226 CYCLOCARPINEE | PLACODIUM 
Differs from the variety only in the somewhat smaller apothecia, 
which sometimes remain entirely immersed (foveolate), though other 
fruits in the specimen become prominent. 
Hab. On caleareous ro¢ks in maritime and inland regions.— 
Distr. Rare in S.W. England, the Grampians and W. Scotland.— 
B. M. Bathampton Downs, Somerset; Lismore, Argyll. 
Subsp. Siebenhaarianum A. L. Sm.—Thallus effuse, thickish, 
in small patches, cracked-areolate or of scattered granules. 
Apothecia rather large, adnate, convex, at first orange-coloured 
becoming dark-olive or blackish ; hypothecium yellowish-brown ; 
spores as in the species.—Biatora Siebenhaariana Koerb. Syst. 
Lich. Germ. p. 207 (1855). Lecanora irrubata subsp. Sieben- 
haariana Cromb. in Journ. Bot. xxiii. p. 195 (1885) & Monogr. 
i. p. 388. 
An alpine lichen, distinguished by the dark apothecia. Th. Fries 
(Lich. Scand. p. 425) says that the hypothecium is in young stages 
violet-rose in colour, becoming more and more brown. I have been 
unable to verify that on our specimens; the hypothecium is some 
shade of yellow in the younger fruits. 
Hab. On mica-schist rocks.—Distr. Rare in the S. Grampians, 
Scotland.—B. M. Summits of Ben Lawers and Craig Calliach, 
Perthshire. 
Thallus blackish ; reaction with potash, crimson-purple or none. 
40. Pl. atroflavum A. L. Sm.—Thallus effuse or determinate, 
blackish, very thin or with small raised smooth warts on a black 
hypothallus (K — ). Apothecia small, plane, becoming convex, 
shining, reddish-yellow, the proper margin rather lighter coloured 
(KK + crimson); paraphyses slightly thicker and branched and 
septate at the tips; spores ellipsoid, 9-11 long, 5-6 » thiek.— 
Lecidea atroflava Turn. in Trans. Linn. Soe. ix. p. 142, t. 11, 
fig. 2 (1808); Hook. in Sm. Engl. Fl. v. p. 185. Lichen atro- 
flavus Sm. Engl. Bot. t. 2009 (1809). Lecanora scotoplaca Nyl. 
in Flora lix. p. 232 (1876). L. ferruginea f. scotoplaca Leight. 
Lich. Fl. ed. 3, p. 209 (1879). LL. atroflava Nyl. ex Zwackh 
Lich. Heidelb. p. 83 (1883) ; Cromb. Monogr. i. p. 379. 
Distinguished by the very dark thin smooth thallus, whieh is. 
however sometimes obsolete. The apothecia are sometimes very 
crowded, suggesting Pl. pyracewm var. holocarpum. 
Hab. On siliceous rocks, usually exposed flints, mostly in mayri- 
time regions.—Distr. Local and scarce in $S. and BE. England, 
N. Wales and N.W. Ireland.—B. M. Ryde, I. of Wight; Beachy 
Head and the Downs, Sussex; Lydd Beach, Kent; Barmouth, 
Merioneth ; Kylemore, Connemara, Galway. 
41. Pl. Turnerianum A. L. Sm.—Thallus thin or thickish, 
warted or areolate, dark-grey or blackish (Kf + purplish in thin 
