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THE ENTOMOLOGIST S RECORD. 



abundance, and also from the fact that of all winged insects its 

 members perhaps use their wings the least, make it peculiarly suitable 

 for such an enquiry, and the problem we set ourselves is not of course 

 the phylogenetic origin of the coleoptera, for which, indeed, we should 

 have not only far to transcend the limits of these islands, but attempt 

 as hopeless an enterprise as any that biology can offer, for the 

 geological record, as regards insect evolution, is extensively frag- 

 mentary and discontinuous, and we have really not the slightest 

 evidence as to when, where, or how the differentiation of existing 

 specific forms among the coleoptera, or, indeed, among any order of 

 insects, took place. Our simple, but far from easy task, will be to 

 attempt to discover what light our knowledge of the present distribu- 

 tion of the British coleoptera can throw on their proximate derivation 

 and arrival here, and we need not go very deeply into the subject to 

 be made aware how small our knowledge of this really is, and how 

 very provisional all our theories on the subject must necessarily be. 

 And, firstly, we must recognise that no theory as to derivation drawn 

 from any one group of the fauna of any area can be considered even 

 plausible, unless it be supported or at any rate not refuted, by evidence 

 adduced from any other group either of fauna or flora in the same 

 area. Whether any of the conclusions to which we may be led from 

 a survey of our coleoptera are borne out by similar j)henomena in the 

 distribution of the flora or other groups of fauna is for students of 

 such groups to say, but I am at any rate not aware that they are likely 

 to be in violent opposition to them. 



I have stated already that our British coleoptera exhibit hardly 

 any specific distinction from those of north-western Europe, although 

 I am quite aware that over sixty have been enumerated as endemic to 

 these islands, but I think, on examination, this claim can hardly be 

 substantiated, as most of them are merely varietal forms and, for the 

 rest, no sufficient evidence exists that they are actually absent from 

 the continent, many of them having occurred as unique specimens only 

 in Britain. Since, therefore, our British coleopterous fauna is 

 practically European, it follows that, at no very remote date, Britain 

 must have formed part of some continental extension to the north- 

 west. That such a connection existed we have abundance of evidence 

 to show, but a very little study of this part of the subject will convince 

 the enquirer that the greatest importance attaches to the view Ave may 

 be disposed to take of that great climatic disturbance known as the 

 glacial age. That is to say whether, at the close of the tertiary period, a 

 change in climatic conditions occurred sufficient to extirpate all 

 previously existing forms of animal life throughout these islands, so 

 that, at the amelioration of so rigorous a condition of things, a 

 perfectly clear field was left for immigration from the south, or 

 whether glacial severity has been overestimated, the extermination of 

 pleiocene life a myth or exaggeration, and the possibility admitted 

 that our present fauna is merely a continuation, perhaps slightly 

 interrupted, of the late tertiary one. 



The first of these theories was that generally held until almost 

 quite recently, and we find such authorities as Professor I. Geikie, 

 Dr. Wallace and other eminent geologists committed to the " Green- 

 land " view of British glacial age conditions and to the virtual 

 extinction of all pre-existing life. If to this climatic severity we add 



