gyalecta] lecideace^ 5 



Apothecia closed at first, the margia (exciple) radiately 

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



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

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

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

 fiesh-coloured, the margin white, oonnivent, 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 ; hymenial 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. Thelotrema 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); Oromb. 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 (M^m. 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 rooks 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.— B. M. Shiere, 

 Surrey; Mount Harry, Pulking, and the Downs, Sussex; Torquay 

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

 shire ; Cunning Dale and Deep Dale, Buxton, Derbyshire ; Eglwyseg 

 Eocks, near Llangollen, Denbighshire; Ingleborough, Yorkshire; 

 Eglestone and near Barnard Castle, Durham ; Leveus, 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 

 /g;_ CaCl — ). Apothecia moderate, superficial and prominent ; 

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

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

 hypothecium colourless ; paraphyses slender, not well discrete ; 

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

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



