XV 
THE RELATION OF FACTS TO THEORIES 
319 
mimicry, displaying itself only in the females, and 
not in all of these. According to M. Piepers, it is 
to be explained on the ground that the polymorphic 
forms represent successive stages in the transition 
between one monomorphic species and another. He 
is of opinion that the Papilionidse of the Malay are, 
for the most part, descended from ancestors with 
large spatulate appendices to the hind wings, but 
that many have lost or are losing these. In the two 
series P. Memnon-Androgeos and P. Theseus-Pannnon , 
the species are undergoing this transition ; the males 
and some of the female forms display the new type 
of structure, while certain of the female forms display 
in part ancestral traits. The resemblance between 
these female forms respectively and the other two 
series of butterflies ( P . Coon-Douhledayi and P. Hector- 
Diphihis-Antiphus') is not so great in the field as in 
the study, and is merely due to the fact that these 
two series display a more primitive type of structure 
and coloration, one nearer to that displayed by the 
hypothetical ancestor of the Eastern Papilionidae. 
The whole question is considerably complicated 
by the great variability of all the Papiliones , which 
makes it practically impossible to distinguish be¬ 
tween species and varieties ; while, on the other hand, 
the nomenclature employed has a considerable bear¬ 
ing on the question of mimicry, at least when repre¬ 
sented in tabular form. The mimicking females of 
P. Menmon and P. Androgeos are exceedingly alike, 
so much so that they were formerly classed together 
as one species. The chief difference is that the 
Javan form has yellow spots, while the Indian form 
has reddish. In the species P. Coon and P. Double- 
