Clare Island Survey — Mammalia. 17 11 



That Ireland is, with the exception of its Hare and Stoat, faunistically 

 more recent than Great Britain, is shown by the absence of peculiar isolated 

 local forms, such as are found in several parts of Great Britain, more especially 

 in the north. I may cite particularly the Skomer Mouse, the Hebridean 

 and Fair Island Wood Mice, the Jura and Islay Stoat, the two species 

 of St. Kilda Mice, and the Orkney Mice. There is nothing in the least 

 approaching the position of these isolated forms in Ireland. The Skomer 

 Mouse is peculiarly interesting for our present purposes, because it has a 

 near relative {E. caesarius) in the Channel Islands, suggesting that its ancestors 

 formerly inhabited a continuous tract of country stretching from Pembroke- 

 shire to France. Bemains of another member of the same group have been 

 found in the Ightham fissures in Kent, and it was one of the late pleistocene 

 mammals of Britain. It is to the area bounded or roughly marked out by Skomer 

 Island, Ightham, and Jersey, rather than to any region lying south of Ireland, 

 that we may look for the survival of our pre-glacial mammals. This is both a far 

 more extensive and more southern region than any portion of peripheral Ireland 

 within the 50-fathom line ; it requires less elevation to bring it into existence ; 

 it affords easy connexions with continental Europe at an elevation of less than 

 300 feet, at which elevation the south of Ireland would still be isolated from 

 England ; and it lies well clear of the southern limit of the maximum English 

 glaciation, which did not overrun the Thames valley, whereas Ireland was 

 heavily glaciated right down to the limits of its present southern and south- 

 western coast-line. 



If at the same time as dry land stretched from Skomer to the coast of 

 France, there was also, as there would be with a similar elevation, a bridge 

 across the shallowest part of the Irish Sea between Bardsey Island and 

 Wicklow, with a wide expanse of marshes and forest bordering a central 

 narrow strait a few miles wide running thence south to the Atlantic through 

 the present St. George's Channel, then the extreme narrowness, and marshy 

 nature of the connexion, would account for the fact that many of the English 

 mammals failed to reach Ireland. Those that did reach Ireland — the Fox, 

 Wolf, Badger, Marten, and Otter, the Bed Deer (and, perhaps, Wild Boai') — 

 are amongst the hardiest and widest-ranging species known to us, and it is 

 easier to account for their presence than their absence. Of the numerous 

 forms which did not reach Ireland, besides those which were impeded by the 

 forests and marshes, others must have only recently crossed to England ; and 

 the narrow bridge was finally closed before the latest arrivals had time to 

 find it. If a similar bridge existed contemporaneously between Malin Head 

 and Islay, it must have been impassable, as there are no close relationships 

 between the Irish mammal-fauna and that of Scotland. On the other hand, the 



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