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May, 1917. The Irish Naturalist. 73 



THE MUSCI AND HEPATICAE OF THE GLEN OF 

 THE DOWNS, CO. WICKLOW. 



BY DAVID M'ARDLE. 



(plates I. II.) 

 (Read before the Royal Irish Academy, January 8, 1917). 



The Cileii of the Downs Hes in the north-east corner of 

 Co. Wicklow, five miles due south of Bray, and two and a 

 half miles from the nearest sea at Greystones. It is a glacial 

 " dry gap," a mile in length and about 400 feet in depth, 

 cut through a low ridge, 'some 700 feet high, formed of the 

 Cambrian slates of the neighbourhood. West of the glen 

 at a distance of about a mile, the ground rises to over 

 1,200 feet. Some miles further west rise the high granite 

 hills of the main Wicklow chain. The sides of the glen 

 are steep, with large detached masses of rock resting in 

 places on the slopes. The bottom has a gentle slope towards 

 the south-east, and is occupied by an insignificant stream, 

 and also by the main road from Dublin to the south. The 

 glen is densely wooded, the trees selected evidently with 

 a view to develop autumn tints, and the colours of the 

 foliage are then worth going to see. Some very fine speci- 

 mens of the Sessile-flowered Oak, with Pyrus Aucuparia, 

 Alder, Larch and Abies, Pinus, Ash and Horse Chestnut 

 occur. The conifers attain large dimensions. 



The Glen of the Downs has been better known as a pleasure 

 resort than as the haunt of the cryptogamic botanist, 

 previous records of Mosses or Liverw^orts from it being 

 very few. This was the place selected by the members of 

 the Dublin Microscopical Club for their annual excursion 

 in June, 1911 ; the day was wet and stormy, and little 

 collecting was done ; Messrs. Allen and Gimn agreed with 

 me to return in more favourable weather and investigate 

 the Musci and Hepatic ae ; we visited it in the following 

 August, and the result of our collecting was so encouraging 

 that we have paid several visits through the following years, 

 1912-13-14, always finding some Mosses or Hepaticae of 



