240 LICHENACEI, [PARMELIA. 
9. P. scortea Ach. Lich. Univ. (1810) p. 461.—-Thallus orbicular, 
subcoriaceous, smooth, somewhat shining, very thinly isidiose in the 
centre, sinuato-lobed, greyish-white or whitish; beneath rugose, 
brownish, densely black-fibrillose ; lobes short, rounded, undulate, 
inciso-crenate at the margins (K+Y allowely CaCly veaaish ~ APO- 
thecia moderate, scattered, reddish-brown, the margin subentire; 
spores 0,007-11 mm. long, 0,005-7 mm. thick.—Sm. Eng. FI. v. 
p- 203.—Parmelia tiliacea var. scortea Mudd, Man. p. 93; Cromb. 
Lich. Brit. p. 33; Leight. Lich. Fl. p. 131, ed. 3, p. 122. Lichen 
scorteus Ach. Prodr. (1798) p.119; Eng. Bot. t. 2065.— Brit. Evs.: 
Leight. n. 87; Larb. Cesar. n. 18. 
. 
Closely allied to P. tiliacea; but its thicker and less appressed thallus, 
its normally whiter colour, the central isidia, the form of the lobes, and 
the more scattered apothecia warrant us in regarding it, with the older 
authors, as a distinct species, in which light also it is now viewed by 
Nylander (Pyr. Or. p 5)... The isidia, which are greyish, becoming 
blackish in age, though chiefly central, are sometimes sprinkled over the 
thallus nearly to its circumference. In this country, as elsewhere, the 
apothecia are very rare, and even when present are but few. The sper- 
mogones, which are more common, are similar to those of P. tiliacea. 
Aab. On trees and old pales, rarely on rocks, in maritime and upland 
districts —Distr. Local and scarce in England (chiefly in the South), the 
Channel Islands, and Wales; very rare in 8.W. Scotland and in 8. Ire- 
land.—B. M.: L’Etacq, Island of Jersey; Island of Sark. Near Bury 
St. Edmunds, Suffolk; near Lewes and Henfield, Sussex; Shanklin, 
Isle of Wight; New Forest, Hants; Bolt Head, Devonshire; Stone- 
henge, Wilts; Harboro’ Magna and Newbold-on-Avon, Warwickshire ; 
Twycross, Leicestershire; Little Stretton, Shropshire; Holyland, Pem- 
brokeshire; Dolgelly and near Barmouth, Merionethshire; Island of 
Anglesea; Stokesley, Cleveland, Yorkshire; near Eglestone, Durham ; 
near Stavely, Kendal, Westmoreland. Near Dumfries; Castle Douglas, 
Kirkcudbrightshire. Askew Wood and Dunkerron, co. Kerry. 
Form concrescens Cromb.—-Thallus orbicular, small, isidiose ; 
lobes very short, narrowly dissected and crowded. Apothecia un- 
known. 
A panniform condition, referred to in Leight. Lich. Fl. ed. 1, p. 188, as 
approaching var. concentrica of P.revoluta, It is, however, neither spherical 
(but only somewhat convex) nor free; while the isidia and other cha- 
racters show that it belongs to P. scortea. The specimens seen are 
sterile. 
Hab. In crevices of stone walls in a maritime district—Distr. Ex- 
tremely local and rare in 8, W. England.—B. M.: Bolt Head, 8. Devon. 
10. P. saxatilis Ach. Meth. (1803) p. 204.—Thallus orbiculari- 
expanded, membranaceous, subimbricate, reticulato-rugulose, often 
somewhat isidioso-scabrid, greyish-white or glaucous-grey, beneath 
black, rhizineo-fibrillose ; laciniee sinuato-incised or sinuato-lobed, 
. +-yellowish, - : 
retuse at the apices; (K Tallon: tee ‘ented, CaCl—). Apothecia 
moderate cr somewhat large, badious or brownish, the margin thin, 
