Opegrapha.] LTCHENES. H3 



with regard to its apothecia, what Collema is to the foliaceous 

 Lichens, as respects the thallus. All are found on the bark of 

 trees. 



1. A. impolite, Borr. (pruinose Arthonia); crust somewhat 

 tartareous thin cracked uneven white, apothecia immersed 

 flat confluent brownish lead-coloured pruinose. Borr. in E. Bot. 

 ,s,, r pf.f.2692.f. 1. — Arthonia pruinosa, Ach. Lich. Uhiv.p. 147. 

 t. \.f 3. it Syn. p. 7. — Lichen impolitus, Ehrh. Cr. {not E. Bot. 

 which is probably taken from a common appearance of Spiloma 

 gregarium, — S. twnidulvm, Ach., — of which a more perfect state is 

 represented at t. '2151. Borr.)^~Verrucaria impolita, Hoffm — 

 Parmelia impo/ita, Ach. Meth. 



Frequent on boarded buildings and on the rugged bark of old oaks. 



2. A. lurida, Ach. (lurid Arthonia); crust obsolete continu- 

 ous smooth dull lead-coloured or brownish, apothecia sessile 

 roundish slightly convex reddish-black. Borr. in E. Bot. 

 Suppl. t. 2692. f. 2. Ach. Syn. p. 7 — Spiloma paradoxum, Ach. 

 Syn. t. 3. 



Probably not rare on bark, in shady places. On Holly and Oaks, 

 Sussex, Mr. Borrer. Fir-trees in Ireland, Sir Thomas Gage.— 1 he 

 crust of this is so thin, that Mr. Borrer questions whether it is anything 

 more in reality than a discolouration of the bark, and whether it has a 

 just claim to rank among the Lichens. The synonym of Achanus Mr. 

 Borrer has given upon the authority of original specimens in the Museum 

 of the Linnaean Society. 



3. A. Swartzidna, Ach. (Swartzian Arthonia); crust thin 

 cartilagineo-membranaceous cracked cream-coloured, apothecia 

 roundish repand wavy and depressed uneven sometimes con- 

 fluent. Ach. in Schrad. N. Joum. v. 1. fasc. 3. p. 13. t.4.f. 1, 

 ,i Syn. p. 5. E. Bot. t. 2079. 



On the smooth bark of trees, Sussex. Mr. Borrer.— h is upon this 

 species that the genus Arthonia was founded byAeharius. Other Lichens, 

 which he lias referred to it, should be separated from it, in the opinion ot 

 other Botanists. I have followed Mr. Boner's suggestion in removing 

 Arthonia lyncea of Ach. to Opegrapha. The A. astroidea of Achanus, 

 Mr. Borrer thinks is too nearly allied to this; but the species so called 

 in A'. Bot. he suspects rather to belong to Opegrapha atra. 



4. Oim'oi: \ imi a. . \eh. < tpegrapha. 



Tludhis crustaceous, membranaceous or Leprose, spreading, ad- 

 nate, uniform. Apothecia dm lb, > elongated, simple or branch- 

 ed, sessile or immersed, the dish narrow with a proper border 

 and sometimes with an additional our derived from the thallus, 



— Named from off* hollow, and '^/-'■•- Writing: from il> curious 



/,/,//„ resembling inscribed characters.— The character of this 

 genus depends upon the elongated apothecia or Ureiia*, with a 

 raised proper border ; and Mi-. Borrer, whose arrangement and 

 synonyms of the spe< :ies, obligingly communicated to me, I en- 

 tirely follow, includes aUothrc//w/>.W..v,,f Aohnrios;oensideving 



