LAKENT/D-li—C/DAK/A. 277 



white, without tlie usual faint brown lines, cand almost with- 

 out the submarginal clouding ; the black markings toward 

 the apex, however, are generally visible. Where this form is 

 approached, intermediates between it and the type are also to 

 be met with, especially near Dover, Kent, and in Sonth York- 

 shire, and the intermediate form also in the north of Ireland. 

 In anotlier local race, found principally in the north of 

 Yorkshire, Durham, Northumberland, and some parts of the 

 east of Scotland, the fore wings are (piite filled in with dark 

 umbreous or Ijlack-brown colouring, to the exclusion of all 

 the pale brown or brownish-white, though in some of these 

 the white line which edges the basal blotch is slenderly 

 visible, and the dotted white subterminal line even more so. 

 In these the hind wings are darkened toward the hind margin. 



With regard to the beautiful local variety, having the ground 

 colour clear creamy-white, or creamy lirownish-white, a very 

 curious circumstance has been observed by Mr. Sydney Weblj : 

 that the strain is not crrn, nor in the least progressive — that is 

 to say, that eggs of a very purely-coloured extreme specimen 

 of the variety do not produce the like, or an advance upon 

 it, but always revert toward the typical foi-m or to some 

 intermediate; the more full variety being again produced in 

 another generation from eggs of the internaediate. This, he 

 assures me, is the result of experiments extending over some 

 years. 



On the wing in April and ^lay, but casual specimens may 

 lie found in some seasons in June, or even July. Such 

 specimens have been noticed in Hevon, and attributed to a 

 second generation, as also have some very small exam])les 

 which I myself took in July or August, in Pembrokeshire ; 

 yet this is still open to doubt, and Jlr. S. Webb, from his 

 experience, is strongly of opinion that there is only one 

 emergence in the year, with perhnjis a casual specimen of a 

 second generation iii Si/i/i„ihi ,-. 



L.ARVA. Head rather small, ])ale brown, freckled with 



