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On the neighbouring rocks was abundance of Andraja Rothii, in 

 fruit, with A. alpina in smaller quantity; also Grimmia ovata, Anic- 

 tangium ciliatum, and several species of Trichostomuin : scattered 

 here and there were Carex dioica and Splachnum sphsericum. We 

 did not stay long in this place, as the rain began to descend rather 

 heavily, but made the best of our way along the shore of the lake, and 

 up the rugged side of the mountain to Twll du. 



On the occasion of my previous visit, I ascended the course of a 

 mountain stream, and gathered the following mosses upon the rocks 

 which bordered it. Gymnostomum fasciculare, Weissia acuta, Gly- 

 phomitron Daviesii, Bryum crudura, B. julaceum, B. ventricosum and 

 B. Zierii, with many others of less note. The rocks on our way up 

 the mountain side were covered with the beautiful Silene acaulis, 

 Saxifraga hypnoides, stellaris and oppositifolia, in fruit, Oxyria reni- 

 formis and Asplenium viride. Twll du is an immense chasm or cleft 

 in the mountain, the sides of which are perpendicular. It appears to 

 have been formed by the long-continued action of a stream, which 

 runs from a small lake above, called Llyn y cwn. At my first visit, I 

 penetrated this cleft till 1 reached an immense block of stone, which 

 completely chokes the passage, rendering further progress next to 

 impossible. As our present object was to gain the top as soon as pos- 

 sible, we turned to the left on reaching the chasm, and so ascended, 

 keeping close to the wall of rocks. 



On these rocks we gathered Trollius europseus, Thalictrum alpi- 

 num, Rhodiola rosea, Arenaria verna, Gnaphalium dioicum, and a 

 Saxifrage which I suppose to be S. caespitosa ; Hypnum Crista-cas- 

 tensis and Neckera crispa grew at the base, but we found no fruit. 

 On reaching the summit, our friend the quarryman took off his load 

 of rope, to reconnoitre the place. I had to act as guide, being the 

 only one of the party who had visited the place before. We first went 

 to the channel where the little stream leaps over the rocks into the 

 profound abyss. From this place we could see plenty of the Lloydia 

 serotina growing on the face of the precipice, above the large block of 

 stone. There was one specimen bearing two flowers, a yard or two 

 from the waterfall, ahnost within reach. I had seen the same speci- 

 men before, and wished much to gather it, but the attempt would have 

 been very dangerous, from the friable nature of the rock. Fortunately 

 I saw another, vt'hich, after a little climbing, I managed to obtain. 

 We then returned to the rocks immediately above the precipice, where 

 the quarryman fastened the rope round his body, and began the de- 

 scent, having first given us strict injunctions not to let go our hold. 



