434 Mr. W. J. Kaye on Miillerian Butterflies, 
In viewing the group as a whole what is most striking 
is that there is much closer agreement on the under-side 
than on the upper-side, and it is quite clear that selection 
must take place while the insects are resting with their 
wings folded. It should be convincing to the greatest 
sceptic that say the red apical marks on the under-side 
could never run through such a series if selection were 
made on the wing as is affirmed by all those who implicitly 
believe in the protective environment theory. What 
comes out clearly from these investigations is that only 
two species, Melinxa crameri and Heliconius vetustus, show 
a large proportion of specimens with a heavy black under- 
side. The tendency at the present time is all in favour 
of a banded under-side. On the upper-side the black 
development is far more pronounced as Mechanitis panni- 
Jera joins in with 50 % of its forms dark and Lycorea ceres 
with 40 “/. Whatever however may be the real cause of 
these darkened hind-winged forms so characteristic of the 
Guiana region it is certain that the forces at work are now 
not so potent for their development as for the more barred 
forms. It however may be that the selection for the 
upper-side made upon the flying specimen is acting much 
more slowly than upon the sedentary individuals, and 
this at least seems plausible as it is beyond question 
that the members of this large group spend the greater 
part of their time at rest on flower-heads and become so 
engrossed, that they show no inclination to fly, a collector 
being able to catch individuals with his fingers as they sit 
feeding. 
