218 THE ENTOMOLOGIST. 



(in litt.) that the mere fact of its not having been turned up in. 

 these regions does not necessarily imply its non-existence there^ 

 Vast tracts of country in Western Norway remain to be explored 

 entomologically and in Sweden, but it is certainly remarkable 

 that we bave no notice of it in the careful and usually accurate 

 reports of those Scandinavian, l^'itish and German collectors- 

 who have visited tbe less northerly localities, such as, for 

 instance, the Dovrefjeld, where it might be expected. Assuming,, 

 however, that it did follow in the wake of the northern invasion 

 from the east — and it has been taken in Siberia — it is also surely 

 not a little remarkable that A. achillece should not have been 

 observed in the eastern watershed of Scotland, which, in contra- 

 distinction to the Continental countries enumerated, has been 

 terra cognita to naturalists for tbe past century. That A. exulans 

 should have escaped detection until as late as 1871, when it was 

 taken by Mr. Traill and Dr. Buchanan White, is hardly so sur- 

 prising, as subsequent exploration of the mainland has failed to 

 locate this species elsewhere than about Braemar. Mr. B. S. 

 Curwen, who exhibited a series at the South London Society in 

 1915 labelled " N. Shetlands," tells me be had them from Mr. 

 A. E. Cannon, and has no reason to doubt the accuracy of the 

 record. Achillcce also may be turned up in some interven- 

 ing localities between the east and westcoa&ts, for even assuming 

 Hubner's grouping of the two species in Lycastes to be warranted 

 by structure, it is hardly conceivable that achillea has been 

 evolved in this direction from the ancestral exulans of the Scottish 

 mountfiins. It is a more likely hypothesis that tbe achillcce of the 

 Atlantic slope — where, as Mr. Sheldon foresees, it is likely to be 

 found still further extended in the future — reia-esents the western 

 outposts of a species which once extended into and over what 

 is now part of the British Isles from east to west. The mystery 

 of its colonisation of tbe Western Highlands, then, derives no 

 elucidation from its recorded distribution in the north of Europe. 



A. achillece, as we know it to-day, is in fact more familiar, in 

 relation to our islands, as a central and south European species. 

 But, as it has not yet been detected in England or Wales, its 

 Scots origin can hardly be attributed at present to immigrants 

 from western France. Unfortunately I have no complete chain 

 of evidence, even for the butterflies, of the French maritime 

 Departments of the Channel. Such authorities as I have been 

 able to consult suggest in Western Europe some affinity for 

 achillece with the northward distribution of IpJiidides podalinis. 



Achillece is recorded actually on the coast by Viret, "rather 

 common on the cliffs of St. Valery-en-Caux," between Dieppe 

 and Fecamp, while at the south-west extreme of the same 

 Department it is reported from Orival in the Seine valley above 

 Eouen.* M. Paul Noel states that it is common in this Depart- 



* ' Lepids. du Dept. de la Seine-Inferieure,' G. Viret, Eouen, 1874. 



