12 LLOYD'S NATURAL HISTORY 



mitted the whole of the post-glacial continental Mammals to 

 have reached Britain. And he adds that if it can be shown 

 that the continental forms missing from our present fauna are 

 those most likely to have been exterminated by the cold, or 

 least likely to cross the separating sea and if, in addition, they 

 are species calculated to migrate as quickly as those which 

 are common to this country then there will be a further argu- 

 ment against the second continental period. 



Without offering a definite opinion on a question so bristling 

 with difficulties as the above, we may say that, so far as Mam- 

 mals are concerned, we do not think that anything decisive 

 one way or the other can be deduced from the considerations 

 referred to in the last sentence. If the ancestors of our pre- 

 sent Mammals did survive the whole Glacial period in the 

 south of England, there would of course be no difficulty in 

 regarding them as having repopulated England and Scotland 

 at its close. The case is, however, more difficult with regard 

 to Ireland, which, on this hypothesis, must at the same time 

 have been separated from the sister-island, since here, too, we 

 must have had an area in which the present Irish Mammals 

 survived the cold period If, however, those that now exist 

 there then survived, why did not at least as many persist there 

 as in England, seeing that the Irish climate was probably then, 

 as now, milder than that of England ? It can hardly be urged 

 that the area free of ice in Ireland was too small for all the 

 species, seeing that animals of the size of the Red Deer and the 

 extinct Irish Deer are known to have lived in Ireland within the 

 recent period, and must, consequently, on the hypothesis under 

 consideration, have been among the survivors ; it being evident 

 that an area of land sufficiently large to have supported such 

 creatures would perfectly well have also maintained such existing 

 English Mammals as are unrepresented in the Irish fauna. 



The great objection that Mr. Bulman seems to have to the 

 alleged post-glacial connection of Britain with the Continent is 



