Pethybridge & Praeger — Vegetation South of Duhlin. 137 



None of these are exclusively alpine in Ireland ; and the last two are 

 frequently lowland, and in Dublin not characteristic of the mountain 

 flora. 



One table which Mr. Colgan gives is very useful for our purposes, 

 as showing the rate of decrease in the flora with increasing elevation. 

 Fig. 1 shows his facts expressed graphically, so as to exhibit at a 

 glance the features of this analysis. The rapidity of the decrease in 

 number of species as one ascends through the lower regions is very 

 marked, and easily explained. Long before 500 feet is reached, we 

 lose all maritime influence, all railways, canals, and much of the 

 effects of human industry. At 1000 feet the far-reaching influences 

 of cultivation are gone, and also the calcareous soil that results from 

 the limestone drift. Above 1500 feet man's influence is almost in 

 abeyance, though the Military lload, rising to 1610 feet, carries up 

 into the 1500-2000 foot zone no less than twenty-three lowland 

 species. Above 2000 feet only twenty-four species are left, which we 

 may list : — 



Potentilla Tormentilla. Juncus effusus. 



Galium saxatile. Luzula maxima. 



Vaccinium Myrtillus. Scirpus caespitosus. 



Y. Vitis-Idoea. Eriopborum vaginatum. 



Calluna vulgaris. E. angustifolium. 



Erica Tetralix. Carex echinata. 



Melampyrum pratense. Aira praecox. 



Rumex Acetosella. Deschampsia flexuosa. 



Enipetrum nigrum. Agrostis vulgaris. 



Listera cordata. Pestuca ovina. 



IS^arthecium ossifragum. Xardus stricta. 



Juncus squarrosus. Lycopodium Selago. 



It will be noted that this assemblage lias no marked montane facies ; 

 as Mr. Colgan remarks, it differs to only a trilling extent from the 

 flora of an Irish lowland bog. 



In studying the foregoing table and remarks, however, it must be 

 borne in mind that we are not dealing with equal areas at the different 

 elevations. AYe are comparing the flora of 329 square miles of varied 

 ground of 0-1000 feet elevation with that of 23 square miles of 1000- 

 2000 feet elevation, and of two square miles of 2000-2-150 feet eleva- 

 tion. Had we the figures showing the flora, at different elevations, of 

 a strip of ground of uniform width extending from sea-level to the 

 summit of Kippure, we could make a more instructive comparison. 



