i64 LEPIDOPTERA. 



Hind wings grcyish-wliite, faintly dusted toward the costa 

 with pale brown ; central spot dusky black ; beyond it is a 

 slender, indented, cloudy blackish transverse stripe, and before 

 the hind margin a broad pale grey band interrupted by white 

 nervures ; extreme margin white, edged with a black line ; 

 cilia white, legs pale brown, barred in front with darker 

 brown ; leg tufts and body yellowish or greyish-white. 



Variation in this species is very considerable — apparently 

 local or in some degree climatal — and consists mainly in 

 more or less suffusion of the ground colour with grey or 

 smoky-black. In the South of England the ground colour 

 is usually white, sometimes brilliantly so, occasionally with 

 brownish clouding along the costa, in other instances rendered 

 more extensively white by partial obliteration of the transverse 

 lines and shades, in which case the large stigmata become 

 conspicuous. Away from the extreme south a clouding of 

 darker, or a darkening of the markings, or both, very soon 

 become manifest \ even in Berkshire one wood will produce 

 white forms in abundance, and another, but a few miles 

 distant, equally plentiful greyer variations. This becomes 

 intensified in the Midland and Northern counties, while both 

 forms are mingled in the Eastern and Western, and the 

 extreme is reached in Cheshire, where in the Delamere 

 Forest region specimens are frequently obtained wholly 

 suffused with smooth smoky-black and hardly presenting a 

 trace of the usual markings, the stigmata being only indi- 

 cated by paler clouds ; while the hind wings are also smoky- 

 black, but with the cilia white. This singular melanic form 

 was discovered only a few years ago by Mr. J. Collins, of 

 Warringon, but has, I believe, been found every season since, 

 and now is taken also in South Yorkshire. In the inter- 

 mediate gradations of colour this obscuration of the markings 

 is rarely visible ; usually they are blacker than the grey or 

 smoky ground colour. In a specimen taken near King's 

 Lynn, Norfolk, the general dark colour and markings are 

 relieved by slender white stripes in the places of the usual 



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