MAYER : COLOR AND COLOR-PATTERNS. 
271 
As the scales have been developed not because they aided the 
insects in flight or strengthened the wings, their retention must 
liave been due to some other cause, probably to their display¬ 
ing colors which were advantageous to their possessors in various 
ways. As Dimmock (’88) says, “ it is only in insects where certain 
kinds of brilliant coloration liave been developed that one finds 
scales.” Indeed, I believe that the vast majority of the scales 
found in Lepidoptera are merely color-bearing organs. They prob¬ 
ably first made their appearance upon small areas of the wings, 
perhaps adjacent to the body, and were merely colored hairs, sim¬ 
ilar to those of the surface of the body, which had grown out upon 
the wings. In this position they displayed some color which was 
of advantage to the insect; perhaps serving to render it less con¬ 
spicuous than formerly. Under these circumstances they would 
naturally be preserved through the operation of selection until 
finally they became modified into true scales ; just as the hairs in 
the Coleoptera have undergone a similar modification. If this 
be true, it is easy to see how they might spread out over 
the surfaces of the wings until the whole wing became covered 
with scales. 
(2) Summary of Conclusions. The scales do not aid the insects 
in flight, for the wings have precisely the same efficiency as organs 
of flight when the scales are removed. The phylogenetic appearance 
and development of the scales upon the scaleless ancestors of the 
Lepidoptera did not in the least alter the efficiency of their wings as 
organs of flight. This efficiency of their wing surfaces was probably, 
therefore, already an optimum before the scales appeared. The 
scales do not appreciably strengthen the wing-membranes, that 
_ • 
function being performed by the nervures. The majority of the 
scales are merely color-bearing organs, which have been developed 
under the influence of Natural Selection. 
PART B. 
COLOR-VARIATIONS IN THE IIELICONIDAE. 
I. General Causes which determine Coloration in the 
Hei jICONIDAE. 
In 1861, after eleven years of study within the forests of South 
America, Bates read his, now classic, paper upon the life and habits 
