84 Scientific Proceedings^ Royal Dublin Society. 



During tlie last three years I have paid some attention to the liclien 

 vegetation of the Howth coasts ; and in this paper I make an attempt to 

 describe it in its ecological as well as in its systematic aspect. My account 

 is necessarily very incomplete, partly because so little has been written on 

 the subject that in an initial effort there is the fear that one may make 

 mistakes, but mainly because tlie subject is an exceedingly difficult one. 

 The fruticose and foliaceous lichens are comparatively easy to recognize 

 in the field; but the majority of crustaceous species are so minute that it 

 is not possible to identify them in nitu; and, as every specimen has to be 

 submitted to the final test of the microscope, much laborious collecting 

 and examination, involving a great expenditure of time, is necessary to 

 obtain even an approximate idea of tiieir distribution. 



Area Investigated. — A broad pathway known as tlie " Cliff- walk " 

 runs along the top of the cliffs on the east coast from the Nose to the Baily 

 Lighthouse, and there is a narrow track at similar levels on the south and 

 south-west coasts. These form the upper boundary of tlie area investigated, 

 which extends thence down the sliore as far as low spring-tide, the lowest 

 level at which lichens wore found growing. 



A detailed examination of the whole coast was impossible, and my 

 observations were made mainly at various spots on the more accessible 

 soutli and soutli-west shores. Red Rocks, the Old Boat-house, Drumleck 

 Point, the Needles, Broad Strand, and Lion's Head received special attention 

 as affording different degrees of shelter and exposure ; and large collections 

 were made at these places from different levels, which were examined 

 microscopically at home to verify notes made in the field. The same 

 procedure was followed for the places examined on the east coast, viz. : 

 White Water Brook, Gaskin's Leap, High Room Bed, and Casana. The 

 northern coast was also examined in the same way. 



Assistance. — In working out the large mass of material collected I 

 frequently sent critical specimens to Miss Lorrain Smith for her opinion, 

 and I wish here to record my indebtedness to her for the time and trouble 

 she gave to them. It has been a great satisfaction to me to have her 

 confirmation of my identifications. I am also indebted to her for suggestions 

 about new species, and for checking the measurements of those described in 

 tliis paper ; for assistance in connexion with the Ramalina attachments, and 

 for many other kindnesses received when I visited the British Museum, to 

 compare some of the Howth lichens with Crombie's type specimens. To 

 Mr. A. I). Cotton I owe thanks for notes about the algae; and I must also 

 offer my sincerest thanks to Miss N. McArdle, for the care and accuracy with 

 which she identified tlie various mosses mentioned in this paper, and for lielp 

 in collecting material on many occasions. 



