PLEBEIUS ARGUS VAR. CRETACEUS, N. VAR. 59 



darker, wider-margined (J ), heath form; (2) The larger, brighter, 

 narrow-margined ((?), chalk-down form; (3) The peculiar bright- 

 tinted, blue-suffused female, moorland form. We distinguished the 

 tAVO first-named in our British Biitterfiies, 1906, and the second of 

 these has since been referred to the Spanish race lujpochiona, Ramb., 

 but we think quite erroneously. We have a form just like it from 

 Scandinavia, and think it might even be fairly argued that it was the 

 form described by Linne, but for the present, and to prevent our- 

 selves being accidentally forestalled, we name it var. cretacens. 



The third form above, the moorland form, was largely on our 

 authority referred [Knt. llec, vii., p. 128) to the var. Corsica, Bellier. 

 This conclusion was based on a J and 5 received from Mr. W. E. 

 Nicholson of Lewes, as var. corsica, the two forms agreeing fairly well 

 on the upperside, especially in the ? , but it is, we have since dis- 

 covered, on the underside that Bellier de la Chavignerie found the 

 chief character of the Corsican form, and, in this, our " moorland " 

 form disagrees entirely. This form, like our " down " form, there- 

 fore, appears to require a distinctive cognomen, and we shall deal with 

 it in our revision of the species as var. massci/i, as we are indebted 

 entirely to Mr. Massey for our examples of the species, from which 

 our studies have been made, and we owe him some apologies for mis- 

 leading him, in our ignorance, into applying the name Corsica, to our 

 insect, on the first introduction of the race to the notice of British 

 lepidopterists. 



One other detail may be noted. Throughout Europe and Asia, one 

 of the most marked superficial differences between Plebeius argus 

 {aeiiou) and P. arfiyronnouion (art/iis) is found on the greater width of 

 the marginal border of the upperside of all four wings in the 3 . It 

 was not, we believe, until two years ago, when Mr. Powell visited Corsica, 

 and collected there for some time, that it became generally known that 

 Plebeius ar(i;/ro{/noi)wn was also to be found there. At any rate, it was 

 not till then that specimens of the latter species came into our posses- 

 sion. The insects were most puzzling, for, quite characteristic of P. 

 argyrocpioHion on the underside, and differing on this side most markedly 

 from P.argKsxav. corsica, the upperside of the P. anii/roiinoiiion 3 pre- 

 sents a wide marginal border that strongly suggests that of normal P. 

 cmjus {aeiion), whilst the J s of the latter from Corsica, almost with- 

 out marginal border, suggest normal P. ar<iiiro<jnomon. An examina- 

 tion of the very different 3 genitalia, by Dr. Chapman, proved that 

 the underside indication was correct, and that we had not only a very 

 special race, var. corsica, Bellier, of P. an/us, but an equall}^ peculiar 

 race var. corsica, n. var., of P. avtiyrofpiomoii. 



We hope to have the difficulties of the variation of P. argus fully 

 cleared up in the next two or three numbers of ouvXat. Hist, of British 

 pjiitterfiies, in which the original descriptions of all the forms will be 

 published for students' own reference, but the facts of this advance 

 note appear to be of sufficient general interest to all British 

 lepidopterists, to lead us to publish it. 



