100 Scientific Proceedings, Royal Dublin Society. , 



aud coarse quavtzites. It was not seen on tlie slates and shales. Among the 

 Kamalinas it is often associated with Lecatiora atra and Buellia ri/ssolea ; but 

 it prefers rather more shade than do these two species. Ojoegrapha calcavea 

 is most frequent where the Ramalina growths are scanty. The form 

 heteraniorpha usually grows nearer the sea than the species, and often forms a 

 wide band on steep cliffs below the Ramalinas. At Hippy Hole it grows in 

 tliis way unassociated with any other species, the blackish fruits so close 

 together as to visibly darken the surface of the rock. On these cliffs the 

 Opegrapha growth is a couple of yards high in places, and recognizable from 

 some distance off. Further west behind the Needles this lichen forms 

 similar colonies, and is here associated with Verrucaria murina var. pusilla ; 

 Lichina coifiiiis was also growing at the same level in weathered holes on the 

 rock-surface. At the east end of Broad Strand tlie high boulders are entirely 

 covered with Opegrapha calcarea on the overhanging shady sides facing away 

 from the sea, Ramalina scopulovum being abundant on the tops of the rocks 

 with Opegrapha calcarea and Lecanora atra as undergrowths. On the east 

 coast Opegrapha calcarea is also abundant ; but it generally grows below the 

 Ramalinas. On the harbour wall it forms a narrow band above the 

 Placodiums. 



Lecanora atra usually grows nearer the sea than L. parelkt. It is one of 

 the most abundant species met with among the Ramalinas, and is often 

 found on rocks where it is wetted by sea-water. Its most usual habitat on 

 the Howth coasts is on the shady side of sloping rocks, where the Ramalina 

 tufts are sparse. Plate VI sliows some colonies of Lecanora atra and Buellia 

 ry&mlea in the Ramalina scopitlorum zone at Old Boat-liouse. 



Buellia colludens, B. stellulata, Lecanora smaragdula, and L. simplex 

 f. strepsodina are other species that are common as subvegetation in the 

 Ramalina belt. They are more often met with on rather steep sunny cliffs ; 

 as a rule they avoid the quartzites, and are common on the shales and 

 schists. 



The species that seem to be more or less confined to the upper part of the 

 Ramalina belt are Lecanora glaucoma, L. polytropa Rhizocarpon geographicimi, 

 Lecidea rivulosa, L. contigua, and Pertumria concreta f. Westringii. Tliese 

 are mostly alpine forms. Lecanora glaucoma, L. polytropa, and Rhisocarjwn 

 geographieum are always associated on the south and south-west coasts ; they 

 seldom penetrate more than a little way into the Ramalinas, tliough at 

 Red Rocks and at Lion's Head one or two patches were seen on the rocks of 

 the shore; these, however, may have been on the rocks before they were 

 dislodged from the cliffs above. On the east, and more especially on the 

 northern coasts, Rhizocarpon geographieum, Lecanora glaucoma, and Pertusaria 



