I-EPTOGirjJI.] COLLEMEI. 75 



-species, viz. L. Brebissonii Mont., and L. cTiloromehcm Nyl. ; but it is quite 

 distinct from both. According to Nyl. (in lift.), L. Brebissonii has the 

 thallus less plicatulo-corrugate, and is moreover whitish- or greyish- 

 downy beneath ; while L. chluromehim (an American species) has the 

 thallus and receptacle less corrugate, the latter being subsmooth. The 

 specimens found in this country are sterile. 



Hub. 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. Apothccia lecanorine ; spores subellipsoid, 

 murali-divided. 



Leptogit 



Fig. 19. 



Nyl. a. Vertical section of 

 supcrfii ial portion of the toineutose Ihallus, 

 ^7o. b. Sterigmata, and c, spernmtia, x2?5. 



17. L. satarni- 

 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 

 slightly furfurace- 

 ous, beneath greyish 

 aud densely tomen- 

 tose. Apothecia moderate, plane, reddish-brown, thalline receptacle 

 cnpular and somewhat prominent, margin thin, entire; spores ellip- 

 soid, 3-septate, becoming irregularly murali-multllocular, 0,020- 

 22 mm. long, 0,010-11 mm. thick. Cromb. Lich. Brit, p. 9; 

 Leight. Lich. FL p. 29, ed. 3, p. 32. Mallotium saturninum Gray, 

 Nat. Arr. i. p. 399 ; Mudd, Man. p. 44. Collema saturninum Hook. 

 Fl. Scot. ii. p. 71 ; Sm. Eng. El. v. p. 211. Lichen saturninus Dicks. 

 Crypt, fasc. ii. (1790) p. 21, t. 6. f. 8; With. Arr. ed. 3, iv. p. 60 ; 

 Eng. Bot. t. 1980. .Bri*. Exs.: Cromb. n. 5; Dicks. Sort. Sic. 

 n. 24. 



Though elsewhere a large plant, spreading extensively with fiim 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 furi uraceous 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. Distr. I.oi-al and scarce in the 8. and W. High- 



