84 CliYPTOGAMIA LICH ENES. 



vex. HOOK. Scot. ii. 47. Lichen subfuscus, LIGHTF. Scot. 8K. 

 WITH, iv. 22. Eng. Bot. t. 2109. DILL. Muse. t. 18. f. 16. 



Ilab. On trees, gate posts, and on rocks, very common. 



A species subject to much variety in the size of its apothecia, 

 and in their shade of brown. It grows in oval or unde- 

 fined patches, closely adherent, and thickly studded over 

 with the fructification. 



3. L. ventosa, crust granulated, warty, thick, yellowish-grey ; 

 apothecia deep reddish-brown or brownish-red, plane becoming 

 convex, with a waved entire border HOOK. Scot. ii. 48. Lichen 

 ven^is, LIGHTF. Scot. 806. WITH. iv. 16. Eng. Bot. t. 906. 

 Patellaria ventosa, SPIIENG. Syst. Veg. iv. 266. 



Hab. Rocks on mountains. Cockburn Law. 



The apothecia are but slightly elevated above the crust, or 

 even with it. They eventually rise above and conceal the 

 narrow border. 



4. L. perettusj crust granulated, rather thick, white ; apothecia 

 of the same colour, wart-like, concave, with a thick rounded bor- 

 der HOOK. Scot. ii. 48, Lichen parellus, LIGHTF. Scot. 814. 

 WITH. iv. 17. Eng. Bot. t. 727. 



Ilab. On rocks by the sea side, on stone walls, and on ash 

 trees, common. 



So abundant in this neighbourhood, that many of our stone 

 dikes are whitened with its circular crusts. On the sand- 

 stone rocks at Hudshead it is remarkably fine,. the circles 

 there attaining such a size as to measure a foot in diameter. 

 Crust adherent, coarsely granular, thickly studded with 

 wart-like apothecia of the same colour as the crust, often 

 granular in the disk, and surrounded with a thick raised 

 border. When an apothecia is cut the centre appears of a 

 flesh colour. The margin of the frond often assumes a 

 brick -red colour. From this species the finest litmus is 

 prepared ; slips of unsized paper stained with which, are 

 well known to chemists as delicate tests for ascertaining 

 the presence of minute portions of uncombined acids. 

 NEILL. 



r u L. tartarea, crust greyish-white, thick, coarsely granular, 

 uneven, cracked ; apothecia saucer-like, becoming large and irre- 



