(lee) 
the most obvious means of discrimination. May not this be 
the meaning of the fact that the males of the Hupleini may 
be divided into groups (which have been given generic names) 
distinguished, and sometimes solely distinguished, by remark- 
able differences in the size, number, form and position of the 
areas presumed to be scent-producing? These Hupleas are 
remarkable for the number of their synaposematic associations 
and for the closeness of the resemblance between the con- 
stituent species. So far as my experience goes,—and further 
inquiry in the same direction will tend to supply confirmation 
or refutation of the hypothesis here put forward—these 
associations are made up of species belonging to groups with 
different forms of sexual brands and not by species with males 
bearing the same type of brand. And now Mr. Kaye has 
shown that the close synaposematic pairs within the Heliconine 
sub-family are made up of species of which one belongs to the 
xlii] 
group with a broad the other to the group with a narrow 
band of glistening scales, in the male,—bands which are pre- 
sumably scent-producing. It is probable that the excessively 
close resemblance between these pairs and between the 
members of the Euplceine associations has been rendered 
possible without injury to the species by the existence of this 
means of instant recognition, and I think it is possible to infer 
the past history with a fair degree of probability. In the 
African Danaine genus Amauris we find two very common 
species as closely alike as any of the Eupleine or Heliconine 
Miillerian groups or pairs. I refer to Amauris echeria and A, 
albimaculata. It was at first thought that white spots in 
place of buff in the fore-wing alone distinguished these forms, 
and the general opinion followed that one was a variety of the 
other. But Rothschild and Jordan have shown that they are 
certainly separated by minute but well-defined and constant 
differences. Accompanying these, the scent-patches at the 
anal angle of the hind-wing of the male of albimaculata are 
about twice as long as those of echeria. It is probable that 
this wide difference has been a powerful aid in rendering 
possible the extraordinarily close resemblance. Already both 
species of this pair have undergone subspecific changes in 
