LEPTOGIUM | COLLEMACE 79 
The strongly wrinkled and densely isidiose thallus distinguish this 
species from all others. It has not been found fertile in Great Britain. 
It has sometimes been confused with two exotic species, L. Brebrissonii 
Mont. and ZL. chloromelum Nyl. The former is less wrinkled and 
whitish- or greyish-downy beneath; the latter, an American species, 
has a subsmooth thallus. 
Hab. On the trunks of old trees and on rocks among mosses in 
maritime and mountainous districts.—Distr. Sparingly in S. England, 
N. Wales and S.W. Iveland.—B. M. Torquay, Devon; Garth, near 
Dolgelly and Barmouth, Merioneth; Eagle’s Nest and Dinish, Kil- 
larney, Kerry. 
Tomentose beneath. 
24, L. saturninum Nyl. in Act. Soc. Linn. Bord. sér. 3, i. 
p. 272 (1856).—Thallus olivaceous- or leaden-brown coloured, 
usually large, thickish, submonophyllous or polyphyllous with 
the lobes sinuate, round and entire at the margins, smooth 
or furfuraceous, beneath greyish and densely tomentose, the 
hairs sometimes fasciculate. Apothecia very rare, moderate in 
size, plane, reddish-brown, the margin thin, entire, prominent 
and cup-like; spores ellipsoid, 3-septate, becoming muriform, 
16-24 w long, 9-11 » thick.—Cromb. Lich. Brit. p. 9 ; Leight. 
Tach. Fl. p. 29; ed. 3, p. 32. L. Hildenbrandu Nyl. 1. ¢.; 
Cromb. in Journ. Bot. xii. p. 336 (1874) & Monogr. i. p. 76. 
Lichen saturninus Dicks. Pl. Crypt. fase. ii. p. 21, t. 6, fig. 8 
(1790); Sm. in Trans. Linn. Soe. i. p. 84 (1791) & Engl. Bot. 
t. 1980; With. Arr. ed. 3, iv. p. 60. Collema saturninum Ach. 
Lich. Univ. p. 644 (1810); Hook. Fl. Scot. ii. p. 71 & in Sm. 
Engl. F]. v. p. 211. C. Hildenbrandii Garov. Catal. Alc. Critt. 
ii. p. 51 (1838). Mallotium saturninum 8. F. Gray Nat. Arr. i. 
p. 399 (1821). 
Exsicc. Cromb. n. 5. 
Somewhat similar in habit to Collema furvum. In damp shady 
places the thallus often becomes blackish above when dry, contrasting 
with the light-grey colour of the under surface. The hairs in all 
the specimens tend to grow in rhizina-like strands. Apothecia are 
rather rare. 
Hab. On the trunks of old trees, generally ash, by streams in 
upland or mountainous districts.— Distr. Rather rare in N. England 
and the mountainous districts of Scotland.—B. M. Teesdale, Durham ; 
Clova, Forfarshire; Glen Lochay, Glen Lyon, Fortingall, Loch Earn 
Glenample, Craighall and Finlarig, Killin, Perthshire; Inverary and 
Appin, Argyll; Loch Linnhe and Rothiemurchus, Invernessshire. 
25. L. Burgessii Mont. in Webb & Berth. Hist. Nat. Iles 
Canar. p. 129 (1840).—Thallus greenish- or leaden-brown coloured, 
large, crowdedly lobate, the lobes somewhat imbricate, crenulate 
or lacerate and crisp, beneath greyish and more or less minutely 
tomentose. Apothecia numerous, moderate in size to large ; 
concave or becoming plane, reddish-brown or dark-red, the 
