434 Mr. W. J. Kaye on Millhrian Buttcrjiics. 



la 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, Mdinma crameri and Hdiconius 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- 

 /c?'a joins in with 50 ^ of its forms dark and Lycorea ceres 

 with 40 y^. 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 

 feedinof. 



