178 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



To a consideration of this assemblage we will therefore 

 now proceed, and it undoubtedly exhibits perhaps the 

 most puzzling features of them all. I should include in 

 this group, firstly, all species whose northward range does 

 not pass beyond the Thames Valley and the Bristol 

 Channel, and secondly, a certain number of Southern 

 European forms found in Ireland, but not to the same 

 extent in England. There can be no doubt but that this 

 element in our fauna is distinctly southern, or relative to 

 Europe as a whole south-western. There seems to have 

 been two lines of migration, one, which crossing the 

 English Channel from directly south, does not appear to 

 have extended further westward than Devonshire, another 

 which seems to have had an origin in some much more 

 western ancient land extension, spread itself through 

 Ireland in a curiously disconnected manner, and left 

 vestiges of its migration in Cornwall and Devonshire. 



Calling this then the southern group, we find : — 



Firstly, species such as Lucanus Cervus, Cicindela ger- 

 manica, or Carabus intricatus among the Beetles. Among 

 other insects, the Giant Earwig, only known to inhabit a 

 few isolated spots along the Sussex and Hampshire coast, 

 or the butterfly called the Lulworth Skipper, found only at 

 Lulworth, in Dorset. These are species which do not 

 extend northward of the Thames Valley, are very rare or 

 absent west of Dorset, and quite absent from any part of 

 Ireland. 



Secondly, species common to the south and west of 

 Ireland and England, but principally the extreme west of 

 England ; such are Mesites Tarclyi and Chrysomela Banksii. 

 Some of these exhibit discontinuity of range to so high a 

 degree as almost to suggest two separate streams of migra- 

 tion. Thus Pyropteriis affinis, a brilliant scarlet Beetle and 

 one not likely to be overlooked by collectors, has so far been 



