426 Proceedings of the Royal Irish Academy. 



XX. — Eeport on the Botany op Lotjgh Allen", and the Sleeve- 

 ANiEKiN Mountains. By Samtjel Alexander Stewart, Pellow of 

 the Botanical Society of Edinburgh, Curator of the Collections in 

 the Museum of the Belfast JSTatural History and Philosophical 

 Society. 



[Read, January 26, 1885.] 



LoTJGH Allen may be reckoned amongst the principal Irish lakes. 

 Its general form is somewhat pear-shaped, the extreme length from 

 north to south being nine miles, the breadth varying from three miles 

 at the north to less than one mile at the southern end. The lough is 

 shut in, on the east side, by the Slieveanierin range of mountains, the 

 highest point being Slieveanierin, in the county Leitrim, 1922 feet. 

 Slievenakilla, which is on the boundary of the counties Cavan and 

 Leitrim, has an elevation of 1793 feet. On the west side the lough 

 is bounded by the low hills of the Arigna range, which lie in the 

 counties of Cavan and Eoscommon. On this side the slopes rise 

 steadily for a distance of one to two miles from the shore, and culmi- 

 nate in a ridge, the highest points of which are over 900 feet. The 

 surface of the lake has an elevation of 160 feet above the sea. At the 

 extreme north the Upper Shannon pours into the lough, from the 

 county of Cavan, as a rapid, though unimportant mountain stream. 

 Here it is augmented by the numerous rivulets which drain the sur- 

 rounding hills, so that it flows out at the south, near Drumshambo, as 

 a deep bu.t rapid river. At Ballantra, at the margin of the lake, is the 

 old Shannon Bridge, over which the French forces under General 

 Humbert passed in 1798, and which they ineffectually endeavoured to 

 blow up in order to prevent pursuit. The damage thus done was not 

 repaired, but a new road and new bridge being constructed, the old 

 bridge has been allowed to remain in its dilapidated state, an object of 

 greater interest than the much better modern structure. The violence 

 of the wind is often severely felt on Lough Allen, and the occasional 

 squalls which surge through the narrow passes of the encircling hills 

 are sometimes dangerous. The extent of the district now reported on 

 is, roughly stated, twelve miles in length, and six in breadth, an area 

 of some seventy-two miles, about one-fourth of which is under water. 

 A very large percentage of the land is occupied by boggy heaths, and 

 another large portion by wet pastures. A comparatively small part is 

 in tillage, and this mainly around the margins of the lake. To the 

 south, near Drumshambo, limestone rocks predominate, and afford a 

 better soil. The mountain streams have cut deep gorges in the hills, 

 forming gloomy ravines, whose sides alternate with wet sandstone 

 ledges, and black crumbling shales, and are but slightly relieved 

 by displays of wild flowers, or of graceful native shrubbery. Un- 

 less for the sportsman, the scene is uninviting in the extreme, and 

 little pains are taken by the people to improve it. Only in rare in- 



