270 



THE ENTOMOLOGIST S nECOllD. 



the rival claims of the generic names TricJioptcrij.r and Lobophora, 

 Tej)/irocli/stia and KtipitJwcia, Euccstia and Chesias, and many others 

 must remain sub jiidice : no fixed guiding principle in the matter is 

 discoverable in the action of Staudinger and Rebel. 



(To he contiuued.) 



Notes on the distribution of the British Coleoptera. 



By W. E. SHAEP. 

 (Coutiuiu'd fro)n p. 205.) 



We have now to consider the second of the groups nito which we 

 have, as regards their distribution, divided the British coleoptera. 

 This comprises the majority of such of our species whose range is 

 limited — its maximum density is in the south-east, whence it gradually 

 thins out westward and northward, until most of its members become 

 exceeding rare in Scotland and Ireland, and many completely absent. 



This group has been called the Siberian element in our fauna, on 

 the assumption that the original area of their specific development was 

 Siberia, whether this is so or not, it is sufficient for our purpose that 

 their proximate origin was the plain of central Europe, and that, at 

 the time of their arrival here. Great Britain must have been a north- 

 westerly extension of the continental area. That this was subsequent to 

 the maximum severity of the glacial epoch appears probable, for if the 

 group had existed since Tertiary times here, and survived the glacial 

 period, it is a fair assumption that its distribution would have been, 

 although perhaps very discontinuous, still more uniform from east to 

 west than we now find it. The main characteristic of the group, 

 however, is that as we proceed westward species disappear, not 

 sporadically but finally. There is also evidence that the land 

 connection between England and Ireland, which the limited com- 

 munity we find among species of the Celtic groujD proves to have been 

 intact during glacial and immediately post-glacial times, was most 

 probably interrupted during the advent of our second group. For 

 several of its members, although they arrived at what is now the 

 western seaboard of England, do not seem to have got to Ireland at 

 all. It is certainly quite true that up to within recent years very little 

 was known of the Irish coleopterous fauna, and that even now it 

 would be absurd to consider it as at all exhaustively recorded. Still 

 as the Irish deficiency in mammals, and still more in reptiles is certain 

 and notorious, we may be perhaps justified in supposing that the 

 species of coleoptera so far unrecorded there, are really wanting ; and 

 that what hindered their westward march was the fact that Ireland 

 became an island before all of them had completed it. 



In this respect the fauna of the Isle of Man becomes significant, 

 and it is the more unfortunate that so very little is know'n about it. 

 What evidence we do possess shows that its character is more Irish 

 than English, and includes even such a peculiarly Irish form as Silpha 

 sabrotundata. The deduction follows that when Mona was united 

 with Ireland (and the levels of the Irish sea bottom show that at such 

 an era land union Avith Scotland and England must also and to a 

 greater extent have existed), the Irish or Celtic group must have been 

 dominant, also that before its insularity became perfect, many species 

 of the eastward migration must have reached its confines. What 



