CETRARU..] CETRARIEI. 219 



Form 2. acanthella Kyi. Mem. Soc. Cherb. v. (1857) p. 100. 

 Thallus as in the type, but very much spinuloso-denticulate through- 

 out. Apotheeia few. Cromb. Journ. Bot. 1870, p. 96 ; Leight. 

 Lich. Fl. p. 98, ed. 3, p. 93. Cornicularia spadicea y. acanthella 

 Ach. Lich. Univ. (1810) p. 612. Corcdloides fruticuli specie fuscum, 

 spinosum Dill. Muse. 112, t. 17. f. 31 B. 



Distinguished by the entirely hispido-spinulose or setulose thallus. In 

 this country the apothecia are very rare. The spermogones are frequently 

 present in herbaria specimens. 



Hab. On the ground among mosses in upland districts. Distr. Local 

 and scarce in W. and N. England, N. Wales, and among the N. Gram- 

 pians, Scotland. B. M. : Clifton, near Bristol ; Dolgelly, Merionethshire ; 

 Farndale, Yorkshire ; Prestwick Carr, Northumberland. Clova Mts., 

 Forfarshire ; Hill of Ardo near Aberdeen, S. of Lochnagar, Braemar, 

 Aberdeeushire ; Glen Nevis, Inverness-shire. 



5. C. odontella Ach. Syn. (1814) p. 230. Thallus densely fru- 

 ticuloso-csespitose, depressed, narrowly laciniate: lacini* plane, linear, 

 thin, palmately ramoso-divided, spinulose at the margins, spadiceous, 

 chestnut-brown or pale spadiceous, paler at the base, or sometimes 

 blood-coloured (K~, CaCl~). Apothecia terminal, concolorous, 



the margin denticulate ; spores 0,007-010 mm. long, about 0,0045 

 mm. thick. Cromb. Journ. Bot. 1882, p. 272. Lichen odontellus 

 Ach. Prodr. (1798) p. 213. 



This usually forms minute depressed tufts, and somewhat resembles form 

 hispida of the preceding species, hut is distinguished by the plane thin 

 lacinise. The thallus closely allies it to C. crispa, from which it is, however, 

 separated by the characters given. In the only specimen found in this 

 country apothecia and spermogones are absent. 



Hab. Among mosses on rocks in alpine tracts. Distr. A single 

 specimen from the N. Grampians, Scotland. B. M. : Cairntoul, Braemar, 

 Aberdeenshire. 



40. PLATYSMA Xyl. Mem. Soc. Cherb. v. (1857) p. 100; Syn.i. 

 p. 301. Platisma, Hoffm. Deutsch. Fl. ii. 

 (1795) p. 138 pro minima parte (ut sectio Lo- 

 ba/rice). Thallus fruticulose or membranaceo- 

 dilated, erect, ascending or appressed, more or 

 less rigid, lobed or laciuiate, concolorous on both 

 sides or discolorous ; medullary layer with the 

 filaments loosely interwoven ; cortical layer more 

 or less cellular, very rarely with tubulose cavities. 

 Apothecia discolorous from thallus, marginal 

 or submarginal, rarely adnate on the back of pj 4.3 



the apices of the laciniae, the margin entire or P i atysma commix tum 

 crenulate; hypothecium colourless; spores sub- Nyl. a. Section of 

 ellipsoid ; hymenial gelatine bluish with iodine. upper portion of the 

 Spermogones marginal, globulose ; sterigmata thallus x 200. b. 

 somewhat simple or pauci-articulate j sper- ^SSf^aT 

 matia various (not cylindrical). c . Sterigmata and 



spermatia, XoOO. 



