THE PALE CLOUDED YELLOW 
329 
Aberration. Aberration consists chiefly in the development 
of the marginal bands. Occasionally the band on the fore 
wing is traversed down the middle by yellow, dividing it into 
two black bands. In an opposite extreme, the band is only 
faintly spotted, and in rare cases it is entirely black. The 
band on the hind wing is subject to great aberration ; in some 
specimens it is represented by only a few dark spots on the 
margin, while in others it forms a well-developed band spotted 
with yellow. 
In the Tring collection is a remarkable albinistic aberration, 
a male, having all the normal black markings replaced by 
pale amethyst, and all the markings on the under side are 
of a rich rose-pink ; the ground colour is a clear primrose- 
yellow. It was captured at Sheerness, Kent, on September 
1st, 1901. 
Occasionally specimens occur with longitudinal dusky 
streaks on the under side of the fore wings. 
As in other species of Pieridae, gynandromorphism is ex¬ 
tremely rare. 
Genus COLIAS, Fabricius, 1807 
THE CLOUDED YELLOW 
Colias croceus (Fourcroy, ijS^—cdusa). 
(Plate XXX, facing page 333) 
Haunts and Distribution. Like its near ally C. hyale, this 
richly-coloured butterfly is indigenous to the Mediterranean, 
region, whence in early spring it annually migrates over 
central and western Europe, and probably every year arrives 
on the British coasts in varying numbers during May or early 
June. As this species has no hibernating stage, a succession 
of broods occurs in its native home. 
This beautiful butterfly has a powerful and rapid flight, 
enabling it to take long migratory journeys. It occa¬ 
sionally arrives on our shores as early as April, but its usual 
time of arrival is in May or in the first part of June. Upon 
