LECANORA, | LECANO-LECIDEET. 391 
polari-bilocular, 0,011-15 mm. long, 0,006-8 mm. thick.—Cromb. 
Grevillea, xviii. p. 46.—Placodium chalybewm Mudd, Man. p. 134 ; 
Cromb. Lich. Brit. p. 46; Leight. Lich. Fl. p. 179, ed. 3, p. 165. 
Purmelia chalybcea Duf. in Fr. Lich. Eur. (1831) p. 125.—Brit. Exs.:. 
Cromb. n. 59, 
Easily recognized by the colour of the thallus, which is somewhat 
thickish, small or considerably expanded, occasionally somewhat lobed or 
lobato-crenate at the circumference. The apothecia are numerous and 
crowded, becoming, when moistened, turgid, somewhat prominent, and 
livid-brown, 
Hab. On calcareous rocks in maritime and mountainous districts.— 
Distr. Local in S.W. and N. England, N. Wales, and the Central Gram- 
ans, Scotland.—B. M.: Babbicombe, Devonshire; Llanymynech Hill, 
hropshire ; Great Orme’s Head, Carnarvonshire; Penhill, Yorkshire ; 
Craig Tulloch, Blair Athole, Perthshire. 
55. L. variabilis Ach. Lich. Univ. (1810) p. 369.—Thallus 
determinate, adnate, thinnish, diffracto-areolate, greyish-brown or 
lurid-grey (K+ violet), usually limited by a thin blackish hypo- 
thallus. Apothecia submoderate, slightly prominent, plane or con- 
- vex, black, subpruinose (K—); the thalline margin entire, usually 
white-suffused ; spores broadly ellipsoid, polari-bilocular, 0,013-16 
mm. long, 0,007—0,010 mm. thick.—Cromb. Grevillea, xviii. p. 46. 
Placodium variabile Leight. Lich. Fl. p. 179, ed. 3, p. 165. Lichen 
variabilis Pers. in Ust. Ann. (1794) p. 26. 
Similar to the preceding species, but distinguished by the thinner, 
darker non-effigurate thallus, the more prominent apothecia, and the 
rather larger spores. In the British specimens the hypothallus is only 
sparingly visible. The apothecia, which when moistened are livid-brown, 
are usually numerous, at times crowded and somewhat angulose. 
Hab. On calcareous rocks in upland hilly situations.— Distr. Seen only 
from W. and Central England, and (fide Leight.) N.W. Ireland (Conne- 
mara, Galway).—B. M.: Bathampton Downs, Somersetshire; Grove 
Lane, Cirencester, Gloucestershire; Cunning Dale, Buxton, Derbyshire ; 
Llanymynech Hill, Shropshire. 
Var. 3. ecrustacea Nyl. ea Cromb. Grevillea, xviii. (1889) p. 46. 
—Thallus indistinct. Apothecia small, lecideoid, subinnate, at 
length immarginate ; otherwise as in the type.—Placodium variabile 
var. ecrustacea Nyl. Lich. Scand. (1861) p. 1389. P. Agardhianum 
Hepp (non Ach.), Leight. Lich. Fl. ed. 3, p. 165, 
Differs in the absence of a thallus and in the character of the apothecia. 
But for the form of the spores it might be taken for a Lecidea, 
Hab. On calcareous rocks in maritime and upland districts. —Dvstr. In 
S.W., N.W. England, and S. Wales.—B. M.: Anstey’s Cove, Torquay, 
S. Devon; Bathampton Downs, Somerset; Tenby, Pembrokeshire ; 
Lamplugh, Cumberland. 
