SOME NOTES ON PLEBEIUS ARGUS. 75 



ful examples taken at Bofli<, in Norwegian Finmark, by Mr. W. E. 

 Nicholson on July 31st, 1896. Of my own captures, twelve are 

 females, and, with the exception of two from Alien,* all show 

 traces of blue on the four wings, and in most of them the blue 

 extends from the base to the discoidal cell, and in some to the 

 ante-marginal black band; in no single instance, male or female, 

 would it be possible for anyone who has observed cBgon and argus 

 in the field to confuse these examples of the arctic variety with 

 any known form of fegon. Mr. Nicholson's Bod0 examples are 

 even more unmistakably a form of argus, though the two 

 females are rich brown without the blue wash on the upper side. 

 One male is sky blue ; the other purplish blue (the characteristic 

 blue of the species) ; the under side ante-marginal orange border 

 is continued through from the apex of the fore wings to the inner 

 margin ; both on the hind wings and the fore wings it is of a far 

 deeper orange-red (rodgul) than in the smaller examples from 

 South Lapland and Alten. The females are equally brilliant on 

 the upper and under sides, the metallic spots in both sexes large 

 and bright, as in the case of Mr. Standen's female example from 

 Soon. 



These latter I have also compared with the various forms of 

 urgus from the North of Europe ui the Natural History Museum 

 Collection, and I can come to no other conclusion than that the 

 Plebeius '^ cegon var. Corsica'" of Mr. Standen is actually a local 

 form of P. argus transitional from lapponica, but so close to it as 

 hardly to require the conventional "trajisiius ad." ; the female is 

 therefore var, ccerulea, Strand ; the male in size and shape is not 

 unlike Gerhard's figure of var. agiades, to which I shall refer 

 later. 



As there still appears to be a doubt regarding the nomen- 

 clature of the Scandinavian forms of argus, I venture to offer a 

 few remarks on the subject. 



I gather from the bibliography preceding Tutt's comprehensive 

 study ('British Butterflies,' vol. iii, p. 165) of Plebeius cegon 

 {which he calls argus, L.) that he identifies the idas of Zetter- 

 stedt (' Insecta Lapponica,' p. 19, 1839) with a form of agoji. 

 This view, in my opinion, is untenable, for cegon, as I shall 

 presently show, nowhere penetrates the Arctic Circle ; and 

 Zetterstedt's description, " ccerulea- argentis pupillatis," disposes 

 of the identification with Meissner's cegidion, which Tutt, 

 no doubt rightly, identifies with Bergstrasser's philonomus, a 

 central alpine form of cegon in which the metallic spots are 

 wanting. Scandinavian lepidopterists of the present day 

 have accepted this conclusion. For example, Wahlgren (' Ent. 

 Tids.,' 1912, p 83) discussing the butterflies of Angermanland, 

 though he sticks to argyrognomon as the type-form name, cites 



* A similar range of variation is observable in the $ P. icarus taken at the 

 same time in this locality. 



