Acta Societatis pro Fauna et Flora Fennica, 53, N:o 1. 295 



9. Rh. concentricum (Dav.) Vain. 



Lichen concentricus Dav. Trans. Linn. Soc. II (1794) p. 284. 

 Lichen calcarius Weis PI. Crypt. Getting. (1770) p. 40 (haud L. Sp. 

 PL II, 1753, p. 1140). Rh. calcareum Th. Fr. Lich. Scand. II (1874) 

 p. 631. 



Thallus crustaceus, uniformis, continuus aut rimosus 

 vel areolato-diffractus, laevigatus aut verrucoso-inaequalis, 

 albus aut cinerascens, nee KHO, nee jodo reagens, hypo- 

 thallo nigrieante aut indistineto. Apothecia thallo immersa, 

 vulgo mediocria, disco piano, nigro, nudo, haud papillate, 

 margine modiee incrassato aut sat tenui, subpersistente, 

 nudo aut pruinoso. Epitheeium olivaceum aut subfuseeseens. 

 Sporae 8:nae, deeoloratae aut demum leviter obscuratae, 

 „long. 0.022 — 0.045, crass. O.oio — O.021 mm" (see. Arn, et Th. Fr.), 

 demum murali-divisae, cellulis haud numerosis. 



F. subconcentrica (Fr.) Vain. Lecidea atroalba e. subconcentrica 

 Fr. Lich. Eur. Ref. (1831) p. 313. Rh. petraeum d. sab concentricum 

 Koerb. Syst. Lich. Germ. (1855) p. 260. Rh. subconcentricum Koerb. 

 Parerg. Lich. 3 Lief. (1861) p. 232. Lichen concentricus Dav. 1. c. Rh. 

 concentricum Beltr. Gas. Lich. Bassan. (1858) p. 187; Arn. Lich. Frank. 

 Jur. (Fl. 1884) p. 199 (573), Lich. Miinch. (1891) p. 94; Flag. Fl. Lich. 

 Franche-Comte II (1894) p. 499. L. petraea *L. concentrica Nyl. Lich. 

 Scand. (1861) p. 234. L. excentrica f. concentrica Nyl. Lich. Paris (1896) 

 p. 101. Rh. petraeum Mass. Ric. Lich. Crest. (1852) p. 102 (haud 

 L. pctraeus Wulf. Winterb., 1788, p. 89 sec. Arn. Zur Erinn. Wulf. 

 p. 157). 



Exs. Leight. Lich. Brit. Exs. I (1851) n. 17. — Rabenh. Lich. Eur. 

 Exs. IV (1856) n. 109. 



Thallus tenuis aut modiee incrassatus, uniformis, cinerascens 

 aut sordide albidus, hypothallo indistineto aut leviter evoluto nigri- 

 canteque. Apothecia p. p. in seriebus subconcentricis disposita, disco 

 nudo, margine modiee incrassato aut sat tenui, nigro nudoque aut 

 cinerascente et tenuiter subpruinoso. 



Distr. Ad saxum diabasicum loco calcario ad Simonsby in Pargas 

 in Ab. (K. Linkola). 



Thallus variat obscuratus et albidus (sec. Arn.), KHO cum CaCl202 

 non reagens, crystalla calcii oxalat. abundanter continens. Apothecia 

 lat. circ. 1 — O.5 mm, KHO non reagentia. Perithecium rubricoso-fuli- 

 gineum aut (in eodem apothecio) in margine intus subpallidum, hyphis 

 sat leptodermaticis, conglutinatis. Hypothecium rubricoso-fuligineum. 



