HO THE BUTTERFLIES OF THE BRITISH ISLES. 



remarkable example of this kind of aberration, taken on the 

 cliffs between Dover and Walmer some years ago, is described 

 as of a clear milky-white colour, and has not, either on the upper 

 or under side of the wings, the smallest speck of black. The 

 ground colour is sometimes decidedly yellow, and very occa- 

 sionally brownish. 



The life-history of this butterfly is figured on Plate 74. 



The egg is whitish, opaque, with a dark speck on the apex ; base 

 flattened and slightly hollowed ; finely reticulated, but without 

 distinct striations or anything resembling ribs. The eggs are 

 laid in July, and are not attached to anything. 



The caterpillar when full grown, is whity-brown in colour 

 with brownish lines. The head is brown, tinged with pink, and 

 the tail-like points on the last ring are pink. The head, as 

 well as the body, is clothed with short hair. 



The chrysalis is also whity-brown with a pinkish tinge, 

 browner speckling on the wing cases, and the body is marked 

 down the back with yellow. 



Hellins says, u It hibernates when very small, becomes full 

 fed in June, and changes to a pupa without suspending itself 

 in any way, or making a cocoon ; I think it would hide itself, 

 as my examples did ; I found they had got among the thick 

 moss with which I had furnished the bottom of their cage, and 

 apparently made little hollows for themselves by turning round."' 



Cock's-foot grass (Dactylis glomerata) and cat's-tail grass 

 (Phleum ftratense) are given as food-plants, but the cater- 

 pillars in confinement seem to eat any kind of grass that is 

 supplied. 



The butterfly is found in most of the Midland counties and 

 in nearly all of the Southern ones, but is especially common 

 on the chalk downs of the South-west. It does not occur in 

 Ireland or Scotland, and seems to be absent from the Northern 

 counties of England except Yorkshire. In the last-named 

 county it was supposed to be extinct, but during the past ten 



