298 Dr. Frederick A. Dixey on the 
p- 244) that the genus Delias (Thyca of Wallengren), 
which is probably nearly related to Huterpe and Pereute, 
possesses a disagreeable flavour, or some other special 
means of protection. If this is shared by its American 
relatives, the first of the above requirements would be 
satisfied, while the second (2) has been shown to be met, 
in the special instance of the red basal patches, by the 
occasional presence of somewhat similar spots or 
patches (whose origin is not now under discussion) in 
other species of both the Papilionine and Heliconine 
groups, which afford quite sufficient material for the 
assimilative process to work upon. Until, therefore, 
direct proof is forthcoming of the edible qualities of the 
Pierines in question, it will not be unreasonable to sup- 
pose that they have joined an “inedible association,” 
and to attribute this curious agreement in a detail of 
pattern between members of such diverse groups to the 
operation of what may perhaps be called “ reciprocal 
mimicry.”’* The Pierines have no doubt moved furthest 
from their original form, having in most respects clothed 
themselves in Papilionine and Heliconine colours, but 
the latter have themselves advanced some way to meet 
the Pierines, in adopting from them a more distinct 
and characteristic employment of the red basal patches.+ 
* This, it will be seen, is distinct from “convergence” in the 
usual sense, inasmuch as that term has hitherto been employed 
(as by Poulton, ‘ Colours of Animals,” 1890, p. 195) to signify the 
assimilation of one form to another, rather than the mutual 
approach by two forms toa mean between them. 
t+ Fritz Miller notes (“ Kosmos,” 1879, p. 100, and translation 
by Meldola, Proc. Ent. Soc. Lond., 1879, p. xxiv.) that “in the 
province of Santa Catharina, Huterpe tereas is common in the 
forest-paths almost throughout the entire year, while its model, 
Papilio nephalion, is, on the other hand, a rare butterfly.” This is 
so far in favour of the supposition that the resemblance is not due 
to mimicry by the Pierine, at least in the strict sense. 
There igs one more piece of evidence that seems to favour the 
conclusion arrived at above. So far as I am aware no explanation 
has yet been offered of the fact that it is the females and not the 
males of Papilio polymetus, P. zacynthus, etc., that are resembled 
by Huterpe tereas and E. critias ; whereas the males, which display 
brighter colours, afford at least as good if not better models for 
imitation. I would suggest that this is really due to “reciprocal 
mimicry.” The protection gained by the resemblance between the 
Pierines and Papilios is not all on the side of the Pierines, but 
mutual ; and the female Papilios have, as is usual, felt the need 
of it more urgently than the males. For this reason the female 
