SATYRTD^. 243 



variation, in rare cases, an attempt at more symmetrical 

 arrangement of the white patches, as in a specimen in the 

 collection of the Eev. Joseph Greene, the hind margins of 

 all the wings of which are whitish, and the white colour is 

 continued inwards between the nervures (which are broadly 

 dark) in such a manner that both fore wings are variously, 

 and both hind wings broadly, rayed inwards with white, 

 which, however, fades into the usual dark colour about the 

 middle of the wings, except that there is a yellowish blotch 

 in the discal cell of each fore wing. This specimen is not 

 only remai'kable but exceedingly pretty. Another taken by 

 Mr. W. Holland near Reading is somewhat similar, but the 

 margins are dark, and the whitish dashes between the 

 nervures on all the wings are smaller and less distinct. In 

 these specimens the under-side is still whiter than the 

 upper, and there is no separation by dark nervures. To 

 some small extent this class of variation appears to be 

 local and recurrent — that is to say, that such specimens are 

 more frequent in restricted localities than elsewhere ; and 

 it has been the theme of much speculation, some observers 

 believing that the whiteness is caused by actual bleaching 

 of the dark scales by means of moisture, or of sunlight in- 

 tensified by passing through drops of dew, or of rain, 

 falling upon the soft and undeveloped wings immediately 

 after emergence from the pupa. Apparently no actual 

 evidence has been obtained, and this peculiar variation 

 doubtless arises from other, and at present unknown, causes 

 operating in one of the earlier stages. 



On the wing in June, July, and even August. Occasionally 

 in the latter month casual specimens will occur, perfectly 

 fresh, but considerably smaller than usual, and appearing to 

 belong to an extremely partial second brood ; but this occurs 

 only in exceptionally fine and warm summers. 



Larva, slug-like, rounded, tapering to each extremity ; 

 head larger than the second segment ; anal segment forked ; 



