GYALECTAJ LECIDEACE^ 5 



xVpothecia closed at first, the margia (exciple) rad lately 

 fissured (Petractis Fr. Summa p. 120 (1846)). 



1. Gr. exanthematica Fr. Lioh. Eur. p. 197 (1831). — Thallus 

 effuse, very thin, continuous, greyish-white (K — , CaCl — ), often 

 obsolete. Apothecia small, immersed, pale-yellow or yellowish- 

 flesh-coloured, the margin white, connivent, radiately (3-6) fissured, 

 at length exposing the epithecium ; hypothecium pale ; para- 

 physes slender; spores 8nate, fusiform, 3-septate, 0,015-20 mm. 

 long, 0,006-7 mm. thick ; hy menial gelatine pale bluish with 

 iodine. — Lichen exanthematicus Sm. in Trans. Linn. Soc. i. p. 81 

 t. 4. f. 1 (1791); Dicks. Crypt, fasc. iii. p. 14; With. Arr. ed. 3, 

 iv. p. 22; Engl. Bot. t. 1184. Tlielotrema exanthematica S. F. 

 Gray Nat. Arr. i. p. 444 (1821); Hook. Fl. Scot. ii. p. 45 and 

 in Sm. Engl. Fl. v. p. 161 ; Leight. Angio. Lich. p. 32, t. 12. 

 f. 3 ; Tayl. in Mackay Fl. Hib. ii. p. 103. Lecidea exanthematica 

 Nyl. in Mem. Soc. Cherb. v. p. 119 (1857); Cromb. Lich. Brit. p. 62; 

 Leight. Lich. Fl. p. 334 ; ed. 3, p. 355. Petractis exanthematica 

 Fr. Summa p. 120; Mudd Man. p. 278, t. 5. f. 117. 



Exsicc. Leight. n. 256. 



A very typical lichen, which has been referred by authors to several 

 distinct genera and even tribes. It has frequently been regarded as 

 Thelotrema, but, as Nylander observes (Mem. Soc. Cherb. t. iii. 

 p. 181 nota), the hypothecium presents in the texture of its lateral 

 portions no jointed filaments. The peculiar apothecia are char- 

 acteristic of Gyalecta ; they are at first closed, appearing as if verru- 

 carioid, but at length become disciform, often disappearing in age, 

 leaving numerous whitish depressions or pits on the substratum. 



Hah. On calcareous rocks and cretaceous stones in upland, rarely 

 maritime, tracts. — Distr. Not uncommon in England, rare in the S.W. 

 Highlands of Scotland and in the N. and S. of Ireland.— 5. M. Shiere, 

 Surrey ; Mount Harry, Fulking, and the Downs, Sussex ; Torquay- 

 and near Babbicombe, Devon ; Park Corner, Cirencester, Gloucester- 

 shire ; Cunning Dale and Deep Dale, Buxton, Derbyshire ; Eglwj-seg 

 Eocks, near Llangollen, Denbighshire ; Ingleborough, Yorkshire ; 

 Eglestone and near Barnard Castle, Durham ; Levens, Westmoreland ; 

 Lamplugh, Cumberland ; Achosragan Hill, Appin, Argyll ; near 

 Belfast, Antrim ; Kylemore Castle, Connemara, Galway ; Killarney, 

 Kerry. 



Apothecia subbiatorine, concave, the margin typically entire. 

 Spores 3- or pluri-septate and often variously divided. 



2. G. cupularis Schser. Enum. p. 94 (1850). — Thallus effuse, 

 very thin, continuous, subleprose, whitish or pale -greyish 

 (K — , CaCl — ). Apothecia moderate, superficial and prominent ; 

 epithecium impressed, concave, flesh-coloured or yellowish-rod, 

 the margin thickish, entire or at times radiato striate, whitish ; 

 hypothecium colourless ; paraphy.ses slender, not well discrete ; 

 spores 8nate, ellipsoid, 3- then multi-septate and muriform, 

 0,015-17 mm. long, 0,007-9 mm. thick; hymenial gelatine 



