The Descent of Man

in beauty; for the females alone have the borders
of their wings suffused with crimson and
orange, and spotted with black. The plainer
males of these species closely resemble each
other, shewing that here the females have been
modified; whereas in those cases, where the
males are the more ornate, it is these which
have been modified, the females remaining
closely alike.
In England we have some analogous cases,
though not so marked. The females alone of
two species of Thecla have a bright-purple or
orange patch on their fore-wings. In Hipparchia
the sexes do not differ much; but it is the
female of H. janira which has a conspicuous
light-brown patch on her wings; and the females
of some of the other species are brighter
coloured than their males. Again, the females of
Colias edusa and hyale have "orange or yellow
spots on the black marginal border, represented
in the males only by thin streaks"; and in Pieris