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THE ENTOMOLOGIST. 



of safety might be found to the north of the Alps, the Pyrenees, 

 and the Carpathians," and " where a few species even survived." 



Let us summarize the well-known facts : — (1) ice to the north 

 of Germany ; (2) mountains existing where the Alps are now ; 

 (3) glaciers flowing north into France, Germany, &c. And then 

 we are asked to assume certain spots between the Alps and Baltic 

 Sea where butterflies might survive, whilst those that did not 

 survive pushed through transverse passes across the Alps — and 

 such Alps and such passes ! Then, as I understand it, there was 

 a journey back after it was all over. This is picturesque, but— 

 is it possible ? For some years I have been almost as much 

 interested in geology as entomology, but Mr. Bath's geology is 

 beyond me. 



Mr. Bath does not think "that the climatal conditions were 

 so severe as supposed by Hoffmann." This is a matter for the 

 geologists, and if they say it was — well, to say the least — as 

 specialists, I should take their opinion before that of Mr. Bath. 

 On the premises pointed out, Mr. Bath concludes that " the 

 great majority of the alpine forms of butterflies found a sanctuary 

 during the climax of the glacial period to the immediate south of 

 the three great chains of mountains on either continent." 



There is another phrase which I cannot understand. Mr. 

 Bath says he thinks Hoffmann " is incorrect in imagining that 

 the post-glacial alpine forms were not directly derived from the 

 south." Now Mr. Bath has been at great pains to show in his 

 paper that Hoffmann is wrong in supposing that the insects 

 during the glacial epoch did not go into the warmer parts of 

 Africa and Asia. This remark therefore means that Mr. Bath 

 believes tbat this fauna was directly derived from the south, and 

 "the south" as understood by Mr. Bath can only mean the 

 country between the Pyrenees, Alps, &c., and the Mediterranean, 

 so far as Europe is concerned, for he rules Africa out, not 

 believing that even " a few went into Africa" and returned when 

 the climate became warmer. 



If our authorities on the geological conditions of Europe 

 during the glacial epoch are correct, we have to deal with the 

 following facts : — (1) Ice as far south as the Baltic Sea, giving off 

 streams that flowed eastwards through Central Europe, and 

 deposited the famous loess deposits of Germany. (2) Glaciers 

 on the north face of the Alps, discharging also into the plains of 

 Central Europe, the water-flow being east. As the whole of this 

 central area was flooded during the Miocene period, one finds 

 some difficulty in believing that any Lepidoptera existed north 

 of the Alps, and hence it follows that Hoffmann's suggestion is 

 probably the correct one. The distribution of the Lepidoptera 

 previous to the glacial epoch is the merest guesswork. 



That any of our present species of butterflies existed before 

 the glacial epoch is very problematical — that the genus Erebia 



