The first vary much in colour, being often nearly white with dusky yellow and red markings, but such differences often occur in butterflies.

The second group are much more extraordinary, and would never be supposed to be the same insect, since the hind wings are lengthened out into large spoon-shaped tails, no rudiment of which is ever to be perceived in the males or in the ordinary form of females.

These tailed females are never of the dark and blue-glossed tints which prevail in the male and often occur in the females of the same form, but are invariably ornamented with stripes and patches of white or buff, occupying the larger part of the surface of the hind wings.

This peculiarity of colouring led me to discover that this extraordinary female closely resembles (when flying) another butterfly of the same genus but of a different group (Papilio cooen), and that we have here a case of mimicry similar to those so well illustrated and explained by Mr.Bates.[ Trans.Linn.Soc.

vol.xviii.p.