SOME THOUGHTS SUGGESTED BY MR. BATH's PAPER. 185 



butterflies were probably found in company with their pabula 

 throughout the whole of the northern portions of the Europasian 

 area, their range extending to well within the Arctic Circle. 

 Upon the advance of the ice-cap they retreated south until they 

 reached the six great chains of mountains which I have already 

 described. Many of the species were probably unable to sur- 

 mount the barriers which they furnished, and consequently 

 perished, whilst the majority perhaps forced their way through 

 them by means of transverse passes and valleys, and survived in 

 the sheltered and more hospitable areas which they would pro- 

 vide immediately to the south." Now this is a very pretty 

 theory, but what about the geological and other facts assumed? 



It occurs to me to ask Mr. Bath whether he thinks that any 

 scientific entomologist believes that the genus Erebia, as such, 

 existed in preglacial times '? As I understand Mr. Bath's 

 references, it would appear that his references to preglacial 

 times are especially directed to those observations which geolo- 

 gists have published relating to the subtropical fauna and flora 

 which are Isnown to have existed in the extreme north in the 

 Miocene period, and he assumes, so far as I understand his 

 writing, that Erebia and the Erebia species lived in the North 

 Polar Region at that time. If so, I would suggest that Erebia 

 would be, under these conditions, a subtropical genus, and, being 

 " driven southwards by the ice-cap," would, if it found subtropical 

 quarters south of the six great mountain chains, by the species 

 " finding their way through passes," to suit it, prefer remaining 

 in such quarters to attempting a return which led it out of sub- 

 tropical quarters, in order, apparently, to see how far it could get 

 up mountains, or how far it could get back to polar conditions 

 from, the '* remainder of Europe south of the mountain chains,"- 

 which during the glacial period were " capable of affording a safe 

 refuge to the alpine butterflies" during the dreadful time Mr. Bath 

 says they experienced at the time of the glacial epoch. 



One is constrained to ask, too, whether it would not have 

 been more to the point if Mr. Bath had given us, on the authority 

 of some capable geologist, the condition of the great mountain 

 chains that extend from the Pyrenees to Kamtschatka during the 

 periods comprised in, and that directly antecedent to, the glacial 

 epoch ; so that we might obtain some idea of the condition of 

 the mountains the butterflies are said to have crossed ? Sir 

 John Lubbock tells us that in the European part of the range as 

 much solid matter has been removed by denudation as now 

 remains. Geikie tells us that at the time of the glacial epoch 

 the whole of North Germany and the part of Europe in that 

 latitude was covered with glacial loess. It is well known that 

 the ice-flow from the Northern Alps set along Central Europe to 

 the east, and one would like to know where those places were to 

 be found "which we might fairly assume with a certain degree 



