316 LICHENACEL. [PHYscra, 
Hab, On the smooth bark of a young tree in a maritime district.— 
Distr, Extremely local and rare, in 8, England.—B, M.: Near Ryde, 
Isle of Wight. 
18. P. erosa Leight. Lich. Fl. (1871) p. 152.—Thallus subor- 
bicular, moderate, shortly laciniate, greyish or glaucous-white ; 
beneath whitish, sparingly fibrilloso-rhizinose ; lacinie crowdedly 
imbricate, more or less ascending, rounded and eroso-lacerate or-at 
length pulverulent at the apices (Ktyellow, CaCl yellow). Apo- 
thecia moderate, brownish-black, the thalline margin subentire ; 
spores oblong, 0,014-20 mm. long, 0,007-10 mm. thick.—Cromb. 
Journ. Bot. 1872, p. 358; Leight. Lich. Fl. ed. 3, p. 189.—Par- 
melia erosa Borr. Eng. Bot. Suppl. 1837, t. 2807. Borrera ceesia 
y. albinea (non Ach.) Mudd, Man. p. 108, t. ii. f£. 81; Cromb. 
Lich. Brit. p. 39. Squamaria tribacia Sm. Eng. Fl. ii. p. 194 pro 
parte.—Brit. Eas.: Leight. n. 266; Larb. Caesar. n, 24; Lich. Hb. 
n. 294, 
A well-marked species somewhat resembling P. tribacia, from which 
it is well distinguished by the efarinose and esorediate thallus, the apices 
of the lacinie, and the different chemical reactions. The apothecia, 
which with us are extremely rare, are chiefly central, numerous, with the 
thalline margin at length subcrenate. 
Hab. On trees, walls, and rocks in maritime and upland districts.— 
Distr. Not very general nor common throughout England and in the 
Channel Islands ; rare in 8. Scotland, the S.W. Highlands and 8. Gram- 
ians ; not yet seen in Ireland.—B. M.: Rozel, St. Quen’s, and La Moye, 
sland of Jersey; Jerbourg and Moulin Huet, Island of Guernsey. Bex- 
hill and Hurstpierpoint, Sussex; Porchester, Hants; Plymouth and 
Wembury, 8. Devon; near Penzance and Withiel, Cornwall; St. Mary’s, 
Scilly ; near Swindon, Wilts; Malvern, Worcestershire; Nannau, Dol- 
gelly, Barmouth, and Aberdovey, Merionethshire; near Ayton, Cleve- 
fond, Yorkshire ; near Staveley, Westmoreland. New Galloway, Kirk- 
cudbrightshire ; Barcaldine, Argyleshire; Ben Lawers, Perthshire. 
19. P. astroidea Nyl. Act. Soc. Linn. Bord. sér. 3, i. (1856) 
p. 308.—Thallus orbicular, thin, closely adpressed, granulose or 
leprose in the centre, laciniato-effigurate at the circumference, 
greyish-white ; beneath whitish, black fibrilloso-rhizinose; lacinie 
narrow, contiguous (K yellow, CaCl} yellow). Apothecia innato- 
sessile, small, concave or plane, brownish-blackish, naked. or prui- 
nose, the thalline margin inflexed, crenulate; spores ellipsoideo- 
oblong, 0,017-26 mm. long, 0,008-11 mm. thick—Cromb. Lich. 
Brit. p. 39; Leight. Lich. Fl. p. 153, ed. 3, p. 189.—Borrera 
astroidea et 3. Clementi Mudd, Man. p. 108, t. ii. f. 82. Parmelia 
astroidea Clem. Ens. Add. (1807) p. 302. Squamaria Clementi 
Sm. Eng. Fl. vy. p. 196. Puarmelia Clementi Turn. Trans. Linn. Soc. 
ix. p. 146, t. 18. f.1; Gray, Nat. Arr. i. p. 489; Tayl. in Mack. 
Fl. Hib. ii. p. 147. Lichen Clementi Eng. Bot. t. 1779.—Parmelia 
