PHYSCFA.] rHYSCIET. 297 



glaucous-white. Apothecia small or moderate, nearly plane, with 

 entire thalline margin. Mudd, Man. p. 112; Cromb. Lich. Brit, 

 p. 37 ; Leight. Lich. Fl. p. 142, ed. 3, p. ISl.Physria villosa, var. 

 Dicldeana Linds. Trans. Roy. Soc. Edin. t. xxii. (1867) p. 254. 



Apparently but an accidental state of the type, depending upon the 

 nature of the habitat. It is distinguished by the pale thallus and the 

 entire margin of the apothecia, which latter character, however, some- 

 times occurs in the type itself. 



Hab. On shady rocks in maritime districts. Distr. Very local and 

 rare in the Channel Islands (?) and in N.E. Ireland. B. M. : Newcastle, 

 co. Down. 



3. P. parietina De Not. Mem. R. Ac. Sc. Turin, ser. 2, x. (1849) 

 p. 387. Thallus suborbicular, appressed, imbricato-lobed, smooth, 

 yellow ; beneath paler or pale-whitish, sparingly fibrilloso-rhizinose ; 

 lobes somewhat plane or concave, rounded and crenate at the mar- 

 gins (K^violet-purplish, CaCl~). Apothecia moderate, concave or 

 plane, subconcolorous, the margin entire or nearly entire ; spores 

 0,012-16 mm. long, 0,007-9 mm. thick. Mudd, Man. p. 113; 

 Cromb. Lich. Brit, p. 38 ; Leight. Lich. Fl. p. 142, ed. 3, p. 131. 

 Parmelia parietina Gray, Nat. Arr. i. p. 438 ; Hook. Fl. Scot. ii. 

 p. 52 ; Sm. Eng. Fl. v. p. 204 ; Tayl. in Mack. Fl. Hib. ii. p. 141. 

 Lichen parietinus Linn. Sp. PI. (1753) p. 1143 ; Huds. Fl. Angl. 

 p. 447 ; Lightf. Fl. Scot. ii. p. 822 ; Eng. Bot. t. 194 ; With. Arr. 

 ed. 3, iv. p. 34. Lichenoides vulgare simiosum foliis et scutellis luteis 

 Dill. Muse. 180, t. 24. f. 76. Lichenoides crusta foliosa scutellata, 

 flavescens Dill, in Bay Syn. ed. 3, p. 72, n. 59. Brit. Exs. : Leight. 

 n. 10 ; Mudd, n. 85 ; Larb. Lich. Hb. n. 9 ; Bohl. n. 12. 



A very common and well-known plant, easily recognized by its bright- 

 yellow, smooth, appressed thallus. At first sight it looks as if it were a 

 Parmelia, but its essential characters are those of this genus. It varies 

 considerably in colour and in the character of the laciuise, which give 

 rise to the forms and varieties described. With us, as elsewhere, it is 

 commonly fertile, the apothecia being chiefly central and crowded, with 

 the margin somewhat thickish and inflexed or thin and entire. The 

 spermogones are not very frequent in the type. They are usually more 

 or less congregate, inclosed in thalline protuberances, with sperinatia 

 0,0025 mm. long, 0,0015 mm. thick. 



Hab. On the trunks and branches of trees, old pales, and walls, in mari- 

 time, lowland, and upland districts. Distr. Very general and plentiful 

 throughout Great Britain and probably Ireland. B. M. : Bury St. Ed- 

 munds, Suffolk ; Eclgeware, Middlesex ; Lydd, Kent ; Lewes, Sussex ; 

 Appuldurcombe, Isle of Wight ; Plymouth, Devonshire ; Cirencester, 

 Gloucestershire; Windsor, Berkshire ; Madingley Park, Cambridgeshire ; 

 near Worcester ; Harboro' Magna, Warwickshire ; Grimsbury Green, 

 Northamptonshire ; Matlock and Buxton, Derbyshire ; near Shrewsbury, 

 Shropshire; Island of Anglesea ; Cleveland, Yorkshire ; Levcns, West- 

 moreland; Ilexham, Northumberland. New Galloway, Kirkcudbright- 

 shire ; near Stirling ; Finlarig, Killin, Perthshire : Dundee, Forfarshire ; 

 Drum and Castleton of Braemar, Aberdeenshire ; Abernethy, Banffshire ; 



