698 Proceedings of the Royal Irish Academy. 



descends to sea level on the coast, usually ceasing at about 700 to 

 1000 feet and upwards. In Donegal it rarely descends lower than 

 about 2000 feet. Its general range is thus diametrically opposite to 

 that of the alpine group, and is more properly classed with the 

 Atlantic or Western t3rpe. 



Lest it should be thought that I haye crowded in notes of heights 

 at random, I would ask leave to give the motives which usually guided 

 me in making the records. They are either to ascertain — 



1 . Upper and lower limits of alpine plants. 



2. Upper limits of all species occuning on the mountains. 



3. Unusually high or low elevation for any plants, outside their 

 apparent normal Kmits. 



4. JS^otes on rare, local, or characteristic species. 



5. Repeated observations on plants whose range will apparently 

 prove to be very constant, and, therefore, important to ascertain 

 accurately. 



Having seen, moreover, how erroneous estimates of vertical ranges 

 are, unless taken from a wide series of observations, I have slight 

 scruples in recording what may appear to be an excess. An additional 

 reason may be given in the obvious one that inaccuracies arising from 

 a variable condition in the barometer, while observations are being 

 made, will be reduced and equalized by considering the average of 

 many records. By this means I have generally arrived at a very close 

 approximation to the truth with regard to the altitude of certain lakes . 

 The upper limits of some mountain plants are as definitely fixed as 

 the mountains themselves. 



The mountainous district examined contained 227 species above the 

 elevation of 250 feet. A few of these are, however, merely varieties. 

 The district is included in district 8 of the " Cybele Hibernica." 



The following belong to AYatson's Highland or alpine tpye: — 



Thalictrum alpinum. 

 Sedum rhodiola. 

 Saxifraga stellaris. 



S. ceespitosa. 

 S. oppositifolia. 

 Saussurea alpina. 

 Hieracium anglicum et H. 



iricum. 

 (H. gothicum.) 

 Arbutus uva-ursi. 

 Yaccinium vitis-idsea. 



Oxpia reniformis. 

 Salix herbacea. 

 Juniperus nana. 

 Carex rigida. 

 Poly sti chum lonchitis. 

 Aira alpina. 

 Asplenium viiide. 

 Lyeopodium alpinum. 

 L. selaginoides. 

 Isoetes lacustris. 



In addition to these, Dryas octopetala, Galium horede, Hieracium 

 crocatum, and Sesleria ccendea, are alpine plants occurring only at low 

 levels elsewhere in District 8, as recorded in the "Cybele Hibernica." 

 In the above list Saxifraga ccespitosa, Saussurea alpina, Aira alpina, 

 and Polystichura lonchitis are additions to the flora of this district. 



