92 Scientific Proceedings, Royal Dublin Society. 



dotted all over the quartzites, in some places sparingly, in others grouped into 

 dark masses. Some of the smallest tufts measured less than \ of an inch in 

 diameter, and they seldom exceeded \ an inch in height. Here and there 

 small erustaceous spots were to be seen which appeared to be the starting- 

 points of new tufts. 



On the south-western or sea-faces of the cliffs the plants are somewhat 

 larger, but everywhere they are closely adpressed to the rock-surface. At 

 lower levels the fronds lengthen, the growth becomes closer, and gradually 

 assumes the characters of Ramalina A. 



The conditions under which Ramalina B. grows on these steep cliffs are 

 very severe. The surface of the extremely hard and close-grained quartzite 

 retains little moisture and affords scanty foothold. The plants are exposed 

 to the full force of the prevalent winds. Except in violent south-westerly 

 gales, they are well above the spray, so that the only moisture they receive is 

 what is carried to them by the west and soutli-west winds in rainy weather, 

 or what they absorb from the atmosphere during mists and fogs, which are 

 sometimes frequent along the coast in autumn and winter. In spring and 

 summer there are often long spells of dry, sunny weather during which 

 Eamalina B. becomes very much burnt up and brittle, crumbling at the 

 slightest touch. Warming says (29, p. 240) that erustaceous lichens are among 

 the first colonizers. But on these steep rock-faces there is a complete absence 

 of any of the erustaceous species. The problem, therefore, as to how Ramalina B. 

 has obtained a footliold on these very liard precipitous rocks, which are too 

 inhospitable even for erustaceous species, is an interesting and puzzling one. 



On the south-eastern slopes the incline is gentle and the rocks are more 

 sheltered. Here the ilamalina growths are sparser, and there is a good 

 subvegetation of erustaceous lichens, BuelUa ryssolea being one of the 

 commonest species. Other Buellias, Rliizncarpon geograj)hicum, Lecanora 

 glaucoma, and L. poli/tropa also occur. On the flatter rocks where moisture 

 lies longer, foliaceous species such as Parmelia conspersa, P. fuliginosa, P. 

 saxatiUs, and others form very large colonies, extending right up to the top 

 of the hill. On the peaty soil bordering the rocky tracts, and on the bare 

 patches here and there amongst the heather and low Gorse shrubs, several 

 species of Cladonia and other earth-loving liclieus abound. 



The small amorphous Ramalina B. covers large areas at Drumleck Point 

 and at other places on the south and south-west coasts. It is essentially a 

 form of windy situations, and is characteristic of the highest and steepest 

 cliff-faces, especially of those with a westerly or south-westerly aspect. 



Ramalina C. — Tlie third form in the upper zone may be called Ramalina O. 

 It is found in shade and shelter. The thallus is rather softer in texture. 



