3G2 Transactions. — Botany. 



both Pannaria and Coccocarjna agree in that character. As to our lichen 

 being monophyllous, this is a very uncertain and questionable character. 

 Many specimens of it can no more be considered monophyllous than P. 

 ruhiginosa, which latter has never been treated as a Coccocarpia, although its 

 close ally C. plurnbea, Nyl., is by Nylander. I agree with Dr. Lauder Lindsay 

 that Nylander's arrangement, which separates P. ruhiginosa from P. 2^hi77ibea, 

 is a most artificial and unnatural one (vide Trans. Roy. Soc. Edinb,, vol. xxii 

 part I. p. 256). 



15. Lecanora Jtavo-2Mllescens, sj). n. 



Thallus tenuis, subgranulosus, flavo-albicans, interdum evanescens. 

 Apothecia biatorina, disco fulvo piano tandem tumido, marginem pallidum 

 levem demum excludente. Sporce simplices, incolores, longit. 0-015 ad 0-02 

 mm., crassit. O'Ol ad 0*013 mm. 



L. flavo-imllescens, Nyl. in litt. 



Ad ligna. Grandibus sporis satis dignoscitur. 



Thallus thin, subgranular, yellowish-white, sometimes evanescent. Apothecia 

 biatorine, buff or tawny, disk flat, at length tumid, overlapping the pale smooth 

 thalline border. Spores simple, colourless, 0*015 to 0*02 millim. long, 013 

 millim. thick. Closely allied to Z. varia, if not a variety. The specimens 

 with tumid apothecia resemble Z. symmetrica, but differ from it and from all 

 varieties of L. varia in the smooth thalline border of the apothecia, and 

 especially in the much larger size of the spores, which in none of the varieties 

 of L. varia in Leighton, Schoerer, and several German collections that I have 

 examined, exceed 0*011 mm. in length. L. vana is a most polymorphous 

 species. The numerous varieties may be arranged in four sets. 



(1). Those with larger apothecia crowded together, with bold granular 

 flexuose or angular margin, growing on wood, viz : — Parmelia varia, Ehi'h. 

 var. vulgaris, Korb., Leigh t., Exs. 51 ; Lecanora varia var. 2^(tllcscens, Schoer., 

 Exs. 325. 



(2). Those with minute apothecia, with pallid powdery margin and flat 

 disk, sometimes a little convex, viz : — Lecanora varia var. hypopta, Ach. ; 

 L. aitema, Ach. ; L. apocrcea, Ach. j Z. sarcopis, Ach. ; Parmelia varia, Leigh t., 

 Exs. 176. 



(3). Those with tumid apothecia, viz : — Lecanora varia var. symmetrica, 

 and other varieties. 



(4). Lecanora varia var. polytropa, with its varieties, growing on stones. 



16. Lecanora thiomela, Nyl. 

 Thallus crustaccus, citrinus, arcolatus, arcolis Iiypothallum fuscum 

 obtcgentibus, linea fusca limitatus. Apothecia minuta, cupula^formia, marginata, 

 nigra, margino thallino citrino cincta. Sporcfi fuscentcs, ellipsoidea?, uni-septatse, 



