PARMELTA.] PARMELIET. 241 



entire or crenulate ; spores 0,014-19 mm. long, 0,009-12 mm. 

 thick. Gray, Nat. Arr. i. p. 440 : Hook. Fl. Scot. ii. p. 53 ; Sin. 

 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 Liau. Sp. PI. (1753) p. 1142; 

 Huds. Fl. Augl. p. 531; Lightf. Fl. Scot. ii. p. 816; With. Arr. 

 ed. 3, iv. p. 33 ; Eng. Bot. t. 603. Liclienoides vulgatissimum 

 cinereo-glancum laeiniosum et cirrhosum Dill. Muse. 118, t. 24. 

 f. 83 A. Lishenoides crusta foliosa, superne cinereo-glaiwa, inferne 

 nigra et cirrhosa, scutettis nig ricantibus Dill, in Hay, Syn. ed. 3, 

 p. 72. n. 16. Under the type was included also the following form 

 by most of our earlier authors. Brit. Exs. : 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 subsniooth is usually isidioso-scabrid 

 on the rugae. It is seldom fertile, the apothecia, which are at first 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 nun. long, ab mt 0,001 mm. thick. The parasites Dothidea homosteyia 

 Xyl. and A.brothallus parusiticiis Xvl. (Lichen jxtrasiticus Sin. Eng. Bot. 

 t. 1866) are often met with on the thallus of this species and of the form 

 here desciibed. 



Hal). 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 

 (iiierusey. Near Brighton, Sussex ; Basingstoke, Hampshire ; near Pen- 

 zance, Cornwall : Malvern Hills, Worcestershire ; Wrekin Hill, Shrop- 

 shire; Lambeth, S. Wales; Island of Anglesea ; Stavely, Westmore- 

 land. Appin, Argyleshire ; Killin, Ben Lawers, Abernethy, Black Wood 

 of Ranuoch, and Ben Yrackie, Perthshire ; Cortachy, Forfarshire ; Por- 

 tlethen, Kincardineshire ; Corriemulzie, Braemar, Aberdeenshire ; Ben 

 Nevis, Inverness-shire. 



Form furfuracea Schaer. 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. 138, cd. 3, p. 127; Cromb. Linn. Soc. Journ. Bot. xvii. 

 p. 573. Pannelia horrescens Tayl. in Mack. Fl. Hib. ii. p. 144 

 pro parte. Liclienoides vulgatissimum cinereo-glaucum lacunosum et 

 cirrhosum Dill. Muse. 188, t. 24. f. 83 c, v.Brit. Exs. : Leight. 

 n. 46 pro parte ; Larb. Lich. Hb. n. 211 ; Bohl. n. 11. 



Remarkable on account of the isidiose furfur with which it is frequently 

 covered and which obliterates the lobes except at the circumference, 

 giving it a panniform appearance. Smaller and sterile states in this con- 

 dition, and some very sparingly isidiiferous, are the form panniformis 

 (Crornb. 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 thalliue margin sometimes exasperate with 

 the isidia. 



Hab. On rocks, walls, and trees, chiefly in upland districts. Distr. 



K 



