440 Proceedings of the Royal Irish Academy. 



coast of Prance. That flora migrated, therefore, along the ancient 

 sea-border from the south, across the south-west of England, or the 

 land that lay beyond it. (See map, fig. 2.) 



Another feature in the physical geography of Ireland, which is 

 worth mentioning, is that there seems to be some reason for supposing, 

 as Mr. Close has pointed out (17, p. 242), that the west coast was 

 formerly higher, relatively to the east, than it is now. 



By means of these data we can, therefore, construct the annexed 

 map, showing approximately the geographical conditions of Ireland 

 at the time when the earliest migrants reached the country from the 

 south. 



Under such geographical conditions as prevailed in ancient Ireland 

 any animal could have walked, or any plant could have progressed, 

 on terra Jirma, from the north of France to Ireland, across the south 

 of England. True, the large river, which emerged from the southern 

 end of the lake referred to above, might have arrested their progress 

 to some extent, but probably much less than a bog or a series of hills 

 might have done. A river, as a rule, changes its course frequently 

 in the course of time, and large slices of country which formed the 

 left bank may, in this way, be suddenly transformed into the right, 

 with their fauna and flora, without any effort on the part of the 

 animals or plants. They also had the option apparently of traversing 

 England northward, and entering Ireland from Scotland. Prof. Leith 

 Adams (la) and Mr. Alston (3) believed that all the Irish Mammals, 

 and Prof. Geikie thinks that many of the smaller ones, may have 

 adopted this more circuitous route. The range, however, in Ireland 

 of the southern fauna points emphatically to its having entered that 

 country from the south, and not from tlie north. A very large 

 number of the southern animals are altogether absent from Scotland, 

 and become scarcer as we proceed north in Ireland. 



The northern animals and plants undoubtedly came across from 

 Scotland, and in the county of Londonderry, which part of modem 

 Ireland they first touched, they still are more common than in any 

 other portion of the country. But they did not originate in Scotland. 

 Under the present geographical aspect of Great Britain they could 

 only have come from the south. The majority of the northern 

 animals and plants not being known, however, south of JSTorthern 

 England, throws doubt upon such a view. We might suppose 

 that they arrived in the south, when the climate was colder, 

 and that they were exterminated in the present more unsuitable 

 climate of Southern England, while they suiwived in Scotland. The 



