PARHELIA.] PARMELIEI. 233 



It may be divided into the following sections (or subgenera) and sub- 

 sections, according to the presence or absence of rhizinse and the colour of 

 the thallus. 



A. IIHIZINOS^E. Thallus more or less distinctly fibrilloso- 

 rhizinose beneath (subgenus Hyporhizia Cromb. Grevillea, xv. 

 (1887) p. 74). 



a. Glaucescentes. Thallus normally grey, greyish-white or 

 glaucous. 



1. P. perlata Ach. Meth. (1803) p. 216. Thallus orbicular or 

 expanded, imbricato-lobed, smooth, glaucous- or greyish-white ; 

 beneath somewhat shining, brownish-black or blackish, paler at the 

 circumference, with short scattered rhizina3 ; lobes rounded, often 

 white-sorediate towards the margins (K+^f- yellow ' Cad"). 

 Apothenia moderate or large, scattered, badio-reddish, the margin 

 thin, entire ; spores 0,011-17 mm. long, 0,007-12 mm. thick. 

 Gray. Nat. Arr. i. p. 437 ; Hook. Fl. Scot. ii. p. 52 ; Sm. Eng. Fl. 

 v. p. 200 ; Tayl. in Mack. Fl. Hib. ii. p. 148 ; Mudd, Man. p. 92 ; 

 Cromb. Lich. Brit. p. 33 ; Leight. Lich. Fl. p. 128, ed. 3, p. 119. 

 LicJien perlatus Linn. Syst. Nat. ed. 12 (1767) p. 712; Huds. 

 Fl. Angl. p. 448 ; Lightf. Fl. Scot. ii. p. 839 ; With. Arr. ed. 3, 

 iv. p. 68. Lichenoidts ylawcum perlatum, subtas nigrum et cirrhosum 

 Dill. Muse. 147, t. 20. f. 39, A, B, D, E. Brit. Exs. : Leight. n. 76, 

 392 ; Larb. Lich. Hb. n. 291. 



Several species were included under this which have been definitely 

 separated by the chemical reactions of the medulla. P. perlata is now 

 seen to be a much less variable plant than was supposed, though the 

 thallus varies in the presence or absence of soredia. The apothecia are 

 very rare in this country, nor are the spermogones often seen. When 

 present, they are scattered, minute, blackish, with spermatia about 

 0,00-j-G mm. long, scarcely 0,001 mm. thick. 



Hob. On the trunks of old trees and on rocks in maritime and upland 

 tracts. Distr. General and often plentiful in most parts of Great Britain 

 and in the Channel Islands; apparently rare in Ireland. B. M. : Islands 

 of Jersey, Sark, and Guernsey. St. Leonard's Forest, near Brighton, 

 Ilenfield, and Arundel, Sussex ; Lyndhurst, New Forest, Hants ; Isle of 

 Wight ; Torquay, South Brent, Hay Tor, Dartmoor, and Ilfracombe, 

 Devonshire ; Bocconoc, near Penzance, and Withiel, Cornwall ; near 

 Cheltenham, Gloucestershire ; Twycross, Leicestershire ; Harboro' Magua, 

 Warwickshire ; Wrighton Park, Herefordshire ; Haughmond Hill, Shrop- 

 shire ; Llanbedr, Barmouth, and Dolgelly, Merionethshire ; Bousdale 

 Gill, Cleveland, Yorkshire ; Stavely, Kendal, and Windermere, West- 

 moreland. New Galloway, Kirkcudbrightshire ; near Inverary and Bar- 

 caldine, Argyleshire ; Loch Katrine and Killin, Perthshire ; S. of Fort 

 William, Lochaber, Inverness-shire ; Applecross, lloss-shire. Near 

 Cork : Dunkerron, co. Kerry. 



Subsp. P. ciliatl Nyl. Flora, 1878, p. 247. Thallus moderate 

 or large, imbricato-lobed, smoothish, often isidiiferous, white or 



