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PLACYNTHIUM | EPHEBACEX 31 
bluish-black hypothallus. Algal cells Scytonema. Apothecia 
sessile, plane or convex, with a proper margin only ; paraphyses 
stoutish, unbranched, septate, thicker and dark-coloured at the 
tips; asci clavate, 8-spored; spores elongate or ellipsoid-ovate, 
1—7-septate, colourless. _Spermogones minute with cylindrical, 
straight or bent, pleurogenous spermatia. 
Placed by Crombie and some other lichenologists in or near 
Punnaria, but classified among the Ephebacee on account of the 
homoiomerous thallus. 
1. P. nigrum 8. F. Gray Nat. Arr. i, p. 395 (1821).—Thallus 
subdeterminate, brownish, minutely squamulose-coralloid, cracked 
into granular-like areolz, dark-greyish- or brownish-black ; hypo- 
thallus bluish-black. Apothecia small, plane or slightly convex, 
the proper margin eutire, internally pale-whitish ; hypothecium 
brownish in thin section; paraphyses stoutish, septate, dark- 
bluish at the tips; spores ellipsoid, 1—3-septate, 11-18 » long, 
5-7 p thick ; hymenial gelatine deep-bluish then dark-violet with 
iodine.—Lichen niger Huds. Fl. Angl. ed. 2, p. 524 (1778) ; With. 
Arr. ed. 3, iv. p. 10; Engl. Bot. t. 1161. Collema nigrum Ach. 
Lich. Univ. p. 628 (1810) pro parte; Hook. in Sm. Engl. FI. v. 
p. 207; Tayl. in Mackay Fl. Hib.ii.p. 107. Lecothecium nigrum 
Massal. Ric. Lich. p. 109, f. 215 (1852); Mudd Man. p. 175, t. 3, 
f. 65 (incl. var. fuscum). Biatora corallinoides var. fusca Hepp 
Flecht. Eur. n. 10 (1853). Pannaria nigra Nyl. Lich. Scand. 
p. 126 (1861) ; Cromb. Lich. Brit. p. 43; Leight. Lich. FI. p. 168 ; 
ed. 3, p. 154. Pannularia nigra Stiz. Lich. Helv. p. 82 (1882) ; 
Cromb. in Grevillea xii. p. 58 & Monogr. i. p. 342. 
Ezsicc. Johns. n. 254; Leight. n. 366; Mudd n. 144. 
The spores are normally l1-septate, but they vary even in one 
apothecium to 3-septate. The hypothecium is light yellowish-brown 
in thin sections, though dark in the mass. 
Hab. On calcareous rocks, mortar, and flint pebbles in maritime, 
lowland and upland regions.—Dzstr. General and common throughout 
the British Isles.—. M. Guernsey; Mt. Orgueil Castle and Gorey, 
Jersey; St. Minver, Cornwall; Paignton near Torquay, Devon; 
Shanklin, I. of Wight; Beeding and Glynde, Sussex; Shiere, Surrey ; 
near Stroud and Sapperton, Gloucestershire; Bathampton Down, 
Somersetshire; Marlborough, Wilts; Breedon Hill, Leicestershire ; 
Llanymynech Hill and Bridgenorth, Shropshire; Barmouth, Merioneth; 
Bilsdale, Cleveland, Yorkshire ; Levens, Westmoreland; near White- 
haven, Cumberland; Egglestone, Durham; Appin, Argyll; Ben 
Lawers and Craig Tulloch, Blair Athole, Perthshire; Braemar, Aber- 
deenshire ; Applecross, Rossshire; near Belfast, Antrim. 
Form psotina Hue in Bull. Soc. Linn. Norm. sér. 5, ix. p. 147 
(1905).—Thallus similar to that of the species. Apothecia 
internally somewhat paler ; spores more constantly 3-septate and 
4-cuttulate.—Collema trachyopum Tayl. in Lond. Journ, Bot. vi. 
p- 193 (1847)? Pannaria nigra f. psotina Nyl. Lich. Scand. 
