180 



Proceedings of the Royal Irish Academtj. 



Plate Yin. 



Typical Ulex Gallii ground, on the west slopes of Two-rock 

 Mountain, looking up GlencuUen. The soil is a thin, peaty one, on 

 granite. The tops of the distant hills (granite) are heather-clad 

 ( Calluna). 



Platk IX. 



Source of the Glendhu stream (1800 feet). Showing a large 

 stretch of Scirpus bog (SC.) in which is a considerable admixture of 

 M'iophorum angustifolium. Along the drainage channels in the middle 

 foreground, and on the steeper hill-side in the left-hand top corner, is 

 Calluna moor (C). 



Plate X. 



A Racomitritm moor on Glendhu Mountain (1900 feet), looking 

 eastwards. The general mass of vegetation is Calluna^ with a good 

 deal of Scirpus ccespUosus, and some cotton-grass (CS.). The 

 Racomitrium masses (E.) growing on the western exposed faces of the 

 peat islands and peninsulas are a conspicuous feature. 



Plate XI. 



Pig. 1. — Thorn-tree ( Cratcegus) on the slope of Tibradden Mountain, 

 about 800 feet elevation. The slope is towards the north-west. The 

 growth of the tree is greatest towards the north-east, in which 

 direction the sea lies. It is the west and south-west winds from the 

 Central Plain that here impede vegetation. On the easterly slopes of 

 the hill no such marked effect is seen as a result of winds from the 

 sea. 



Pig. 2. — Denuded peat, at 1500-1700 feet, on the northern slope 

 of Glencullen Mountain. Large areas have been cleared of j)eat by 

 the wind and rain to a depth of 4 to 8 feet, forming barren wastes of 

 bare peat, or exposing the old floor of weatliered granite. In places 

 stools of peat, crowned with Calluna^ standing up, show the amount 

 of the denudation. 



