PARMELTA. | PARMELIEL. 241 
entire or crenulate; spores 0,014-19 mm. long, 0,009-12 mm. 
thick.—Gray, Nat. Arr. i. p. 440: Hook. FI. Scot. ii. p. 53; Sm. 
Eng. Fl. v. p. 199; Tayl. in Mack. Fl. Hib. ii. p. 144; Mudd, 
Man. p. 94; Cromb. Lich. Brit. p. 34; Leight. Lich. Fl. p. 137, 
ed. 3, p. 126.—Lichen saxatilis Linn. Sp. Pl. (1753) p. 1142; 
Huds. Fl. Angl. p. 531; Lightf. Fl. Scot. ii. p. 816; With. Arr. 
ed. 3, iv. p. 33; Eng. Bot. t. 603. Lichenoides vulgatissinum 
cinereo-glaucum laciniosum et cirrhosum Dill. Muse. 118, t. 24. 
f. 83.4. Lichenoides crusta foliosa, superne cinereo-glauca, inferne 
nigra e& cirrhosa, scutellis nigricantibus Dill. in Ray, Syn. ed. 3, 
p. 72, n. 16.—Under the type was included also the following form 
by most of our earlier authors.—Brit. Hvs.: Leight. n. 203 pro 
parte; Cromb. n. 27. : 
This well-known species is readily recognized by the reticulato-rugu- 
lose thallus. Often very widely spreading, it is one of the largest plants 
of the genus, and though sometimes subsmooth is usually isidioso-scabrid 
on the ruge. It is seldom fertile, the apothecia, which are at tirst urceo- 
late and moderate, becoming at length large and flexuose. The spermo- 
gones, which are not uncommon, are very minute, black, with spermatia 
0,007 mun. long, about 0,001 mm. thick. The parasites Dothidea homosteyia 
Nyl. and Abrothallus parasiticus Nyl. (Lichen parasiticus Sm. Eng. Bot. 
t. 1866) are often met with on the thallus of this species and of the form 
here described. 
Hab. On trees, walls, rocks, and boulders in upland and subalpine, 
sometimes in lowland districts. —Distr. Local throughout Great Britain; 
rare in the Channel Islands; not seen from Ireland.—B M.: Island of 
Guernsey. Near Brighton, Sussex; Basingstoke, Hampshire; near Pen- 
zance, Cornwall; Malvern Hills, Worcestershire; Wrekin Till, Shrop- 
shire; Lambeth, 8. Wales; Island of Anglesea; Stavely, Westmore- 
land. Appin, Argyleshire ; Killin, Ben Lawers, Abernethy, Black Wood 
of Rannoch, and Ben Vrackie, Perthshire ; Cortachy, Forfarshire; Por- 
tlethen, Kincardineshire; Corriemulzie, Braemar, Aberdeenshire ; Ben 
Nevis, Inverness-shire. 
Form furfuracea Scher. Spic. (1840) p. 455.—Thallus much 
expanded, greyish-white, densely covered with greyish-brown 
isidia : otherwise as in the type.— Mudd, Man. p. 95; Leight. Lich. 
Fl. p. 188, ed. 3, p. 127; Cromb. Linn. Soc. Journ. Bot. xvii. 
p- 573.—Parmelia horrescens Tayl. in Mack. Fl. Hib. ii. p. 144 
pro parte.—Lichenordes vulgatissimum cinereo-glaucum lacunosum et 
cirrhosum Dill. Muse. 188, t. 24. f. 83c, p.—Brit. Hxs.: Leight. 
n. 46 pro parte; Larb. Lich. Hb. n. 211; Bohl. n. 11. 
Remarkable on account of the isidiose furfur with which itis frequently 
covered and which obliterates the lobes except at the civcumference, 
giving it a panniform appearance. — Smaller and sterile states in this con- 
dition, and some very sparingly isidiiferous, are the form panniformis 
(Cromb. Grevillea, xv. p. 75). The thallus is often dark-grey, and occa- 
sionally becomes centrifugal from the decay of the central portions, when 
it may present merely a narrow circumferential border. The apothecia, 
which are frequent, have the thalline margin sometimes exasperate with 
the isidia. 
Hab. On rocks, walls, and trees, chiefly in upland districts.— Distr. 
R 
