LECANORA.] LECAtfO-LECIDEEI. 395 



furaceous on the surface. Apothecia minute, scattered ; spores 

 0,010-18 mm. long, 0,006-8 mm. thick. Forma melangica Leight. 

 Lich. Fl. ed. 3, p. 214. Rinodina leprosa * nudangica Norm. Spec. 

 loc. (1868) p. 103. 



A very distinct variety, or probably subspecies, differing in the cha- 

 racters given of the thalfus and apothecia. As observed by Th. M. Fries 

 (Lich. Scand. p. 201), it is very dissimilar in habit to the type, but transi- 

 tion-states are not wanting. 



Hub. On trunks of old trees in an upland tract. Distr. Only sparingly 

 in W. England. B. M. : Haughmond Hill, Shropshire. 



Subsp. L. laevigata Xyl. ex Stiz. St. Gall. Nat. Ges. (1882) 

 p. 358. Thallus effuse, thin, scattered, or scarcely any visible. 

 Apothecia rather small, usually lecideoid ; spores 0,01420 mm. 

 long, 0,007-10 mm. thick. Cromb. Grevillea, xviii. p. 46. L. 

 sophodes /3. Irviqata Ach. Lich. Univ. (1810) p. 357; Cromb. Lich. 

 Brit. p. 49; form lawiyata Leight. Lich. Fl. ed. 3, p. 215. 



Characterized by the little developed thallus, the type of the smaller 

 apothecia, and the thicker spores. The thallus is often evanescent when 

 the apothecia at length appear as if sublecideine (var. lecideina Nyl. olini. 

 in Herb. Mus. Fenn. p. 87). This is the ordinary condition of the plant 

 in this country, where it does not, as elsewhere, occur corticolous. 



Hab. On rocks and walls in maritime and upland situations. Distr. 

 Only sparingly in a few localities in Great Britain and Ireland. B. M. : 

 Cirencester, Gloucestershire. Island of Lismore, Argyleshire ; Craig 

 Guie, Braemar, Aberdeenshire. Carrigaloe, co. Cork ; Lettermore, Con- 

 nemara, co. Galway. 



61. L. exigua Xyl. Flora, 1873, p. 197. Thallus subeffuse, thin, 

 unequal, subgranulate or scattered, whitish, pale-greyish or dark 

 (K , CaCl ); hypothallus indistinct. Apothecia small, plane or 

 convex, crowded, black or blackish ; the thalline margin thin, often 

 somewhat crenulate, whitish ; hypothecium colourless ; spores 

 0,011-18 mm. long, 0,006-8 mm. 'thick. Cromb. Grevillea, xviii. 

 p. 46 ; Sm. Eng Fl. v. p. 187. Rinodina exigua Gray, Nat. Arr. 

 i. p. 450 ; Mudd, Man. p. 143 pro parte. Lecanora sopliodes var. 

 exigua Cromb. Lich. Brit. p. 49 ; form exigua Leight. Lich. Fl. 

 p. 224, ed. 3, p. 214. Lichen exiguus Ach. Prodr. (1798) p. 69 ; 

 Eng. Bot. t. 1849. Lichen pencleus (non Ach.) Eng. Bot. t. 1850. 

 Lecanora periclea Sm. Eng. Fl. v. p. 187 ; Tayl. in Mack. Fl. Hib. 

 ii. p. 133. Rinodina periclea Gray, Nat. Arr. i. p. 449 pro parte. 

 R. exiffua $. periclea Mudd, Man. p. 143. Brit. Exs. : Mudd, n. 

 107; Larb. Lich. Hb. nos. 169, 261. 



Probably descends from L. sophodes, with which at times it seems sub- 

 continent, but differs in the colour of the more effuse thallus, and especi- 

 ally in the smaller spores. It usually spreads extensively, but at times 

 when associated with other crustaceous lichens it is much smaller, though 

 scarcely limited by a distinct hypothallus. It is always well fertile. 



