Knowles — The Maritime and iMarine Lichens of Howth. 87 



The belts will be taken up in the following order : — 



(1) Tlie Ramaliiia Belt. 



(2) The Orange Belt. 



(3) The Lichina Vegetation. 



(4) The Verrucnria maura Belt. 



(5) The Belt of Marine Verrucarias. 



(1) The Ramalina Belt. 



The Eamalina belt is a very wide one, stretching from just above the 

 higli-water mark of spring-tide to the tops of the highest cliffs ; it even 

 extends inland beyond our area, covering all the rooky knolls between Red 

 Rocks and Drumleok Point on the south and south-west coasts, and many 

 of the rocks facing the sea above the Oliff-walk on the east coast are also 

 covered with a stunted growth of Ramaliuas. Tlie belt is well developed 

 both in sheltered and in exposed situations, but the most extensive colonies 

 and the strongest growths are always to be found on the windy sides of the 

 hard, rough quartzite cli£Es of the south and south-west coasts. The more 

 easily disintegrated slates and shales seldom carry a good crop of Ramalinas. 

 On the drier, more sheltered and shady eastern and northern coasts the 

 Ramalina gi'owths, though widespread, are usually sparser, and the tufts 

 more stunted and less healthy-looking. 



On the Howth coast the Ramalinas grow in two well-marked zones, those 

 of the lower zone being usually very fertile, the plants consisting of straight, 

 stiff, simple or slightly branched fronds of a pale grey-green or straw colour; 

 while the Ramalinas of the upper zone are usually barren, have much- 

 branched fronds of a darker colour than those of the lower zone, and of a 

 somewhat glaucous appearance, the extreme tips of which are incurved. 

 The paler colour of the lower Ramalinas is no doubt to some extent 

 due to the fact that they grow on rocks and boulders along the verge of 

 high-tide mark, or at a similar level on the cliffs, where they are frequently 

 splashed by spray, and washed free from dust and other extraneous matter 

 The upper Ramalinas growing on the cliffs beyond the ordinary spray-zone, 

 or on the land sides of rocks and boulders of the beach, do not come under 

 this cleansing influence, and their darker colour may be partly due to dust 

 and particles of earth, &o., accumulating on the surface of the thallus. The 

 glaucous appearance of the upper Ramalinas is, however, very distinct. 



So far as one can judge in the field, the Ramalinas of the lower zone all 

 belong to B. scopulorum. M. scopulorum is, however, morphologically similar 

 to B. cuspidata, and can only be distinguished from it by treatment with 

 hydrate of potash, when It. scopulorum gives the reaction medulla yellow, then 



SOIENT. PROO. R.D.S., VOL. XIV., NO. VI. 



