BRITISH LICHENS

LECIDEA LECIDEACE2E 53
glomerate or pulverulent (K + yellow, CaCI + orange-red).
Apothecia black, sessile, small or medium-sized, plane, marginate;
hypothecium colourless; paraphyses few, irregular, indIStinct,
vaguely dark at the apices; spores ellipsoid, small, 6-7 fL long,
4-6 I'- thick; hymenial gelatine pale-blue then sordid with
iodine.-Leight. Lich. Fl. ed. 3, 266.
Considered by Stirton to be allied to L. neglecta. Its affinity seems
rather with the L. parasema group. In the specimen (from Rb. Stirton)
m the British Museum herbarium the granules are conglomerate
and almost subsquamulose. The asci are about 35 fL long, 7 fL wide;
the paraphyses, as shown on the application of potash, are slender,
septate, branched at the tips, and end in chains of mmute globose
cells.
Hab. On old worked wood.-B. 111. Glen Loehay, Killin, Perthshire.
Recorded by Stirton also from Grantown, Inverness-shire.
84. L. dubia Turn. & Borr. ex Hook. in Sm. Engl. Fl. v.
176 (1833).-Thallus effuse subleprose, pale-yellowish-green,
extremely pulverulent or almost smooth and minutely areolate
(K + yellow, CaCI + orange-red). Apothecia black, usually
numerous, scattered or confluent, subsessile, plane, becoming
convex and immarginate, the disc smooth or granular; hypothecium
brownish; paraphyses distinct, dark-bluish-green at the
apices, the colour extendmg downwards: spores ellipsoid, 12-14 fL
long, 5-7 I'- thick; hymenial gelatine deep-blue with iodine.-Tayl.
in Mackay Fl. Rib. ii. 120; Leight. Lie-h. Fl. 263; ed. 3, 260.
lichen dubius Sm. Engl. Bot. t. 2547 (1814).
Euicc. Larb. Lich. Hb. n. 143 (as Lichen leproides); Boh!. n.
H2 (douhtful).
Closely allt(,d to L. parasema. It differs from that speCIes in the
powdery thallus and in the somewhat smaller spores. The type specimen
was renamed by Nylander L. parasema var. jlavens, and another specimen
in the Sowerby herbarium was Similarly labelled by Crombie.
Our specimens form a well· connected series m which thc surface of the
thallus varIeS from bring almost smooth to completely powdery.
They also differ from L. parasema in the larger and more crowded
apoth('eia, and from var. fiavens m the rather denser powdery thallus.
Hab. On old palmgs.-Dist. Local and not uncommon in the S.
of England, extending as far north as Cambridgeshrre.-B.lIl. Near
p, ·nzance, Cornwall; Penshurst, Kent; near Isfield, Sussex; Shere,
Burrey; Ulting and Chalk End, Essex; Hinchley, Middlesex; Great
Comberton, Worcestcrshrre; Oakmgton, Cambridgeshire; Overton near
Ludlow, Shropshire.
85. L. parasema Ach. l\Ieth. Lich. 35 (1803) pro parte; Ny!.
in Bot. Not. 1852, 175 & Lich. Scand. 217 pro parte.-Thallus
determinate or subdeterminate, thin or thinnish, granulose or
rather smooth, whitish or grey-coloured (K + yellowish, CaCI -,
K (CaCI) + orange-red); hypothaUus black, at times limIting the
thallus. Apothecia small, uf,ually numerous and crowded, at