© Ixxxx”_—) 
complete and wide. There can be no doubt that in this 
specimen we have a marked case of reversion to the original 
colouring of the female, but it is unaccompanied by any 
inchnation towards the recovery of the lost tail of the hind- 
wings. 
Returning to the general aspects of the subject, it is of 
importance to consider more closely how the evidence stands 
in relation to (A) persecution by insectivorous foes, (B) posses- 
sion of malodorous and distasteful juices by certain groups, 
(c) rejection or avoidance by foes of the insects provided with 
offensive juices, and (p) loss occasioned to distasteful species 
by the attacks of young and inexperienced enemies ; for it is 
admittedly on the co-operation of these factors that the theory 
of mimicry depends, 
(a,) As regards the first point, the broad fact of insects 
generally constituting the food of countless devourers, verte- 
brate and invertebrate, is beyond dispute; immense and 
incessant persecution is universally at work. But when we 
proceed to examine this world-wide persecution more in 
detail, and to ask in what special directions it works, or what 
groups or species are the particular prey of certain groups or 
species of enemies, we very soon discover how little is exactly 
known. Birds, for instance, are such notorious and appa- 
rently indiscruninate insect-eaters, and some of them are so 
active and demonstrative in their hunting, that it seems but 
reasonable to regard them as the chief pursuers on the wing 
of the abundant and defenceless butterflies. Yet in the 
discussion which followed the reading of Dr, Dixey’s last 
paper above referred to nothing was more noticeable than the 
very scanty testimony to such persecution on the part of 
birds that could be brought forward by the very competent 
well-travelled entomologists present. In fact, the poverty of 
observed cases of such attack has induced the opinion among 
some entomologists that birds very rarely chase butterflies at 
all, and the published expression of this view by Pryer, 
Skertchley, Piepers, and other experienced collectors cannot 
be overlooked. But I am persuaded that in this instance, as 
in so many others where the life-history of animals is con- 
cerned, the dearth of evidence is due to the neglect of well- 
