The ground tint of the wings is an exceedingly rich orange-yellow, or saffron colour, surrounded by a border of very dark brown, sometimes nearly black. This border is marked, in the male, with thin yellow _lines_, and in the female with _paler yellow spots_. There is a beautiful rose tint in the fringe of the wings and on their front edge. Underneath the wings are paler yellow, taking a citron hue in some parts, and marked with black and brown; in the centre of the under wings is a brown-circled silvery spot.
There is a peculiar and constant _variety of the female_, in which all the yellow portion of the upper surface is replaced by a _greenish white_ tint; but in every other respect the insect agrees with the common form of _Edusa_. This interesting variety was formerly ranked as another species, under the name of _C. Helice_; but it is a curious fact that no corresponding variety of the male has ever been observed; and last year I captured a pair together--a white female and common orange male--who were on those terms of tender intimacy which are generally supposed to betoken identity of species. { 75}
Varieties of the female are also met with, of various intermediate shades of colour between the white and the ordinary orange.
Yet is it not possible that all these varieties may be mules between _C. Edusa_ and _C. Hyale_ (the next species), the males of which are often seen pursuing the lady _Edusas_? but if so, as indeed it would be on any other hypothesis, it is hard to account for the unvarying character of the male.
This butterfly is also called the Clouded Saffron.
THE CLOUDED SULPHUR, OR PALE CLOUDED YELLOW BUTTERFLY. (_Colias Hyale._)
We may, in general, readily distinguish this elegant insect from the last species--the females of which it rather resembles in its markings--by the difference in the ground tint of the wings, which in this vary from primrose or sulphur yellow to a greenish white.
There is, however, some risk of confounding this with the white variety of _Edusa_ (_Helice_), a mistake often committed by young entomologists; so it will be well to point out the most prominent distinction between the two; and this is easily done, by observing that in _Edusa_ the dark border of the upper wings is of nearly { 76} equal breadth along the whole of the outer margin, and _at the lower corner is continued inwards for a short distance_; whilst in _Hyale_ this border _narrows rapidly, and disappears before reaching the lower corner of_ the wing. Also the dark border of the hind wings is much broader in _Edusa_ than in _Hyale_. Here we have distinctive marks, quite independent of the ground colour of the wings.