402 Rev. W. A. Leighton on the Lichens of Cader Idris. 



LIX. — NotulcB Lichenologicce, No. XV. 



Notes on the Lichens of Cader Idris, North Wales. 



By the Rev. W. A. Leighton, B.A., F.L.S. 



Cader Idris is a long mountainous range extending seven or 

 eight miles in wavy length from Dolgelley, E.N.E., to the sea, 

 W.S.W., on the southern side of the estuary of the Mawddach. 

 Its northern face is one continuous precipitous escarpment 

 rising abruptly from an extensive slope, formed by spurs or 

 lower elevations, covered with boulders and fallen stones, and 

 converted by numerous rivulets into a wet bog or morass. At 

 its north-eastern end is a small but beautiful " Cwm,'^ formed, 

 as all the others are, by glacial action, enclosing with its per- 

 pendicular precipices a small tranquil lake named Llyn Aran. 

 The stream from this lake constitutes the river Aran, which 

 flows over the moraine into the river Wnion at Dolgelley. 

 Westward of this, and about midway of the northern escarp- 

 ment, is a large sublime Cwm, immediately below the highest 

 point Cader (alt. 2929 feet), in which is a fine lake called Llyn- 

 y-Gader; and below the steep moraine which retains this is 

 another smaller lake, Llyn Gafr. Immediately opposite, on the 

 southern side of the mountain, is another deeper and more 

 terrific Cwm, with perpendicular precipitous sides surrounding 

 the lake Llyn-y-Cae, whose stream flows down the steep sides 

 of the range, joins the river in the bottom of the pass, until 

 eventually both are lost in the great lake Tal-y-llyn. Beyond 

 this, westward, the range is grassy, with gradual slopes almost 

 destitute of bare rocks. The geological formation is felspathic 

 trap and greenstone. The height of the east end is 2855 feet, 

 and of the western 2403 feet. The summit is a narrow grassy 

 ridge, with extensive patches of scattered stones at intervals. 



I arrived by rail at Dolgelley on a Monday in July 1866, 

 and quartered at the Ship Hotel, with good and clean accom- 

 modation, great civility and attention, and reasonable charges. 

 The evening only afforded a brief time for reconnoitring. 

 Tuesday morning proving showery and unpromising for ascend- 

 ing Cader Idris, I deferred fulfilling my intention until the next 

 day, in hope of more propitious weather, and so determined to 

 devote the day to a kind of home circuit in examining the shores 

 and rocks of Llyn Gwernan, a small lake two miles south-west 

 from Dolgelley, close to the turnpike road skirting the northern 

 base of Cader Idris. By the way I found on the stone walls Le- 

 cidea lithophila, Ach. (new to Wales), Parmelia perlata (L.), and 

 small quantities of Ster-eocaulon Cereolus, Borr., in fructification. 

 On the stones around Llyn Gwernan nothing notable occurred 



