148 LICHENES. [Parmelm. 



6. Buds powdery, scattered all over the thallus. 



25. P. lanuginosa, Ach. Thallus orbicular, substellate, pale 

 sulphur-coloured ; the lobes flattish, rotundate, crenate ; buds in 

 a whitish or sulphur coloured powder; apothecia reddish ; the 

 border powdery. Ach. L. Un. p. 465. Lichen membranaceus, 

 Dicks. Ct. Fasc. 2, p. 21, t. 6, /. 1. 



On moss on moist rocks ; not uncommon. Patches three or four 

 inches in diameter, often on the perpendicular faces of rocks, varying 

 from white to sulphur-coloured : the thallus is thin, beneath covered 

 with a bluish-black down. Apothecia hitherto unknown in Ireland. 



7. Buds, in marginal powdery clusters. 



26. P. perlata, Ach. Thallus orbicular, substellate, glaucous- 

 grey ; the lobes rounded, crenate; the buds in greyish, elongato- 

 curved, marginal clusters; apothecia substipitate, the border in- 

 flexed. Ach. L. Un. p. 458. Eng. Bot. t. 341. 



On rocks, common ; the apothecia by no means rare, near Dunkerron. 

 Thallus often several inches in diameter ; when the living plant is wet 

 the lobes assume a greener tint. The buds marginal, in bent tufts are 

 very characteristic ; they appear on the barks of the aged apothecia, 

 the border is much incurved. 



27. P. reticulata. Thallus orbicular, substellate, glaucous- 

 grey ; the lobes round, entire, rather concave, dark at the 

 edges ; the surface marked with minute, whitish, elevated, reti- 

 culated lines ; buds marginal and terminal, in coarse grained 

 glaucous-greenish-grey collections ; apothecia unknown. 



On rocks, near Dunkerron, County of Kerry ; common. Patches 

 several inches or feet in diameter, corrugated and of a dusky purplish 

 brown in the centre ; the extreme lobes rather concave. The inferior 

 surface is black and shaggy, except at the edges, where it is of a ches- 

 nut brown. Moisture renders the upper surface slightly greenish. The 

 buds are in coarser grains than in the preceding, and extend from the 

 margin towards the axis of the lobes : those grains are frequently ob- 

 served to expand into perfect fronds ; the sinuses of the lobes are ob- 

 long and somewhat jagged, whereas in P. Icevigata they are circular 

 and nearly entire, and the lobes themselves derlexed at the edges, but 

 in our plant, the erect edges cause the terminating segments to appear 

 concave. Besides, the reticulation of the upper surface distinguishes the 

 present from every other known species. The apothecia are, hitherto, 

 unknown. 



27. P. laevigata, Ach. Thallus orbicular, substellate, glau- 

 cous white ; lobes round, subcrenate, their extremities deflexed, 

 their sinuses circular ; buds in marginal, brownish, coarsely 

 powdery collections ; apothecia with the disk of a chesnut 

 brown; the border crenate. Ach. Syn. p. 212. Eng. Bot. t. 

 1852. 



On rocks, common ; with apothecia at Dunkerron, County of Kerry. 



