Hah. On rocks in high latitudes.—Disir. Somewhat rare.—E. M.
Agron, Cleveland, Yorkshire; Tarnbrook Fell, Lancashire; Aran
Mawddwy, Merioneth ; Kylemore, Connemara, Galway ; near Killin,
Perthshire ; near base of Ben Cruachan and Ballachulish, Argyll.
Order IV. L E C ID E A C E ..f f i.
Thallus minutely squamulose or crustaceous, sometimes
obsolete; algal cells (gonidia) Chloropliycese. Apothecia discoid or
patellate with proper margin only ; spores usually eight in the
ascus, sometimes fewer or more, simple or variously septate,
colourless or coloured. Spermogones immersed; spermatia elongate,
elliptical or cylindrical.
This Order as defined above includes the Lichens classified
generally under the single comprehensive genus Lecidea by
Nylander in Mem. Soc. Cherb. v. pp. 119-127 (1837), by Leighton,
Lich. Flora, pp. 248-358, ed. 3, pp. 240-389, and by Crombie,
Lich. Brit. pp. 62-94 and in Grevillea xxii. pp. 8-11 and 57-60
(1893-4). The view held by early writers th a t the form of the
spores is a character of generic importance, has been revived
by recent lichenologists, and the species have been arranged
according to spore characters in the following order :—
Apothecia cup-like, brightly coloured, marginate.
Spores colourless, septate or muriform ........ 70. Gy a lecta.
Apothecia discoid or patellate blackish or coloured.
Spores colourless.
Spores simple.
8 or fewer in the ascus ..................... 71. L ecidea.
Many in the ascus .............................. 72. B ia to re lla .
Spores septate.
1-septate................................................... 73. B ia to rin a .
3- or pluriseptate, fusiform ............. 74. B ilim b ia .
Pluriseptate, acicular ......................... 75. Ba eid ia.
Spores brown.
1-septate........................................................... 76. B u e llia.
3-septate (parasitic)...................................... 77. L e c io g rap h a .
Spores colourless or becoming brown.
8 in tbe ascus :
Muriform (sometimes 1-8-septate
in species 1) ................................. 78. E h iz o c a rp o n .
1 in the ascus :
Muriform, la rg e ................................ 79. Bom b y lio sp o ra .
Blongate-pluriseptate, large ....... 80. L o p ad ium .
70. GYALECTA Ach. Lich. Univ. p. 30 (1810). (PI. 4 )
Thallus granular, pulverulent, or nearly obsolete; algal cells
Trentepohlia. Apothecia brightly coloured, concave, with a
prominent proper margin, somewhat urceolate-patellate; asci
usually 8- rarely many-spored; spores variously septate, or
muriform. Spermogones with almost simple sterigmata and
straight ra th e r short spermatia.
Apothecia closed a t first, the margin (exeiple) radiately
fissured (P etractis Fr. Summa p. 120 (1846)).
1. G. exanthematica Pr. Lioh. Eur. p. 197 (1831).~Thallus
effuse, very thin, continuous, greyish-white ( K - , C aC l- ) , often
obsolete. Apothecia small, immersed, pale-yellow or yellowish-
flesh-coloured, the margin white, connivent, radiately (3-6) fissured
a t length exposing the epithecium; hypothecium pale; paraphyses
slender; spores 8nate, fusiform, 3-septate, 0,015-20 mm
long, 0,006-7 mm. th ick ; hymenial gelatine pale bluish with
lodme.—Lichen exanthematicus Sm. in Trans. Linn. Soc. i. p. 81
t. 4. f. 1 (1791); Dicks. Crypt, fasc. iii. p. 14; With. Arr. ed. 3
iv. p. 22; Engl. Bot. t. 1184. Thelotrema exanthematica S F
Gray Nat. Arr. i. p. 444 (1821); Hook. FI. Scot. ii. p. 45 and
in Sm. Engl. FI. v. p. 161 _; Leight. Angio. Lich. p. 32, t. 12.
Hib. ii. p. 103. Lecidea exanthematica
Nyl. in Mem. Soc. Cherb. v. p. 119 (1857); Cromh. Lich. Brit p 62 •
Leight. Lich. FI. p. 334; ed. 3, p. 355. Petractis exanthematica
hr. Summa p. 120; Mudd Man. p. 278, t. 5. f. 117.
Lxsicc. Leight. n. 256.
A very typical lichen, which has been referred by authors to several
distinct genera and even tribes. I t has frequently been regarded as
Ihelotrema, but, as Nylander observes (Mem. Soc. Cherb. t. iii.
p. 181 nota), the hypothecium presents in the texture of its lateral
portions no jointed filaments. The peculiar apothecia are characteristic
of Gyalecta; they are at first closed, appearing as if verru-
canoid, b-at at length become disciform, often disappearing in age
leaving numerous whitish depressions or pits on the substratum. ’
Hah. On calcareous rocks and cretaceous stones in upland, rarely
maritime, tracts.—Distr. Not uncommon in England, rare in the S W
Highlands of Scotland and in the N. and S. of Ireland.—S . M Shiere'
Surrey; Mount Harry, Fulking, and the Downs, Sussex; Torquay
and near Babbicombe, Devon ; Park Corner, Cirencester, Gloucestershire
; Cunning Dale and Deep Dale, Buxton, Derbyshire; Eglwyseg
Rooks, near Llangollen, Denbighshire; Ingleborough, Yorkshire-
Eglestone and near Barnard Castle, D u rh am ; Levens, Westmoreland ’
Lamplugh, Cumberland; Achosragan Hill, Appin, Argyll; near
Belfast, Antrim; Kylemore Castle, Connemara, Galway; Killarney,
Apothecia subbiatorine, concave, the margin typically entire.
Spores 3- or pluri-septate and often variously divided.
2. G. cupularis Schser. Enum. p. 94 (1850).—Thallus effuse,
very thin, continuous, subleprose, whitish or pale-greyish
~ ) CaCl — ). Apothecia moderate, superficial and prominent;
epithecium impressed, concave, flesh-coloured or yellowish-red,
the margin thiokish, entire or a t times radiato-striate, w h itish ;
hypothecium colourless ; paraphyses slender, not well discrete;
spores 8nate, ellipsoid, 3- then multi-septate and muriform'
0,015-17 mm. long, 0,007-9 mm. th ick ; hymenial gelatine