PLACODIUM] PHYSIACE 211 
Considered by Nylander as near to Pl. awrantiacwm var. flavo- 
virescens, but differs in the form of the apothecium (zeorine). It was 
originally collected at Arnside, Westmoreland, on quartzose rocks. 
Hab. On rocks in maritime and inland districts.—Dzstr. Rare in 
N.W. England.—B. M. Cumberland (on limestone). 
Thallus greyish-white (K + purple). 
19. Pl. cerinum Hepp Flecht. Eur. n. 203 (1853).—Thallus 
thin, scurfy or granular, greyish-white, a bluish-black hypothallus 
sometimes visible (Kf + crimson). Apothecia numerous, often 
crowded, moderate in size or rather large, up to 2 mm. across, 
bright- or dull-yellow, with an entire persistent whitish thalline 
margin (K + crimson) ; paraphyses slender, knobby and septate 
and sometimes branched at the tips; spores generally small, 
subglobose to ellipsoid, 8-16 p long, 5-9 p thick, polarilocular, 
but the central tube indistinct.— Lichen cerinus Hedw. Laub- 
Moose ii. p. 77, t. 21, B (1788); Dicks. Pl. Crypt. fasc. ii. p. 14 
(1793); With. Arr. ed. 3, iv. p. 24; Engl. Bot. t.627. Patellaria 
cerina var. cyanolepra DC. FI. Fr. ii. p. 360 (1805). Leeanora 
cerina Ach. Lich. Univ. p. 390 (1810) ; Hook. in Sm. Engl. FI. v. 
p- 190; Tayl. in Mackay FI. Hib. ii. p. 136; Cromb. Lich. Brit. 
p- 147 & Monogr. i. 380 (incl. ff. cyanolepra & albiseda) ; Leight. 
Lich. Fl. p. 220; ed. 3, p. 209 (incl. var. fusca & f. eyanolepra) ; 
ff. cyanolepra & albiseda Nyl. Lich. Scand. p. 144 (1861). 
Rinodina cerina 8. F. Gray Nat. Arr. i. p.456 (1821). Callopisma 
cerina De Not. in Mem. Reale Acad. Sci. Torino ser. 2, x. p. 389 
(1849); Mudd Man. p. 133; var. fuscum Massal. Sched. Crit. 
Lich. p. 130 (1855). 
Exsicc. Cromb. n. 60; Johns. n. 34; Larb. Lich. Hb. 
nos. 21, 167; Leight. n. 83; Mudd n. 97. 
A varied species as to the development of the thallus ; it is some- 
times almost evanescent, though the apothecial margin always 
persists. Occasionally the hypothallus is predominant (f. cyanolepra), 
so that the thallus is represented by a blackish stain, rarely it is 
almost white (f. albiseda), the apothecial margin also being white. A 
number of varieties have been recognized depending on colour changes 
in apothecia and thallus. 
Hab, On the trunks of trees and on old palings, etc., in maritime, 
inland and upland districts.—Distr. General and fairly common 
throughout the British Isles —B. M. Jersey; Guernsey; Sark; Tre- 
gawn, Withiel and Truro, Cornwall; Plymouth and Exeter, Devon ; 
near Shanklin, I. of Wight; New Forest, Hants; Hassocks Gate and 
Lewes, Sussex; Maidstone, Kent; near Colchester, Ulting and 
Widdington, Essex; near Cirencester, Gloucestershire ; Oswestry 
and near Shrewsbury, Shropshire; Anglesea; Cherry Hinton and 
near Quy, Cambridgeshire; Bilsdale, Yorkshire; Derwent Water 
and Gainford, Durham; Wansbeck, Northumberland; near Kendal, 
Westmoreland ; Largs, Ayshire; Blair Drummond and Craig Tulloch, 
Blair Athole, Perthshire; near Cork; Dunkerron and Killarney, 
Kerry ; Adare, Limerick. 
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