S Dritte allgemeine Sitzung. 
brown head, legs, and part of the body are seen beneath the 
green burden!). It is manifestly absurd to attempt to account for 
this series of mimetic resemblances by an appeal to the operation 
of External or Internal Causes or of Sexual Selection. There 
remains Natural Selection which at once offers a convincing inter- 
pret tation. Ants and Wasps are known to be aggressive dominant 
insects avoided by the majority of insect-eating animals, although 
certain species are adapted to feed almost exclusiv ely upon them. 
It is in every way probable that a superficial resemblance to 
ants and wasps would be beneficial in the struggle for existence. 
There is indeed some experimental evidence to prove that real 
advantage is conferred’). We find that species of many seis 
mimic ants and wasps in a variety of entirely different ways. The 
results are exactly what might there been predicted to occur if 
Natural Selection be the efficient cause of mimetic resemblance. 
The attempt has been made, in recent years, to cut away the 
foundation of an interpret tation based on the theory of Natural 
Selection, by calling in question the conclusion that butterflies are, 
as a matter of fact, attacked by insect-eating animals such as birds. 
I have recently collected together a great mass evidence bearing 
on this point, most of it obtained in Mashonaland, South Africa, by 
the admirable naturalist Mr. Guy A. K. Marshall. This material con- 
clusively proves that the wings of fresh unworn specimens of butter- 
flies are constantly notched as if by the attacks of birds and lizards, 
and that in a considerable proportion of the examples the notches 
on opposite sides fit together, proving that the insect was seized 
when its wings were in contact. The attacks are most frequently 
directed to the posterior angle of the hind wing, less frequently 
to the tip of the fore wing, still less frequently to the intermediate 
borders and angles. The points of attack are those where special 
marks and structures, probably having a directive function, are 
frequently developed. Thus the tip of the fore wing is frequently 
rendered specially conspicuous and the posterior angle of the hind 
Wing is continually produced into so-called ,,tails* (Papilio, Cha- 
raxes etc.) which in the Lycaenidae are often antenna-like and 
associated with eye-spots, suggesting the appearance of a head, 
a resemblance further intensified by movements of the hind 
wings during the resting position which cause the apparent 
antennae to pass and repass each other. Such structures and marks 
are constantly injured or entirely bitten away in fresh specimens. 
Direct observation of actual attack by birds and lizards has also 
1) See description and figure of a specimen found by Mr. W. L. Sclater in 
British Guiana. Poulton, in Proc. Zool. Soc, 1891, p. 462. 
2) Poulton, ,,Colours of Animals“, London 1890, p. 247: Lloyd Morgan 
» Animal Behaviour‘, London 1900, p. 164, 165. 
