444 Proceedings of the Royal Irish Academy. 



of an older date. This belt reaches inland several miles in some places, 

 as at Brown Hall, Lough Esk, and along the Erne to Belleek ; and to 

 it is due the presence of several lime-loving species which do not occur 

 elsewhere in the county. Moreover, the warmer and more productive 

 soil to which it gives , rise supports some species which would not 

 otherwise occur so far north ; acting, as the Derry trap-rocks do, in 

 enabling lowland species there to reach an unwonted altitude. Another 

 noticeable feature in the limestone flora is the variety of its species 

 and the small quantity of this kind of derivative soil which enables 

 them to exist. The absence of the gregarious turf -loving dominant 

 sorts of heather is also remarkable, and a chief cause of the varied 

 flora. The line of junction of limestone hills with those of other for- 

 mation is recognizable at a considerable distance (as in the neigbour- 

 hood of Ballyshannon) by this prevalence or absence of heather. 



EivEE, Een^e. 



Between Ballyshannon and Belleek, along the banks of the river 

 Erne, a noble body of water rushing over a series of limestone 

 cascades about five miles long, I gathered the following plants : — 

 Cornus sanguinea, sparingly on the right bank ; Nasturtium ampliiiium, 

 Lysimachia vulgaris, and Rumex hyd/rolapathum, more plentiful — the first 

 two on both banks. In " Cliff," the beautifully wooded residence of the 

 late Mr. T. Connolly, by the water's edge in thickets occurred Geranium 

 lucidum, Alliaria officinalis, Quercus sessili/lora, and Triticum caninum, 

 the last mentioned occurring also on the opposite or left bank. On 

 the left bank of the river, about half way and nearer to Ballyshannon, 

 Carex vesicaria is plentiful, while Scutellaria galericulata, Euonymus 

 europcBUS, Cystopteris fragilis, and other local species, occur in several 

 places. Elodea canadensis has found its way into this water, and here 

 also is the only Donegal locality for the rare fern Lastrea thelypteris, 

 where it was discovered by my friend A. Gr. More. 



LoTJGH Eske. 



This lake is about ten miles round, and most beautifully situated at 

 the southern base of the rugged, desolate cliffs of the Bluestack moun- 

 tains. Its western shores are girt with wood, which are chiefly 

 natural, as at Ardnamona, and the whole basin with its limestone 

 floor is admirably sheltered by surrounding mountains from the violent 

 storms, apparently on the increase, which visit this country. Of rain, 

 however, this valley gets more than its share. The river from Lough 

 Eske to the sea at Donegal is about the same length as that from 

 Lough Erne at Belleek. Along its banks I gathered Garex pendula, 

 sparingly in one place on the right bank, not far above Donegal, 

 Salix pentandra, TJtricularia intermedia, Viburnum opulus, Cladium 

 mariscus, Parnassia palustris, Festuca sylvatica, Carex hornschuchiana, 

 Equisetum maximum, E. sylvaticum, E. hyemale, and E. variegatum. 



