208 CYCLOCARPINEE [PLACODIUM 
Form luteum A. L. Sm.—Thallus very thin, pulverulent, 
pale greenish-yellow or grey. Apothecia minute, orange-coloured. . 
Lecidea epixantha var. lutea Ach. Lich. Univ. p. 209 (1810). 
Lecanora phlogina var. lutea Nyl. Lich. Scand. p. 142 (1861) ; 
Cromb. Monogr. i. p. 386. 
Differing in the generally more reduced growth, which is probably 
due to the substratum. 
Hab. On vegetable detritus in maritime districts.—Distr. Rare in 
S. England and 8.W. Highlands of Scotland.—B. M. Luccombe 
Cove, I. of Wight; Rottingdean, Sussex; Airds, Appin, Argyll. 
16. Pl. incrustans A. L. Sm.—Thallus effuse, crustaceous, 
thickish, areolate or reduced to scattered granules, pale- or 
greenish-yellow (K + purplish). Apothecia plane or slightly 
convex, orange-yellow, sometimes pruinose, the thalline margin 
entire or becoming crenulate; spores ellipsoid, polarilocular, 
&8-13(-18) p long, 4-8 p thick.—Lecanora incrustans Ach. Lich. 
Univ. p. 405 (1810); Cromb. in Grevillea xviii. p. 45 (1889) & 
Monogr. i. p. 372. 
Sometimes regarded as a variety of Pl. mwrorum; the paraphyses 
are branched above and often capitate, and their septation upwards 
well-marked as in those of that species. The description is partly 
taken from Bouly de Lesdain (Lich. Dunk. p. 133), who gives spore 
length up to 18 p. 
Hab. On schistose walls in a maritime district—B. M. Port- 
lethen, Kincardineshire. 
17. Pl. aurantiacum Hepp Flecht. Eur. n. 198 (1853).— 
Thallus subdeterminate, thickish, or sometimes very thin, with a 
spreading grey hypothallus not always visible, thinly mem- 
branaceous, continuous or areolate, pale citrine, greyish- or 
greenish-yellow (K + purplish). Apothecia small or moderate 
in size, plane, with a thin entire or crenulate margin, becoming 
convex and immarginate, deep orange or reddish; paraphyses 
clavate, septate and branched upwards ; spores broadly ellipsoid, 
varying in size and development of septum, 11—16 p» long, 6-9 
thick.— Lichen flavorubescens Huds. Fl. Angl. p. 443 (1762)?; 
With. Arr. ed. 3, iv. p. 15? L. aurantiacus Lightf. Fl. Scot. ii. 
p. 810 (1777) pro parte. LL. salicinus Schrad. Spicil. Fl. Germ. 
p. 82 (1794); Engl. Bot. t. 1305 (1804), Lecidea aurantiaca 
Ach. Meth. Lich. p. 69 (1803) ; 8. F. Gray Nat. Arr. i. p. 476; 
Tayl. in Mackay FI. Hib. ii. p. 129. Rinodina salicina 8. F. Gray 
tom. cit. p. 456 (1821) (incl. var. microthelia). Lecanora 
aurantiaca Hook, in Sm. Engl. Fl. v. p. 186 (1833); Leight. 
Lich. FL p. 217; ed. 3, p. 206 (incl. var. salicina) ; Cromb, Lich. 
Brit. p. 46 & Monogr. i. p. 373. © Callopisma aurantiacum 
Massal. Monogr. Lich. Blast. p. 70 (1853); Mudd Man. p. 137 
(incl. var. salicinum). 
