120 Scientific Proceedings. Royal Dublin Society. 



with but not so often. Biatorina contridans is very rare aud only grows in 

 the damper and shadier places ; while Bacidia umbriiia, though occasionally 

 found amongst the mosses, is more usual on bare ground associated with 

 Lecanora epixantha and Acai-os2}ora henedarensis. 



At various places along the south-west coast, where the soil is hard and 

 caked, Lecidea cocuxtata var. glebulosa frequently forms patches of considerable 

 size by the paths. 



Quite a different set of lichens grow on the slopes at Q-leuaveena. 

 The soil on these banks is darker tliau at Earlscliffe, and contains marine 

 shells (glacial fossils) and a good deal of other calcareous matter. Lime- 

 loving species both of flowering plants and lichens are common, especially 

 on the lower slopes. Bracken and short coarse grass clothe the upper reaches ; 

 but lower Geranium sanguineum, Viola hirta, Carlina vulgaris, Chlora 

 perfoliata, and Poterium Sanguisorha are common. The three mosses Weissia 

 rupestris, Brachythecium p/umosuni and Pottia Heimii are also abundant. 

 Amongst tliese mossy growtlis and on bare ground Dennatocarpon hepaiicum 

 is very widespread. Its squamules, which are in all stages of develop- 

 ment, in the young stages, with their upturned edges, look very like the 

 apotliecia of some other lichen growth ; associated with it are Bilimbia 

 aromatiea and Biatorina coer ill eo nigricans, the latter exceedingly abundant, 

 the white pruinose thallus and apothecia being very conspicuous. Here and 

 there on some of the mossy tufts Lecanora hiteoalba is sometimes seen ; and 

 L. aiirantiaca var. erythrella is occasional on the bare soil. Numerous patches 

 of dark Oollemas are frequent amongst the sliort grasses by the path, C. 

 pulposum and C. cristata being the most general species, but the former was 

 seldom fertile. In damp shady places near the foot of the cliffs Cladonia 

 2ningens and C. furcala form large patches, and Cladonia dcformis is also 

 occasionally seen. The Peltigeras are very rare all round the Howth coasts, 

 thougli fairly common inland. The only species noted were P. rufescens 

 on shady grassy banks at White Water Brook and one or two plants of 

 P. canina along the east coast. 



At the base of the earthy cliffs multitudes of small stones and chips of 

 rock form a sort of talus, and occur either embedded in the soil or more or 

 less covered by the soil washed down from above. On the exposed parts of 

 these stones numerous species may always be looked for, Bueliia myriocarpa, 

 B. verruculosa, B. colludens, B. stellulata, B. confervoides, Binodina exigua, 

 Lecanora Hageni, L. cremilata, L. subfusca var. campestris, L. mteUina, L. 

 caesiorufa, Verrucaria nigrescens, Porina chlorotica, &c. Lecanora simplex 

 f. strepsodina, Acarosporas maragdula, and A. fuscata are also frequent on 

 the schistose rocks, generally occurring along the lines of the fissures or 

 outlining any unevennesses of the surface. 



