The Descent of Man

certain other tropical groups, and in some of
our English butterflies, as the purple emperor,
orange-tip, etc. (Apatura Iris and Anthocharis
cardamines), the sexes differ either greatly or
slightly in colour. No language suffices to describe
the splendour of the males of some tropical
species. Even within the same genus we
often find species presenting extraordinary
differences between the sexes, whilst others
have their sexes closely alike. Thus in the South
American genus Epicalia, Mr. Bates, to whom I
am indebted for most of the following facts,
and for looking over this whole discussion,
informs me that he knows twelve species, the
two sexes of which haunt the same stations
(and this is not always the case with butterflies),
and which, therefore, cannot have been
differently affected by external conditions. (5.
See also Mr. Bates's paper in 'Proc. Ent. Soc. of
Philadelphia,' 1865, p. 206. Also Mr. Wallace on
the same subject, in regard to Diadema, in
'Transactions, Entomological Society of Lon-