MIMICRY IN CEYLON BUTTERFLIES. 15 
the so-called mimics, which were flying when I was at Trincomalee, 
were jungle lovers and generally avoided open spaces, e.g., Papilio 
polytes, Hypolimnas bolina, Pareronia ceylonica, &c., 1 cannot think 
it probable that, even if Asilids were discriminating in their attacks 
upon these butterflies, they would be afforded much opportunity 
of exercising that discrimination. 
In these three forms, viz., birds, lizards, and Asilids, I am inclined 
to think that we have the most serious enemies of butterflies in 
Ceylon. But my friend Professor E. A. Minchin, from observations 
that he made in Africa, has suggested to me that monkeys may 
also be a factor in the establishing of mimetic likeness. As to the 
possibility of this I can say nothing, for [had no opportunities of 
making any observations myself, neither do I know of any records 
which bear upon the point. In the case of P. polytes, however, I 
feel doubts as to their exerting much influence, for in the northern 
part of the Island, where these animals occur in plenty, the male form 
of P. polytes female is the most abundant, whereas the ‘‘ mimetic ” 
forms are more common higher up, where monkeys are very much 
searcer. But I would call attention to the suggestion here, in case 
others may have better opportunities of making observations. 
Formation of Polymorphic Forms. 
Those who regard natural selection as an adequate explanation 
of the formation of polymorphic forms hold that they have gradually 
arisen by the accumulation of small variations over a long series 
of generations ; and from this standpoint we may consider how the 
different female forms of P. polytes may conceivably have arisen. 
And in doing so, we shall assume that the form of the male is the 
ancestral one, and that the hector and the aristolochize forms have 
arisen from this. In other words, we shall assume that at some 
former epoch the species polytes existed only in what we now term 
the male form. And for our present purpose we may confine our 
attention to the evolution of the aristolochize form. Now, on the 
hypothesis we are considering, this may have come about in either 
one of two ways, according as we admit that P. aristolochie at that 
time existed as the form we now know, or was different. If 
P. aristolochiew was then as it is to-day, we must suppose that the 
aristolochiz form of polytes @ arose by gradual limitation of the 
white area on the hind wing, by gradual extension of the red lunules, 
and by gradual thinning of the scales between the nervures of the 
fore wing. The great stumbling-block to this view is the difficulty 
of attributing any selection value to the initial stages of variation. 
On the alternative view we may suppose the P. aristolochie bore 
a strong resemblance to P. polytes to start with, and that it gradually 
evolved into its present state because it was of advantage to it that 
the nauseous properties with which it was originally endowed should 
be advertised as conspicuously as possible. Meanwhile a parallel 
