Clare Island Survey. 



14 

 LICHENES. 



By ANNIE LOKRAIN SMITH, F.L.S. 



Read June 26. Published August 21, 1911. 



The territory selected by the Glare Island Survey Committee for their study 

 of its flora and fauna extends from Achill southwards to Killary Harbour, 

 with the islands lying off the coast, and, on the landward side, includes Louis- 

 burgh, Westport, and Castlebar. It is a region of rock and moorland, the 

 uncultivated and barren tracts affording just the undisturbed conditions 

 necessary for the growth of lichens. 



The rocks of the district belong to the older series — Silurian and others — 

 and are described elsewhere; there are, in addition, areas of limestone at 

 Westport and again at Castlebar with a lichen-flora very distinct from that 

 of the siliceous rocks. Calcareous species were also found sparingly over the 

 whole district on walls where mortar had been used in building. Clare Island 

 itself, the largest of the islands and typical of the others, is formed likewise of 

 the older rocks, and presents a rugged, storm-beaten coast on the northern 

 and western sides, facing the Atlantic with high, precipitous cliffs, but sloping- 

 down towards the eastern or landward side to a boulder-strewn shore. 



Over the island the rocks are covered by grass, moor, and bog ; but often 

 they are denuded of soil, and lie exposed to sun and wind — ideal situations for 

 lichens. Towards the north-west side of the island, the ground rises to over 

 1500 feet above sea-level, but the upper reaches of the hill are boggy, and do 

 not afford foothold for purely alpine forms. There is a small patch of wood- 

 land in the most sheltered part of the island on the north-eastern side. It 

 consists of stunted trees and brushwood about 10 feet in height; and a fair 

 number of " tree " forms were found on the trunks and branches, mostly 

 Graphideae, Opegrapha atra and Graphina anguina being the two commonest 

 species. 



In the Achill and Mulranny district rock-specimens abound — some of 



them of a more or less alpine character on the higher reaches of the hills. 



Croaghpatrick, near Louisburgh, which attains a height of 2510 feet, was 



also searched. The prevailing rock is quartzite, and was found to be 



J?. I. A. pkoc, vol. xxxi. A If 



