374 I.EPIDOPTERA. 



wings })ale smoky-brown dusted witli darker ; central spot 

 black ; cilia s|X)tted with smoky-black. Body and legs 

 whitish-bniwu ; tarsi green, barred with black. 



Kxcessively variable, indeed the description above refers 

 only to the most abundant forms of the species in its more 

 general lowland tyjje. In all the description no colonr 

 and uo marking seems really stable. Some S[)ecinieus ap- 

 proach to a unil'iirm green colour, tlie stripes absent, or some 

 of them so, or their originating costal .spots alone remaining ; 

 others have the stripes before the middle massed together 

 into a broad band ; others those beyond the middle also ; 

 while still others have the entire wing covered with dark 

 stripes and clouding ; often the pale middle band as.serts 

 itself, sometimes entire, in other cases broken into two or 

 more well-defined, island-like spots. The snbmarginal round 

 white spot is usually visible, large or small, or obscured, but 

 not rarejy quite absent. And these mutations have no con- 

 nection with each other, but are mi.xed up in every possible 

 way. In addition to this tangled series of forms of the 

 general country and the woods, there is a definite race upon 

 hills and mountains, and on the moors of Scotland and the 

 North of England, liut especially' abundant on the hills of the 

 Western Isles of the former country. In this race the size is 

 reduced by one-third or even by one-half — certainly by one 

 half the area in most specimens — and the colour is totally 

 different, dark rusty-brown, dark greenish-brown, blackish- 

 brown, rusty-black, or olive-green ; the markings all obscure, 

 very often obliterated by the dark colouring ; when visible only 

 so by faint paler outlines or greenish mottling, but the white 

 submarginal spot often indicated and occasionally snowy white. 

 This strain of variation seems always, or nearly so, to frequent 

 whortleberry, the larva3 feeding thereon ; yet this food cannot 

 be the sole cause of difference, since larviu found in plenty 

 feeding u]ion this plant in Kent produced moths of the general 

 type, and only differing from others of the southern dis- 

 tricts in feeding up more quickly, and emerging earlier in the 



