

DEKIVATION OF BRITISH COLEOPTERA. 165 



streams of migration and so on, can be deduced from a 

 study of purely pelagic life. 



Thrown back, then, on our terrestrial organisms, and 

 leaving out of account the flora which, in many ways, 

 affords better and more abundant evidence than does any 

 part of our fauna, we find the mammals and reptilia far too 

 small in specific numbers to be of much service in the 

 enquiry. There are certainly in the distribution of our fresh- 

 water fishes most valuable and significant facts ; but it is 

 to the invertebrates which far out-number all the other 

 organisms put together that we find our most abundant 

 material and safest guides ; and of the invertebrates, 

 certainly the insects have been most closely and generally 

 studied, and of them consequently the British distribution 

 is perhaps best known. 



The majority of insects however fly, and, of course, 

 the evidence afforded by creatures whose transport is so 

 easy may readily become misleading; but of all the insects 

 the Beetles use their wings least ; in fact, some of them 

 do not possess these organs in any effective degree. The 

 Coleoptera too, are exceedingly numerous, both specifically 

 and individually, some 3,300 species being recorded as 

 British, and they are perhaps more uniformly and generally 

 distributed than any other order of insects. 



I will therefore invite your attention to what is known, 

 and still more, to what is unknown, of the distribution of 

 the Coleoptera of these islands and their possible derivation, 

 premising only that any inferences we may draw from 

 such facts, unless equally applicable to the distribution of 

 all the other fauna and all the flora as well, are theoreti- 

 cally invalid. 



Now the first broad fact to bear in mind is that the 

 whole British Coleopterous Fauna, and, indeed, we might 

 say the whole British Fauna, is simply part and parcel of 



