HO LICHENES. [Lecidea. 



crowded, rather convex, rugged, dark-grey scales, greenish 

 when wet; apothecia very minute, conspicuous, sessile; the 

 disk black, rough, flat, at length convex; the border thick, 

 entire, at length subobliterated. 



On siliceous rocks, near Dunkerron, County of Kerry. This, like 

 the preceding, forms patches or stains on the surface of the rock, but 

 of a duskier black. The inferior black stratum exceeds at the edges, 

 and appears abundantly between the scales : these are of a yellowish- 

 green when moist, of a dusky-grey and pruinose when dry, rough with 

 elevated paler points, oblong or rotundato-angulate, not distinguishable 

 bv the naked eye The apothecia are scattered and minute, yet very 

 visible as black projecting points; the disk rougher and blacker than 

 the border, flat or convex ; the border becoming obsolete sometimes 

 from the convexity of the swoln disk. Dissection under the lens shows, 

 beneath a black rough disk, a lamina proligera striated, its upper 

 layer pale, its lower of a pale blue, beneath this is some slightly 

 brownish-white matter resting on a black substance. It may be dis- 

 tinguished from L, macula by the evident and sessile apothecia, not 

 placed each on a scale, by the appearances on dissection, and by the 

 scales being more minute and without the elevated pale border. In 

 L. prominula, Bon: the upper surface does not change its brownish 

 hue to yellowish green when moistened, is areolate, but not divided 

 into distinct scales ; the apothecia in a dry state have a more concave 

 disk, and more raised border ; the entire thallus is thicker ; the nature 

 of the lamina proligera very different. 



3. L. atro-alba, Ach. Inferior stratum of the thallus thin, 

 black, closely investing, the upper of crowded, somewhat con- 

 vex, brownish-grey, rough scales ; apothecia in the interstices, 

 larger than the scales, plano-convex, black ; the disk rough ; 

 the border smooth, entire, at length obliterated. Ach. Lick. tin. 

 p. 162. Eng. Hot. t. 2336. 



On siliceous rocks, near Dublin : also near Dunkerron, Kerry. In 

 a dry state the warts or scales of the thallus are flatter, and so aggre- 

 gated that the collection appears like portions of a crustaceous thallus 

 areolated. The patches are from one to six inches in diameter. The 

 moistened apothecia are very convex, their border scarcely to be seen, 

 their disk, from being black, assuming a dun or grey colour ; beneath 

 this is a thick, pellucid, brownish-grey lamina proligera, striated, 

 resting on brownish-black matter. 



4. L. fumosa, Ach. Substratum of the thallus tartareous, 

 thick, black, cracked ; the upper layer of immersed, roundish, 

 distinct or crowded, flat or concave scales, of a brownish-fawn 

 colour, with raised, pruinose edges; apothecia scattered, larger 

 than the scales, flat, black, pruinose ; the border thick, entire, 

 slightly waved. Ach. L. Un. p. 157. Mugeot and Nest. Or. 

 Vog. Rh.No. 461. 



On siliceous rocks ; Dunkerron ; not uncommon. Allied to the 

 preceding. Moisture applied produces no other change on the scales 

 but their more pruinose appearance especially at the edges. The apo- 

 thecia are not in the interstices as in the preceding, their border paler 

 than the -disk ; this last appears, on dissection, to be black, thick, 



