ILLUSTRATIVE OF NATURAL SELECTION. 183 
The Papilios which resemble them belong to a very 
distinct section of the genus, in which the sexes differ 
greatly ; and it is those females only which differ most 
from the males, and which have already been alluded 
4o as exhibiting instances of dimorphism, which resem- 
ble species of the other group. 
The resemblance of P. Romulus to P. Hector is, 
in some specimens, very considerable, and has led to 
the two species being placed following each other in 
the British Museum Catalogues and by Mr. E. Double- 
day. I have shown, however, that P. Romulus is 
probably a dimorphic form of the female P. Pammon, 
and belongs to a distinct section of the genus. 
The next pair, Papilio Theseus, and P. Antiphus, 
have been united as one species both by De Haan 
and in the British Museum Catalogues. The ordi- 
nary variety of P. Theseus found in Java almost as 
nearly resembles P. Diphilus, inhabiting the same 
country. The most interesting case, however, is the 
extreme female form of P. Memnon (figured by Cramer 
under the name of P. Achates), which has acquired 
the general form and markings of P. Coon, an insect 
which differs from the ordinary male P. Memnon, 
as much as any two species which can be chosen | 
in this extensive and highly varied genus; and, as 
‘if to show that this resemblance is not accidental, 
but is the result of law, when in India we find a 
species closely allied to P. Coon, but with red instead 
of yellow spots (P. Doubledayi), the corresponding 
variety of P. Androgeus (P. Achates, Cramer, 182, 
