Buellia. 165 



Thalhis crustaceus, uniformis aut ambitu lobatus, aut squa- 

 mulosus aut laciniatus, rhizinis veris nullis et hypothallo aut hy- 

 phis medullaribus substrato affixus, strato corticali nullo distincto 

 aut in speciebus magis evolutis [subg. Catolechia (Flot.) Th. Fr.] 

 pseudoparenchymatico, e cellulis leptodermaticis formato, superne 

 thallum obtegente. Stratum medullare stuppeum, hyphis implexis,. 

 tenuibus, membrana tend, lumine cellularum comparate sat lato 

 Gonidia protococcoidea. Apothecia lecideina, thallo innata, mox 

 emergentia adpressaque, aut immersa permanentia, aut raro de- 

 mum substipitata, nigra aut fuscescentia aut varie pruinosa. Ex- 

 cipulum proprium, gonidiis destitutum, ex hyphis conglutinatis 

 formatum, membranis haud incrassatis. Sporae ellipsoideae aut 

 oblongae, fuscescentes riigricantesve, 1 — 3-septatae aut raro sub- 

 murales x ), 8:nae aut raro plures paucioresve, interne membrana 

 plus minusve incrassata. Conceptacula pycnoconidiorum thallo 

 immersa aut leviter prominula. „Sterigmata pauciarticulata aut 

 exarticulata. Pycnoconidia oblongo-cylindrica aut oblonga aut 

 cylindrical (Linds., Mem. Sperm, p. 251, Th. Fr., Lich. Scand. p. 

 586, Hue, Addend, p. 222). 



1. Thallus colore variabilis, glaucescens aut cinerascens aut 

 albidus aut flavescens lutescensve aut obscuratus. Medulla jodo 

 non reagens. Apothecia vulgo mediocria aut sat parva, adpressa. 



1. B. disciformis (Fr.) Br. et Rostr., Lich. Dan. (1869) p. 

 111. Lecidea Fr. in Moug. St. Vog. (1823) n. 745 (Th. Fr., 1. c); 

 Wainio, Adj. Lich. Lapp. II (1883) p. 111. Buellia parasema Th. 

 Fr., Lich. Scand. (1874) p. 589. 



Thallus crustaceus, uniformis, albidus aut cinerascens aut 

 glaucescens aut raro stramineoflavescens vel subrubescens, KHO 

 flavescens (aut parcissime crystallos rubros formans). Apothecia 

 mediocria aut sat parva, circ. 2 — 0,5 millim. lata, adpressa, disco 

 piano aut clemum convexo, nudo nigroque aut pruinoso, margine 

 tenui aut mediocri, persistente aut subpersistente. Hypothecium 

 fusco-nigricans fuscescensve. Sporae 8:nae, 1 — 3-septatae, vulgo 

 long. circ. 0,oi6— 0,0 3 4 (— 0,0 9), crass. 0,0 5 — 0,oi2 millim. 



*) L. perusta Nyl. in Cromb. Lich. Kerg. p. 188, sporis simplicibus de- 

 mum nigricantibus instructa, forsan ad hoc genus non pertinet. 



