488 Proceedings of the Royal Irish Academy. 



and the Saxicava sands — there have been no great oscillations, but 

 only & gradual amelioration of climate. It is qvAte imjxjssihle to believe 

 that any warm period could have intervened between the last Arctic 

 and the present temperate conditions, vrithout leaving some notable 

 evidence in the superficial deposits of Scotland, Scandinavia, and 

 North America." In the same way, I think, there are few points we 

 can be more sure of than that the South-western European fauna and 

 flora in the British Islands is more ancient than the Siberian or the 

 Arctic. If Prof. James Geikie were right, it ought certainly to be 

 the other way round. But the evidence as to the climate in the 

 British Islands during the Glacial Period is so contradictory, the very 

 nature of that period is so complex, that few scientific subjects during 

 this centui-y have raised more angry discussions, and none have jjro- 

 duced a vaster amount of literature. That I should help to increase 

 the latter still more is to be regretted, especially as the subject is not 

 my own ; but having been led by faunistic evidence to regard this 

 vexed problem from a side from which it has hitherto received but 

 little attention, I hope I may be excused for venturing to add my 

 own views to those already known. 



The Glacial Period. 



"With regard to the climate of this period, the views of the various 

 authorities are not altogether in harmony. Those of Prof. James 

 Geikie and Mr. Clement Eeid have already been stated. Somewhat 

 similar ones are held by Prof. Kehring and many other zoologists, by 

 Prof, ^athorst and many leading botanists, and also by Prof. Penck 

 and a number of geologists, but still there is a sufficiently wide disparity 

 between their views as to the temperature necessary to produce the 

 enormous increase of glaciers all over the Xorthem Hemisphere. 

 Prof. Bonney holds that a lowering of the temperature amounting to 

 18° Fahr., if only the other conditions remained either constant, or 

 became more favourable to the accumulation of snow and ice, would 

 suffice to give us back the Glacial Period (105, p. 373). On the other 

 hand, Piof. ^s'eumayr was of opinion (63, p. 619) that the reduction 

 of temperature in Europe could not have been more than 6° C, 

 which is considerably less than 18° Fabr. The very low snow-line in 

 the British Islands, he thought, proved that even then, under the 

 influence of the Gulf Stream, a comparatively mild climate existed, 

 and in fact that the climatic conditions between the various parts of 

 Europe were about the same as now (p. 619). By compaiing the 



