222 CYCLOCARPINE [ PLACODIUM 
grows up around the apothecia, so that they almost appear to have 
a thalline margin. 
Hab. On trunks of trees in maritime and inland districts.— 
Distr. General in wooded districts of most parts of the British 
Isles.—B. M. Guernsey ; Boconnoc, Cornwall; near Plymouth, Devon; 
New Forest, Hants; Shanklin and near Ryde, I. of Wight; Hurst, 
St. Leonard’s Forest, Lewes, Brighton, Shoreham, Newhaven, Hay- 
wards Heath, Wakehurst and Denny, Sussex; Epping Forest, 
Widdington, Langford, Stansted and Mountfitchet, Essex ; Cirencester, 
Gloucestershire ; Oswestry, Shropshire; Barmouth, Merioneth ; Tre- 
friw, Carnarvonshire; Anglesea; Cleveland, Yorkshire; Teesdale, 
Durham ; Levens and Windermere, Westmoreland; Largs, Ayrshire ; 
near Stirling; Finlarig, Kenmore and Aberfeldy, Perthshire ; Cork ; 
Kenmare and Glenmore Lake, Kerry ; Kylemore, Connemara. 
Var. festivum A. L. Sm.—Thallus thin, continuous or areolate, 
light- or dark-grey, often evanescent. Apothecia small, often 
convex, the proper margin becoming flexuose and crenulate or 
disappearing.—Lichen crenularius With. Arr. ed. 3, iv. p. 405 
(errore L. crenulatus, p. 22) pro parte.  Lecidea czesio-rufa var. 
festiva Ach, Syn. Lich. p. 44 (1814). Lecanora ferruginea var. 
festiva Nyl. Lich, Scand. p. 143 (1861) ; var. erenularia & f. festiva 
Cromb. Lich. Brit. p. 47 (1870); ff. saaieola, festiva Leight. 
Lich. Fl. pp. 219, 220 (1871); ed. 3, pp. 208, 209. Callopisma 
ferrugineum var. festivum Mudd Man. p. 139 (1861). 
Easicc. Johns. nos. 104, 312; Larb. Lich. Hb. n. 165; Leight. 
n. 85; Mudd n. 102. 
Differs chiefly in habitat from the species. The thallus gives very 
little reaction with potash, and when dark-grey gives none at all. 
The apothecia may be scattered or very crowded. Withering’s name 
L. crenularius refers to a plant on trees as well as rocks. 
Hab. On rocks, chiefly siliceous, in maritime and upland districts. 
—Distr. Somewhat general throughout the —British Isles.—B. M. 
Jersey; Alderney; Sark; St. Austell, St. Minver and near Penzance, 
Cornwall; Kingsbridge and Torquay, Devon; Beeding, Sussex ; 
Haughmond Hill, Shropshire ; Llandyssil, Cardiganshire ; Aberdoyvey, 
Merioneth ; Holyhead Mt., Anglesea, Bettws-y-Coed, Carnarvonshire ; 
Malvern, Worcestershire; near Roseberry, Cleveland, Yorkshire ; 
Egglestone and Teesdale, Durham; Chollerford, Northumberland ; 
Whitehaven and St. Bees, Cumberland; Barcaldine, Argyll; The 
Trossachs, Perthshire ; Lundie Craigs and West Water, Forfarshire ; 
Portlethen, Kincardineshire; near Ballater, Aberdeenshire; near 
Innisearra, Cork; Saltees, Wexford; Kilkee, Clare; Kylemore, 
Galway; Clare Island and Achill, Mayo; Glenarm, Antrim. 
Form ferruginascens A. L. Sm.—Thallus effuse, whitish, thin 
or evanescent. Apothecia very small, plane and with a proper 
margin, becoming convex, tawny-ferruginous (KK + purple); spores 
as in the species.—Lecanora ferruginascens Nyl. in Bull. Soe. 
Linn. Norm. sér. 2, vi. p. 260 (1872): Cromb. in Grevillea xviii. 
p. 45 (1889) & Monogr. i. p. 377. 
Easicc. Johns. n, 105. 
