LEPTOGIUM. | COLLEMEI. 75 
species, viz. Z. Brebissonii Mont., and L. chloromelum Nyl.; but it is quite 
distinct from both. According to Nyl. (tn hitt.), L. Brebissonii has the 
thallus less plicatulo-corrugate, and is moreover whitish- or greyish- 
downy beneath; while L. chloromelum (an American species) has the 
thallus:and receptacle less corrugate, the latter being subsmooth. The 
specimens found in this country are sterile. 
Hab. On the trunks of old trees and on rocks among mosses in mari- 
time and mountainous districts.— Distr. Sparingly in N. Wales and S.W. 
Ireland.—B. M.: Garth, near Dolgelly and Barmouth, Merionethshire. 
Eagle’s Nest and Dinish, Killarney, co. Kerry. 
Subgen.4. MALLOTIUM Ach. Lich. Univ. (1810) p. 644.—Thallus 
membranaceo-lobed, cellulari-corticate above, tomentose beneath ; 
gonimia moniliform. Apothecia lecanorine; spores subellipsoid, 
murali-divided. 
17. L. saturni- 
num Nyl. Syn. i. 
(1858) p. 127. — 
Thallus large, sub- 
monophyllous and 
lobato-incised, or 
polyphyllous and 
sinuato-lobed, roun- 
ded and entire at 
the margins, olive- 
or leaden-brown, 
above smooth or 
Fig. 19. 
slightly furfurace- Leptogium saturninum Nyl.—a, Vertical section of 
: a superficial portion of the tomentose thallus, 
can eae ae x 275. 6. Sterigmata, and ¢, spermatia, x 275. 
an a ‘ 
tose. Apothecia moderate, plane, reddish-brown, thalline receptacle 
cupular and somewhat prominent, margin thin, entire; spores ellip- 
soid, 3-septate, becoming irregularly murali-multilocular, 0,020- 
22 mm. long, 0,010-11 mm. thick—Cromb. Lich. Brit. p. 9; 
Leight. Lich. Fl. p. 29, ed. 8, p. 32.—Mallotium saturninum Gray’, 
Nat. Arr. i. p. 399; Mudd, Man. p.44. Collema saturninum Hook. 
Fl. Scot. ii. p. 71; Sm. Eng. Fl. v. p. 211. Lichen saturninus Dicks. 
Crypt. fase. ii. (1790) p. 21, t. 6. f 8; With. Arr. ed. 3, iv. p. 60; 
Eng. Bot. t. 1980.—Brit. Ews.: Cromb. n. 5; Dicks. Hort. Sic. 
n. 24, 
Though elsewhere a large plant, spreading extensively with firm thal- 
lus, with us it is smaller, thinner, and less polyphyllous. In damp shady 
situations it often becomes blackish above when dry, contrasting with the 
colour of the under surface. When smaller and furfuraceous it resembles 
Collema flaccidum, from which it may always be recognized by the . 
minutely cellular cortical layer, and by the whitish down of the under 
surface. The apothecia are very rare in Britain. 
Hab. On the trunks of old trees, generally ash, by streams in upland 
mountainous districts—Dzst:. Local and scarce in the 8. and W. High- 
