94 LEPIDOPTERA. 



softer tone, paler and more tinged with fulvous, the markings 

 more tawny, and those of the underside often tinged with 

 ochreous or orange-yellow ; the central stripe is more 

 angulated, and in it the discal lunule is almost always 

 absent. 



The principal phases of variation have already been men- 

 tioned in reference to the sexes and the two usual genera- 

 tions, but in both there is much irregularity in the distinctness 

 of the transverse lines and in the shades of colouring, some 

 of the earlier specimens being very much more coarsely dusted 

 with dark atoms, and having the central shade dark and 

 spread almost to the tirst line ; while others are quite brightly 

 tinted with chocolate-red, and in the second brood shade 

 to soft pale tones of reddish-white with only the faintest 

 expression of markings. Some of those from the North- 

 East of Scotland are richly shaded with rust-red. In London, 

 Mr. G. B. Eoutledge found that some pupa3 which should have 

 produced specimens of the second generation laid over till 

 February, and did not produce the ordinary spring form, but 

 had the colour of that of the summer, and the first line and 

 central stripe both twisted into segments of circles. In an 

 experiment on retardation by means of ice, Mr. Merrifield 

 obtained moths in which the central stripe or shade of the 

 first brood was visible, and also the more angulated one of 

 the second brood, so that these stripes crossed each other 

 twice in the middle of the wing. 



On the wing in April and the beginning of May, and as 

 a second generation in July and August ; occasionally in 

 confinement a third generation — resembling the second — is 

 obtained in September or October; and in the course of his 

 experiments Mr. Merrifield, by ihe free use of warmth indoors, 

 obtained yirc generations in one year, the race then becoming 

 exhausted and dying out. 



Larva twig-like ; third and fourth segments enlarged 

 laterally, eighth and ninth swollen, each with two small 



