74 COLLEMACEI. [LEPTOGITJM. 



ed. 3, p. 31. Collema tremell 'aides Hook. Fl. Scot. ii. p. 72 ; Sm. 

 Eng. Fl. v. p. 213 ; Tayl. in Mack. Fl. Hib. ii. p. 111. Lichen 

 tremelloides Linn. fil. Suppl. PL (1781) p. 450; Eng. Bot. t. 1981. 

 Lichen cochleatus, Dicks. Crypt, fasc. i. (1785) t. 2. f. 9 ; With. Arr. 

 ed. 3, iv. p. 74. Brit. Exs.: Cromb. n. 110; Larb. Lich. Hb. 

 n. 3. 



Differs from L. lacerum in the larger smoothish thallus, leaden-coloured 

 when dry, in the more rounded lobes with entire margins, and in the 

 t-levated, larger apothecia. The cortical layer is formed of rather large 

 angular cells. Sparingly fertile in S.W. England and W. Ireland. 



Hab. Among mosses on moist rocks in maritime and mountainous 

 districts. Distr. General, and usually plentiful in the Channel Islands, 

 S. and W. Britain, and E. and S.W. Ireland. B. M. : St. Peters Valley, 

 Island of Jersey. St. Lawrence, Isle of Wight ; near Brixham, Salt ash, 

 Ilaberton, Conworthy, Wembury, and Totness, S. Devon ; St. Issey and 

 near Penzance, Cornwall ; Tenby, Pembrokeshire ; Barmouth and liar- 

 lech Castle, Merionethshire; Garn, Denbighshire; Llanberis Pass, Car- 

 narvonshire ; Island of Anglesea. Dumbarton Castle, Dumbartonshire ; 

 Appin and Island of Mull, Argyleshire. Dunkerron Mt, Blackwater, 

 and Killarney, co. Kerry ; Kylemore and Doughbraugh Mts., co. Galway. 



Form polyphyllum Nyl. ex Leight. Licb. Fl. ed. 3 (3879), p. 32. 

 - Thalline lobes smaller, more divided and complicated, naked or 

 isidiiferous. 



The thallus of this polyphyllous form when densely covered with isidia, 

 as it usually is, is form pichneum (Ach. Syn. p. 343), Cromb. Grevillea, 

 xv. p. 13. Not seen fertile. 



Hab. On damp rocks among mosses in maritime districts. Distr. Local 

 and scarce in S. England, the S.W. Highlands of Scotland, and N.W. 

 Ireland.- B. M. : Near Torquay, S. Devon. Island of Mull, Argyleshire. 

 Near Kylemore, Connemara, co. Galway. 



Subgen. 3. STEPHANOPHOEUS Flot. Linnsea, 1843, p. 16. 

 Thallus crowdedly plicatulate ; apotbecia with the thalline recep- 

 tacle plicate-rugose. 



16. L. ruginosum Nyl. ex Cromb. Grevillea, xv. (1886) p. 13. 

 Thallus membranaceous, roundly lobed, plicate, longitudinally and 

 crowdedly rugose, brownish- or greenish-lead-coloured, brownish- 

 black-furfuraceous on the upper surface; lobes complicate, undulate, 

 the margins entire or crenulate. Apotbecia somewhat large, slightly 

 concave or plane, red or brownish-red, the thalline margin thick, 

 rugoso-plicate or furfuraceo-granulate ; spores ellipsoid or attenuate 

 at both apices, 3-5-scptate, and also sometimes longitudinally divided, 

 0,020-37 mm. long, 0,010-17 mm. thick. Collema ruginosum Duf. 

 in Schaer. Enum. (1850) p. 251. Leptogium chloromelum Mudd 

 (non Jf yl.), Man. p. 48 ; Carroll, Journ. Bot. 1867, p. 254 ; Cromb. 

 Lich. Brit. p. 9 ; Leight. Lich. Fl. p. 32, ed. 3, p. 32. 



This can scarcely, even in an infertile state, be mistaken for any other 

 British plant. It has sometimes been confounded with two exotic 



