PLACODIUM | PHYSIACE® : 221 
in Journ. Bot. xiv. p. 360 (1876) & Monogr. 1. p. 389; Leight. 
Lich. Fl. ed. 3, p. 224. 
Closely allied to the preceding, of which it may only be a form, 
but with larger, peculiarly developing spores. They are, however. 
truly polarilocular, and careful examination has failed to establish the 
4-celled condition. Considered by Nylander to be related to Lecanora 
Brebissonti, a S. American plant. 
Hab. On calcareous rocks in maritime and inland situations.— 
Distr. Rare throughout England and 8.W. Highlands of Scotland.— 
B. M. Near Plymouth, Chudleigh, Ilsham and above Anstey’s Cove, 
Devon; Cunning Dale, Buxton and near Bonsall, Derbyshire ; 
Malham Tarn, Yorkshire; Levens, Westmoreland; I. of Lismore, 
Argyll. 
35. Pl. vitellinulum A. L. Sm.—Thallus effuse, thin, some- 
times faintly areolate, yellowish (Kf-+ purplish). Apothecia very 
small, numerous, orange-yellow (K + crimson), the proper margin 
prominent or at length excluded ; spores oblong-ellipsoid, small, 
9-12 p long, 4-6 p thick. —Lecanora vitellinula Nyl. in Flora xlvi. 
p. 305 (1863); Cromb. in Journ. Bot. xx. p. 273 (1882) & 
Monogr. i. p. 385. 
Distinguished by the colour of the thallus and by the small spores. 
The paraphyses are slender, but often two or more large cells are 
separated off at the tips. 
Hab. On caleareous rocks in maritime and hilly districts.—Distr. 
Rather rare, but widely distributed throughout the British Isles.— 
B. M. Noirmont, Jersey; Sidmouth, Devon; Yatton, Somerset ; 
Beethwaite, Westmoreland; Overend, Egremont, Cumberland; Lis- 
more, Argyll; Carrigogunnel, Limerick. 
Thallus greyish-white ; reaction with potash various. 
36. Pl. ferrugineum Hepp Flecht. Eur. n. 400 (1857).—Thallus 
effuse, very thin or thickish, and unequal or areolate, greyish or 
whitish, sometimes evanescent (K + purplish). Apothecia small 
or moderate in size, plane, becoming convex, bright rusty-red 
(K + purple), the proper margin thin, rather lighter in colour, 
prominent, sometimes flexuose ; paraphyses septate and branched 
upwards, and capitate ; spores broadly ellipsoid, 11-16 yp long, 
6-11 p thick.—Lichenoides leprosum, tuberculis fuscis et ferrugineis 
Dill. Hist. Muse. p. 126, t. 18, fig. 4 (1741) pro parte. Lichen 
ferrugineus Huds. Fl. Angl. p. 444 (1762); Engl. Bot. t. 1650. 
L. vernalis Lightf. Fl. Scot. ii. p. 805 pro parte. Lecanora 
ferruginea Nyl. in Act. Soc. Linn. Bord. sér. 3, i. p. 322 (1856) ; 
Cromb. Lich. Brit. p. 46 (corticolous) & Monogr. i. p. 376 ; 
Leight. Lich. Fl. p. 219; ed. 3, p. 208 (corticolous). Callopisma 
ferrugineum Mudd Man. p. 139 (1861). 
Exsicc. Bohl. n. 108; Larb. Lich. Hb. n. 95. 
The thallus is variable, but the species is well distinguished by the 
persistent rusty-red colour of the apothecia. Occasionally the thallus 
