1^16] 139 



(2). It was driven far to the East during the Glacial period, whence it 

 ailvanced during favourable Inter-glacial periods, only to be driven back as the 

 climate oscillated. 



(3). The bulk of the present habitats of European forms were reached 

 during the last Inter-glacial period. 



(4). There is a gap in the British range of the species we have studied 

 which indicates that the species had a double origin here, one contingent 

 reaching Britain from France, and the other from Scandinavia. 



(5). The Scandinavian forms were forced south-west by the last Baltic 

 glaciers, which had but little effect in Britain. 



(6). This explains how all our Northern forms are Northern and Western 

 in distribution, and do not appear to have advanced from the Sovith as the ice 

 retreated, as we are usually asked to believe. 



(7). This may explain the curious and anomalous mixture of Northern and 

 Southern forms, seen in some of the Pleistocene deposits of Western Europe. 



181, Abingdon Eoad, 



Middlesbrough : 



March, 1916. 



Bornean Rhojaalocera : a reply to a criticism hy Mr. H. H. Druce. — The 

 February number of the Ent. Mo. Mag., in which Mr. Druce has criticised 

 my paper on Bornean Rliopalocera, has jiist been forwarded to me from 

 Sarawak. Although my regiment is stationed at present in the Himalayas, and 

 I am thei'efore out of reach of any entomological literature, I wish to lose no 

 time in attempting to remove any false impressions which his remarks may 

 have created. 



Mr. Druce's chief complaint is that I have made no mention, either in my 

 short preface or in my bibliography, of a paper by Mi-. Herbert Druce on a 

 collection of Bornean butterflies, and of two papers by himself on Bornean 

 Lycaenidae. The explanation is simple : the bibliography, which Mr. Druce 

 takes the trouble to stigmatise as " of coiirse, very incomplete," merely lists 

 eight papers, and I really thought it hardly necessary to state that those eight 

 papers made no pretence of being a complete bibliography for the huge subject 

 of Bornean Rhopalocera* Two of the first three papers are mentioned because 

 they appear in unexpected and little-known publicationsf ; the next three papers 



* In my " Hand-List of the Birds of Borneo " I gave an " extensive, but by no means complete" 

 (as I described it) bibliography, which listed 232 papers by liS different authors. Now the birds 

 of Borneo number 550, while the butterflies run to some SO ' different forms. A complrtr biblio- 

 grapliy for the latter, which have been collected and studied for more than 60 years, would contain 

 rather more than eight papers. 



t Mr. Druce advocates republishing these papers in some more accessible journal. The late 

 Mr. Shelford has already pointed out that they have no value as entomological literature, and that 

 their historical interest is hardly sufficient to warrant their conservation. Some nomina mala arc 

 introduced in one of them ; no original descriptions in either. The species enumerated are fully 

 discussed by Shelford and myself in the i-espective portions of our list of the butterflies of Borneo. 



M 2 



