PARMELIA | PARMELIACEE 135 
Exsice. Larb. Cesar. n. 20; Leight. n. 231. 
Somewhat similar to P. swlcata, but differing in the form of the 
soredia and in the thalline reactions. Apothecia are rare in British 
specimens, they are chiefly central and become perforate with age. 
Spermatia are lageniform (broadly clavate), 4°5 » long, 1 p thick. 
Hab. On trunks of old trees, rarely on rocks in wooded districts. 
—Distr. General in the Channel Islands and in 8. and W. England, 
rarer in Scotland and Ireland.—B. M. Rozel, Jersey ; near Jerbourg, 
Guernsey ; near Penzance and Withiel, Cornwall; Basingstoke and 
Lyndhurst, Hants; Ryde and Shanklin, I. of Wight; near Brighton, 
Henfield, Hayward’s Heath, Angmering Park, Hurstpierpoint, 
Hastings and near St. Leonards, Sussex ; Maidstone, Kent ; Waltham- 
stow, near Maldon and Great Totham, Essex ; Kemble and Sapperton, 
Gloucestershire; near Oxford; Harboro’ Magna, Warwickshire ; 
Hindlip and Malvern, Worcestershire ; 'wycross, Leicestershire ; 
Barmouth and Dolgelly, Merioneth ; Dynevor Castle, Caermarthen- 
shire ; near Kendal, Westmoreland; New Galloway, Kirkcudbright- 
shire ; West Kilbride, Ayrshire; Riverstown, Cork; near Limerick ; 
Dunkerron, Kerry ; Westport and Achill Island, Mayo. 
21. P. ambigua Ach. Meth. Lich. p. 207 (1803).—Thallus 
orbicular, closely adnate, straw-coloured or glaucous-grey, sprinked 
with sulphur-coloured soralia, the lobes narrow, somewhat 
pinnatifid, plane, widening outwards ; beneath brownish-black, 
lighter towards the circumference with a few scattered stoutish 
rhizine almost to the edge (K—, CaCl—). Apothecia small, 
with a rather prominent entire or crenulate margin; spores 
oblong or ovoid-oblong, often slightly curved, 7-11 y long, 
2°5-3°5 pw thick.—Borr. in Engl. Bot. Suppl. t. 2796 (two lower 
figs.). Hook. Fl. Scot. ii. p. 55 & in Sm. Engl. FI. v. p. 203 ; 
Leight. Lich. Fl. p. 127 ; ed. 3, p. 118. P. diffusa Mudd Man. 
p. 103 (1861) (non Web.). Lichen ambiguus Wulf. in Jacq. 
Coll. Bot. iv. p. 239 (1790). Parmeliopsis ambiqua Nyl. in Not. 
Sallsk. Faun. & Fl. Fenn. Forh. n. ser. v. p. 121 (1866) ; Cromb. 
Lich. Brit. p. 37 & Monogr. i. p. 263. 
Hasice. Cromb. n. 146; Johns. n. 222; Leight. n. 373; 
Mudd n. 75. 
Well distinguished from P. Mougeotii, which it resembles in the 
yellow soralia by the more developed thallus, by the unbroken lobes, 
the absence of reaction, and the form of the ascospores and spermatia. 
The latter are long, slender and arcuate, about 18°25 yp long, °5 » 
thick. Because they differ from those of other Parmelie, this species 
and P. alewrites, in which they also occur, have been placed by several 
writers in a separate genus, Parmeliopsis. 
Hab. On the trunks of old fir trees near the roots and on old fir 
palings in upland districts.—Dist7. Rare but common where it occurs 
throughout England and Central Highlands, Scotland.—b. M. 
Ightham, Kent; Twycross and Gopsall Park, Leicestershire; near 
Oswestry, Shropshire ; Cwm Bychan, Merioneth; Ingleby Greenhow, 
Yorkshire; Killin, Perthshire; Kinnordy, Forfarshire: Mar Forest 
and Glen Derry, Braemar, Aberdeenshire; Larig Guie, Banffshire ; 
Rothiemurchus, Invernessshire. 
