PLACODEI. 33.'> 



Series V. Placode! Nyl. Mem. Soc. Cherb. vii. (1355) p. 175. 



Thallus variouslj' crustaccous, sometimes evanescent, rarely en- 

 tirely wanting ; medullary layer, when present, usually cretaceous. 

 Apothecia lecanorine, lecideine or biatorine, or lirella3forra ; ])ara- 

 physes discrete or coherent, rarely not distinct. Sperinojjones with 

 various sterigmata and spermatia. — Placodeo' Njl. Mem. Soc. Cherb. 

 ii. (1854) p. 13. 



A very extensive series coniprehendinpr by far the largest number of 

 Lichens. It is very variable in tlie characters of the thallus and fructifi- 

 cation, though the tribes of which it is composed are in both these respect.s 

 related to each other by connectine: links. The less developed thallus, 

 the absence of a distinctly tilameutose medullary layer, and the inferior 

 type of the apothecia distinguish it from the preceding series. The thallus 

 is rarely hypophloeodal, and the apothecia are rarely parasitic. 



Tribe XVIII. LECANO-LECIDEEI Xyl. Flora, 1882, p. 458. 



Thallus crustaccous ; laciniate, squaraose, granulosa or pulveru- 

 lent, sometimes but little visible, occa-sionally absent ; internally 

 rarely entirely cellular, containing gonidia, rarely gonimia ; hypo- 

 thallus more or less distinct. Apothecia lecanorine, lecideine or 

 biatorine, occasionally diftbrm. Spermogones with jointed or simple 

 sterigmata. 



This comprises the numerous species of the Lecanorei aud Lccirleei, 

 formerly in the Nylanderian arrangement regarded as di^^tinct tribes. 

 They are now, however, more naturally united into a single tribe fi'om 

 the circumstance that in some instances lecanorine apothecia are not to 

 be distinguished from lecideine ; while in certain cases normally biatorine 

 apothecia occur in species otherwise entirely referable to the Lecanorei. 

 The tribe is primarily divided into six subtribes (one of which, Heppiei, 

 does not occur in Great Britain), differing from each other in the fructifi- 

 cation. 



Subtribe I. PANNARIEI Xyl. Flora, 1882, p. 458. 



Thallus squamulose or granulose, rarely monophyllous, cellular in 

 texture, containing gonimia, which are usually somewhat monili- 

 form. Apothecia either lecanorine or biatorine, rarely lecideine ; 

 spores 8nse, colourless, simple or variously septate ; paraphvses 

 discrete, often thiekish, generally articulate. Spermogones with 

 jointed sterigmata. 



A subtribe well characterized by the structure of the thallus. Since it 

 contains gonimia it holds much the same position in this as the Teltiyerei 

 in the preceding series, though the texture is otherwise very different. 



56. PANNARIA Del. in Dub. Bot. Gall. (1830) p. 606 ; ^'yl. 

 emend. Flora, 1879, p. 360. — Thallus laciniately divided or squa- 

 mulose. Apothecia lecanorine ; spores ellipsoid or oblong, simple ; 

 hymenial gelatine variously tinged with iodine. Spermogones with 

 spei-matia somewhat short, cylindrical, slightly thickened and obtuse 

 at either apex. 



