442 Proceedings of the Royal Irish Academy. 



uni'ayel the problem, and I need therefore only briefly state the views 

 current among the leading naturalists, who have given some thoughts 

 to it. 



Prof. Forbes (33 r/, j)- 14) believed, as already mentioned, that the 

 south-western Lusitanian flora is not only the oldest, but that much 

 of it survived the supposed severity of Pleistocene climate in Ireland. 

 Next in age, comes the northern or Arctic flora, which he held to be 

 glacial (p. 11), and finally the great mass of the fauna and flora 

 migrated to Ireland, in post-Glacial times (p. 10). The deficiencies in 

 the Irish fauna of certain Mammals and Reptiles met with in Great 

 Britain, he explained by the assumption that the migration of the 

 species less speedy of diffusion was aiTestedby the breaking up of that 

 land-passage which united the two islands. The latter explanation 

 has been adopted by almost every naturalist since. 



Prof. Leith Adams treats of the Mammalia only, but I presume 

 his observations apply to the whole fauna. He thinks (1^, p. 86) 

 they migrated from Scotland into Ireland during post-Glacial times. 

 " The absence of the slow-travelling mole and other local species," he 

 says, " together with the amphibian and reptilian evidence furnished 

 by Thompson, seem to me to still further strengthen the belief that 

 the land-communication between Great Britain and Ireland, at the 

 close of the Glacial Period was neither extensive nor probably of long 

 duration." 



Dr. Wallace (89, p. 338), differs from the preceding naturalists in 

 60 far as he recognizes that we possessed before the Glacial Period " a 

 fauna and flora almost or quite identical with that of the adjacent 

 parts of the Continent and equally rich in species." The submergence 

 he says, destroyed this fauna or at least the greater part of it, and the 

 post-Glacial elevation and union with the Continent cannot have been 

 of very long duration. " The depth of the Irish Sea being somewhat 

 greater than that of the German Ocean, the connecting-land would 

 there probably be of small extent and of less duration, thus offering an 

 additional barrier to migration ; whence has arisen the comparative 

 zoological poverty of Ireland." Dr. Wallace does not specify whether 

 his " we possessed'''' includes Ireland, but it is evident that he believes 

 the mass of the Irish fauna and flora to be of post-Glacial origin. 



We obtain something more definite from Prof. Boyd Dawkins 

 (22 h, p. 152), for he tells us that it is highly probable that the bear, 

 wolf, fox, horse, stag, Alpine hare, and also the mammoth and rein- 

 deer, have lived in Ireland before the Glacial Period. Whether tliese 

 became extinct during the Glacial Period and remigrated to Ireland 



