MAMMALIAN FAUNA OF NORTH CARDIGANSHIRE. 323 



it exhibits the sparse vegetation characteristic of such regions. 

 Its treeless, and for the most part trackless, surface bears 

 numerous patches of (sometimes treacherous) bog, and occasional 

 llyns or tarns. Many streams have their source on the High 

 Plateau, and flow in all directions. The valley sides often bear 

 a good deal of timber. 



One especially wild portion of the High Plateau must, be 

 mentioned here, although the greater part of it lies far to the 

 south of the district herein called; North Cardiganshire. This 

 tract is especially noted because it would seem to have an im- 

 portant bearing on certain peculiarities in the local mammalian 

 fauna, which will be described in another place. This great 

 barren tract is one of the wildest districts to be found within the 

 confines of the British Isles. It may be located as lying between 

 the village of Ystrad Meurig and Ehayader on the north, and 

 Lampeter and Llanwrtyd Wells on the south. The area of this 

 portion of the High Plateau is approximately 350 square miles. 



The land in the neighbourhood of Plynlymon is, if anything, 

 still more rugged and wild than the tract just described, but it is 

 of less importance faunistically. Here great stretches of peaty 

 soil are found, which bear only the very sparsest covering of 

 vegetation. These conditions are not suited to some mammals 

 upon the presence of which depend other species (see under 

 Rabbit in list of species). Much of the western edge of the High 

 Plateau has been altered in the search for lead, and this has 

 also resulted in the making of some fair roads. The ponds in 

 the vicinity have in many cases been adapted to supply power 

 to the mines. 



The High Plateau descends fairly abruptly to the Coastal 

 Plateau, forming the whole of the remainder of the land surface, 

 and extending to the coast. The height of the Coastal Plateau 

 stands fairly uniformly at 500 ft. above 0. D., and, except where 

 it is interrupted by river-valleys, it meets the sea in well-marked 

 cliffs. The edge of the High Plateau, and the whole of the 

 Coastal Plateau, are broken up by numerous deep valleys, those 

 north of Aberystwyth running generally due east and west. 

 The valleys are in some cases fairly well wooded, but the woods 

 are for the most part without dense undergrowth, though for 

 some few of the woods this statement needs some modification. 



