PERTUSARIA | PERTUSARIACEX 363 
10. P. reducta Stirton in Scott. Naturalist, iv. p. 28 (1877). 
—Thallus thin, cracked-areolate, greyish or greyish-brown (K + 
yellow, then deep red). Apothecia sessile, with open disc, 1 in 
each thalline verruca, brown or reddish-brown, bluish-grey- 
pruinose ; spores 1 in the ascus, 90-140 p long, 30-40 p thick. 
—Leight. Lich. Fl. ed. 3, p. 229; Cromb. Monogr. i. p. 498. 
Specimen not seen. 
“Closely allied to P. multipwncta Turn., younger spores with 
broadish epispore, mature ones with coarsely granular contents.”’ 
The only plant of this section, except P. dactylina, with the marked 
reaction with potash. Wainio has recorded it from the Philippines 
(Phil. Journ. Sci. viii. p. 104 (1913)), in a sterile condition. 
Hab. On trees in the S.W. Highlands of Scotland (Ben Brecht, 
Argyll). 
11. P. lactea Nyl. in Flora Ixiv. p. 539 (1881).—Thallus 
determinate, somewhat radiate and Placodium-like at the cir- 
cumference, generally smooth, continuous or cracked-areolate, 
more or less dotted with soralia, light- or cinereous-grey or 
whitish (K —, CaCl + red, K(CaCl) + deeper red). Apothecia 
rare, small, solitary in the verruce, the disc white, subleprose, 
the thalline margin irregular; spores 1 in the ascus, 180-205 pu 
long, 65-70 p thick.—Cromb. in Journ. Bot. xx. p. 274 (1882) & 
Monogr. i. p. 498. P. lactescens var. lactea Mudd Man. p. 272 
(1861). Lichen lacteus L. Mant. p. 132 (1767) ; Huds. Fl. Angl. 
ed. 2, p. 526; With. Arr. ed. 3, iv. p. 5; Engl. Bot. t. 2410. 
Variolaria lactea Pers. in Ust. Ann. Bot. vii. p. 24 (1794) ; 
S. F. Gray Nat. Arr. i. p. 492; Hook. Fl. Scot. ii. p. 46 & in 
Sm. Engl. Fl. v. p. 170; Grev. Fl. Edin. p. 330; Tayl. in 
Mackay Fl. Hib. ii. p. 113; Turn. & Borr. Lich. Brit. p. 62; 
Leight. Lich. Fl. p. 242; ed. 3, p. 232 (as synonym of P. velata). 
V. conspurcata Turn. & Borr. ex Hook. in Sm. Engl. FI. v. 
p. 168 (1833)? & Lich. Brit. p. 57 (1839) ? 
The thallus may spread very widely and varies in thickness ; it is 
generally very light in colour, and may be easily distinguished from 
other sorediate species by the saxicolous habitat and by the chemical 
reaction. It is rarely fertile.. The spore sizes are those given by 
Nylander. It is probable that Variolaria conspurcata Turn. & Borr. 
is a synonym of P. lactea, but it is impossible to be quite sure. 
Several specimens, labelled Variolaria conspurcata, on limestone or 
mortar from Shropshire and Derbyshire, give the same chemical 
reactions as P. lactea. They are sterile and indeterminable, but are 
probably abnormal forms owing to the unusual habitat. 
Hab. On granitic and schistose rocks in mountainous regions.— 
Distr. Somewhat rare throughout the British Isles-—B. M. Chateau 
Point, Sark ; Eridge, Sussex; Aberdovey and Cwm Bychan, Merioneth ; 
Anglesea ; Craig-y-Rhiw, Shropshire? ; Matlock, Derbyshire?; near 
Moffatt, Dumfriesshire; West Water, Forfarshire ; Ben Lawers and 
Craig Calliach, Perthshire; Portlethen, Kincardineshire; Glen Ey, 
Braemar, Aberdeenshire ; Blackwater, Kerry. 
