?>78 Professor E. B. Poulton [March 5, 



It is impossible to regard the resemblance of an Acraea like 

 A. alciope or A. althoffi for a Planema, also belonging to the 

 specially protected Acraeinse, as anything but examples of Slullerian 

 Mimicry, or Common Warning Colours ; and this conclusion is even 

 more obvious when the rarer species of FJanema assume the patterns 

 of other Planemas when they enter the areas where these predominate. 



The final illustrations, taken from the genus Charaxes, introduce 

 a novel aspect of butterfly mimicry ; for both models and mimics 

 are regarded by C F. M. Swynnerton, who has observed and experi- 

 mented with birds and their insect prey for many years, as among 

 the most palatable of insects. Yet there can be no doubt about the 

 fact that the large species of Char axes are mimicked by the smaller 

 ones, and that some of the larger species mimic each other. Mimicry 

 in the African Charaxes has been chiefly studied by Dr. Karl Jordan, 

 who has most kindly suggested many of the examples that have been 

 used as illustrations. These resemblances have also been observed in the 

 field by G. A. K. Marshall, C. F. M. Swynnerton, Rev. K. St. Aubyn 

 Roo-ers, and S. A. Xeave, who also recognized a particularly striking 

 'example in the collection made by C. A. Wiggins in the north-east 

 corner of the Victoria Xyanza. Nevertheless, in spite of this general 

 recognition, very little has been published or exhibited on the 

 subject. 



The senus Charaxes is confined to Africa and the adjacent 

 islands, it^ place being taken in the Oriental and Australian regions 

 by the closely allied genus Eidepis, in which, however, mimetic 

 resemblances have not been recognized. The butterflies are strongly 

 built and extremely powerful in flight, the thorax containing the 

 wing-muscles being specially capacious. They are strongly attracted 

 by fruit, exuding sap, and putrid substances, becoming after a time 

 almost entirely engrossed in their food, although up to this point 

 remarkably alert. C. F. M. Swynnerton informs me that before 

 alighting to feed they will fly backwards and forwards about the 

 spot, displaying the upper surface of the wings : and that when 

 they have alighted they will sometimes open their wings with a snap 

 when disturbed, although a more usual response is to move the hind 

 wings in such a manner as to display conspicuously the " tails " and 

 exhibit the " eye spot " which, in many species, is found on the 

 under surface oi the fore-wing where it is normally covered by the 

 hind, when the wings are held upright over the back in the attitude 

 of rest. The meaning of these movements, diverting attention from 

 the vital parts to the borders of the wings, is rendered clear by the 

 frequency with which injuries are found in these positions. 



When a Charaxes is seized its great strength enables it to struggle 

 violently, and the effect is almost certainly intensified, in the larger 

 species, 'by the serrated front edge, or costa, of the fore wing. In 

 addition to this " fighting weight," Swynnerton finds that their 

 chitinous exo-skeleton is so tough that an insectivorous bird will 



