 ii. 45, GREV. FL Edin. 329. DILL. Muse. t. 30, f. 127. 



Hab. On rocks by the sides of rivulets. On the linn in 

 Humbledon Dean above Wooler, abundant, W. C. Tre- 

 velyan, Esq. 



On drying, the colour of the upper surface becomes a greyish- 

 pink. 



65. LEPRARIA. 



1. L. flava, crust spreading, equal, thin, somewhat cracked, 

 bright yellow, composed of sub-globose granules. HOOK. Scot. ii. 

 73. Eng. Sot. t. 1350. Lichen Jiavus^ WITH. iv. 3. Byssus can- 

 delarisj LIGHTF. Scot. 1005. 



Hab. On timber long exposed to the weather ; and, with 

 LIGHTFOOT, " we have sometimes seen it cover old 

 mosses, which appear exactly as if they had been pow- 

 dered with flour of brimstone." 



2. L. latebraram, grey, pulverulent, undefined, thick ; granules 

 mixed with fibres. HOOK. Scot. ii. 73. Eng. Bot. t. 2147. (too 



areen.) 



Hab. On rocks in caverns, and on stumps of hawthorn at 

 the roots of old hedges, common. 



In caverns and in crevices this ambiguous thing " forms light 

 convex soft cushions, easily separable from the rock, their 

 central part being elevated by age, and in a manner vault- 

 ed underneath." It is thinner when growing on trees, the 



