PHYSCIA. | PHYSCIEL. 309 
f. 71c.—Brit. Evs.: Mudd, n. 83; Leight. n. 370; Cromb. n. 51; 
Larb. Lich. Hb. n. 48. 
Well characterized by the thinner, more adnate thallus, the shorter and 
marginally sorediate laciniz, and the smaller apothecia with their usually 
sorediate thalline margin. These characters, more especially the soredia, 
which are sometimes very abundant and obliterate the laciniw in the 
centre of the thallus, make it a distinct subspecies. In our specimens 
the apothecia, which are central, are not often present ; and the spermo- 
gones, which are similar to those of the type, are also but rarely seen. 
Hab. On the trunks of trees, rarely on old walls, in maritime, lowland, 
and upland cultivated tracts.—Distr. General and common in most parts 
of England ; apparently rare in Scotland and the Channel Islands; not 
yet with certainty gathered in Ireland.—B. M.: Island of Guernsey. 
Saham Wood, Norfolk; near Bury, Suffolk; High Beech, Epping 
Forest, Essex ; Basingstoke, Kent; Glynde, Sussex; Lymington, Hants ; 
Ryde and Appuldurcombe, Isle of Wight; near Cheltenham and Ciren- 
cester, Gloucestershire; Edgeware, Middlesex; near Elstree, Herts; 
Pampisford, Cambridgeshire; near Adderbury, Oxfordshire; Malvern 
and near Kempsey, Worcestershire; Harboro’ Magna, Warwickshire ; 
Ludlow Park, Shropshire; Aberdovey, N. Wales; Carlton, Cleveland, 
Yorkshire; Windermere, Westmoreland. Appin, Argyleshire; Blair- 
drummond, near Stirling ; Glen Ample, Perthshire ; Drum, near Aberdeen. 
Subsp. 3. P. muscigena Nyl. Syn. i. (1860) p. 418.—Thallus de- 
pressed at the circumference, more or less ascending in the centre, 
livid-chestnut or cervine-brown, usually czsio-pruinose ; lacinis 
somewhat short, dilated and discrete (K_,CaCl_). Apothecia with 
the thalline margin crenate ; spores 0,024-30 mm. long, 0,011-15 
mm. thick.—Cromb. Grevillea, xv. p.’78.—Physcia pulverulenta var. 
muscigena Leight. Lich. Fl. Suppl. p. 479, ed. 3, p. 186. Parmelia 
muscigena Ach. Lich. Univ. (1810) p. 472. 
Distinguished by the laciniz, the crenate margin of the apothecia, the 
smaller spores, and the nature of the habitat. These differences, however, 
are scarcely sufficient to warrant our regarding it, with some older and 
more recent authors, as a distinct species, but only as a well-marked sub- 
species of this very variable plant. In the only British specimen gathered 
the apothecia, which are elsewhere very rare, are not present, nor are the 
spermogones visible. 
Hab, On decayed mosses on the ground in a subalpine region.— Distr, 
Found only on the summit of one of the Central Grampians, Scotland — 
B. M.: Craig Tulloch, Blair Athole, Perthshire. 
11. P. subdetersa Nyl. Flora, 1878, p. 344.—Thallus orbicular, 
moderate, pale-cervine, subnaked or here and there yellowish-sore- 
diate ; lacinie somewhat short (K—); medulla yellow (K+ deeper 
yellow). Apothecia unknown. 
Well distinguished from P. pulverulenta var. detersa Nyl. (which has 
not occurred with us) by the colour of the medulla, It approaches 
P. enteroxantha Nyl., a Pyrenean plant, but differs in not being white- 
pruinose and in the medullary reaction. It is never seen fertile, 
