LECANORA.] LECANO-LECIDEEI. 371 



Subgen. 7. EULECANORA Xyl. Not. Sallsk. pro F. et Fl. 

 Fenn. Forh. n. s. v. (1866) p. 127. Thallus crustaceous, granulose 

 or leprose, very rarely radiate. Apothecia lecanorine or iecideoid ; 

 spores occasionally numerous, simple or variously septate, rarely 

 brown ; hymenial gelatine variously tinged with iodine. Spermo- 

 gones with jointed or simple sterigmata and various spermatia. 



The largest subgenus of Lecanora and in several respects confluent 

 with the preceding subgenera. According to the structure of the apo- 

 thecia and spennogones it is divided into different sections, most of which 

 have been viewed as distinct genera by sporologists. 



A. Spores 8nae (rarely 8-16use), polari-bilocular, 

 rarely simple or 1 -septate, colourless ; 

 hymenial gelatine, especially the thecae, 

 bluish with iodine. Spermogones with 

 jointed sterigmata and straight spermatia. 

 (Eucaloplaca Fr. fil. Lich. Scand. p. 172.) 



a. Apothecia brightly coloured. (CaVopis- 

 meUa Wedd. Mem. Soc. Cherb. t. xix. p. 276.) 



27. L. citrina Ach. Lich. Univ. (1810) 

 p. 402 ; Xyl. Bull. Soc. Bot. Fr. t. xiii. p. 366. Fig. 63. 



Thallus effuse, granuloso-leprose, rimoso-sub- Lecanora cerina Ach. 

 areolate, citrine (K + purplish). Apothecia A spore, x 

 moderate, plane or somewhat convex, orange- 3 ^ : ; Jointe ^ 



11 /-IT- i \ j.1- j-u IT -L- stengmata and 



yellow (K + purple) ; the thalhne margin thin, 8pe rmatia ( x 500. 

 entire, at length obliterated ; spores ellipsoid, 

 polari-bilocular, colourless, 0,010-15 mm. long, 0,005-8 mm. thick. 

 Sm. Eng. Bot. ii. p. 192 ; Tayl. in Mack. Fl. Hib. ii. p. 138 ; 

 Cromb. Grevillea, xii. p. 61. Placodium citrinum Leight. Lich. 

 Fl. p. 177, ed. 3, p. 163. P. murorum subsp. citrinum Cromb. 

 Lich. Brit. p. 45 ; var. e. citrinum Mudd, Man. p. 132. Lichen 

 citrinus Eng. Bot. t. 1793 (three lower figs.). Verrucaria citrina 

 Hoffm. Deutsch. Fl. ii. (1795) p. 193 pro parte. Lichen candelarius 

 Huds. Fl. Angl. p. 444 pro parte ; With. Arr. ed. 3, iv. p. 27 pro 

 parte. Lichenoides crustosum, orbiculis et scutellis flavis Dill. Muse. 

 136, t. 18. f. 18 *.Brit. Exs. : Leight. n. 86 ; Larb. Lich. Hb. 

 n. 8ij. 



Differs at once from L. (Placodiuni) murorum, of which it has fre- 

 quently been regarded as a variety, in not being radiate at the circum- 

 ference, while connecting states are never found. The thallus occasionally 

 spreads extensively, varying somewhat in thickness, at times subevane- 

 scent, and is often of a greenish-yellow colour when growing in shady 

 places, and in old plants is partially more or less greyish-citrine. The 

 apothecia when present (for the plant is often sterile) are generally 

 numerous, at first somewhat innate, becoming at length convex, with the 

 thalline margin excluded. 



Hab. On the mortar of walls, rarely on rocks, very rarely on old 

 trunks of trees, chieflv about towns and villages, in maritime, lowland, 



