CRYPTOGAMIA LICHENES. 87 



thecia black, convex and tubercle-like, with a bright scarlet layer 

 internally HOOK. Scot. ii. 37. WINCH, Guide, ii. 32. 

 Hab. On rocks, rare, Murton Craigs, plentiful. 



So like Lee. confluens, as only to be distinguished by the 

 bright red colour of the interior of the apothecia, a re- 

 markable character, yet relative to the validity of which 

 there is some doubt, for Mr HARRIMAN seems to have en- 

 tertained the opinion that it was the result of some disease 

 or chemical change. 



3. L. petraa) crust thin, white, cracked, subpulverulent ; apo- 

 thecia black, prominent and tubercle-like, arranged irregularly in 

 concentric circles. GREV. Fl. Edin. 324. Lichen concentricus, 

 E-ng. Bot. t. 246. 



Ilab. On rocks, in circular patches, often of considerable 

 size, not uncommon in Berwickshire. 



Best distinguished from the preceding and following species 

 by the circular arrangement of the fructification, which is 

 very striking at a little distance ; yet the name which ex- 

 presses this remarkable character has been allowed to be 

 superseded by a most unmeaning one. 



4. L. parasema, greenish-grey, granular ; apothecia black, scat- 

 tered, without gloss HOOK. Scot. ii. 37. GREV. Fl. Edin. 325. 

 t. 3. f. 1. Lichen parasemus, Eng. Bot. t. 1450. L. sanguinarius., 

 LIGHTF. Scot. 803. DILL. Muse. t. 18. f. 3. 



Hab. On trees, particularly on the ash, and on rocks, very 

 common. 



The descriptions of DILLENIUS and LIGHTFOOT agree ex- 

 actly with our plant, which is undoubtedly the Lecidea 

 elaochroma of ACHARIUS, Syn. Lich. p. 18., and ofMouGEOT 

 and NESTLER'S Stirpes Cryptogamicae^ No. 746. ; but I re- 

 tain the name adopted by British botanists, for the L. 

 nisema and elceochroma of ACHARIUS appear to be mere- 

 ifferent states of one species. Crust thin, adherent, 

 granular, somewhat cracked, greenish-grey. Apothecia 

 tubercle-like, margined, numerous. Grows in circular or 

 oval patches when unconstrained, but commonly rendered 

 more or less irregular by coming in contact with other 

 lichens, or other fronds of the same species. When grow- 

 ing separate, the border is paler than the rest of the crust ; 

 and it is curious to observe, that, whenever it conies in 



