474 LICHEN ACEl. [LECANORA. 



carea Mudd, Man. p. 161, t. 3. f. 55. Urceolaria calcarea Sm. Eng. 

 Fl. v. p. 172 ; Tayl. in Mack. Fl. Hib. ii. p. 132 ; Gray, Nat. Arr. 

 i.p. 459. Lichen calcareus Linn. Sp. PI. (1753) p. 1140; Huds. 

 Fl. Angl. p. 442; With. Arr. ed. 3, iv. p. 6 pro minima parte. 

 Lichen tessellatus Eng. Bot. t. 553. Urceolaria tessellata Ach., Gray, 

 Nat. Arr. i. p. 460. Brit. Exs.: Leight. n. 13; Mudd, n. 133; 

 Larb. Lich. Hb. n. 166. 



Easily recognized among British species by the whitish or chalky- 

 white thallus. In its more typical condition it is a. concreta (Schaer. 

 Spicil. p. 73) Leight. Lich. Fl". ed. 3, p. 192 (tessellata, Ach.), with the 

 thallus determinate, often subeffigurate at the circumference, and the 

 areolae contiguous, angulose. The apothecia are numerous, often crowded, 

 at times naked, with the proper margin at length discrete from the 

 thalline margin. The spermogones are frequent, dark-brown or blackish, 

 with spermatia aciculari-cylindrical, 0,007-9 mm. long, about 0,001 mm. 

 thick. 



Hab. On calcareous rocks and walls, rarely granitic, in maritime and 

 upland districts. Distr. General and common in limestone tracts of 

 Great Britain and Ireland ; not seen from the Channel Islands. B. M. : 

 Burgh Castle, Suffolk; Peasemarsh, Sussex; Plymouth, S. Devon; near 

 Penzance, Cornwall ; Bathampton Downs, Somerset ; Cunning Dale, 

 near Buxton, Derbyshire ; Malvern Hills, Worcestershire ; Barmouth, 

 Merionethshire ; Great Orme's Head, Carnarvon ; Island of Anglesea ; 

 Bilsdale, Yorkshire; Eglestone and Teesdale, Durham; Levens, West- 

 moreland. Appin and Island of Lismore, Argyleshire ; Craig Tulloch, 

 Blair Athole, Perthshire ; Morrone, Braemar, Aberdeenshire. Dunkerron, 

 co. Kerry ; Maam, Conneinara, co. Galway. 



Yar. $. contorta Nyl. Flora, 1872, p. 554. Thallus effuse, 

 white or greyish-white, the areolse more or less discrete, elevated 

 in the centre, depressed and at times subeffigurate at the circum- 

 ference. Apothecia immersed. Leight. Lich. Fl. ed. 3, p. 193. 

 Aspicilia calcarea /3. contorta Mudd, Man. p. 162. Urceolaria 

 contorta Tayl. in Mack. Fl. Hib. ii. p. 132. Lichen contortus~Ko&m. 

 Deutsch. Fl. ii. (1795) p. 186. Brit. Exs.: Leight. n. 322. 



Distinguished by the form of the discrete or subdiscrete thalline 

 areolas. It usually spreads extensively over the substratum and is well 

 fertile. 



Hob. On calcareous rocks in maritime, but chiefly upland districts. 

 Distr. Somewhat local in Great Britain and Ireland. B. M. : Near 

 Kingskerswell, S. Devon ; Symmond's Yat, Herefordshire ; Ashwood Dale, 

 Derbyshire ; near Oswestry, Shropshire ; Great Orme's Head, Carnarvon- 

 shire"; Teesdale, Durham. The Ochils, near Stirling; Craig Tulloch, 

 Blair Athole, Perthshire ; Craig Guie, Braemar, Aberdeenshire. The 

 O'Donoghue's Prison, Killarney, co. Kerry. 



Form monstrosa Cromb. Grevillea, xix. (1891) p. 57. Thallus 

 effuse, snow-white ; areolse discrete, scattered, rounded, convex, 

 entire at the margins. Apothecia abortive, minute, deeply im- 

 mersed. L. calcarea var. monstrosa Lamy, Bull. Soc. Bot. t. xxx. 

 (1883) p. 392. 



