36 



AFRICAN MIMETIC BUTTERFLIES 



at Toronto in 1897, and in that year Marshall captured in South Africa several groups of 

 butterflies which included these insects, together with H. misippus and other mimetic forms. 

 The variety daira shown at Fig. 2 is distinguished by having lost the black and white markings 

 of the apices of the fore-wings, thus producing an exact parallel with the inaria variety 

 of H. misippus in mimicry of D. chrysippus dorippus, whilst in the white hind-winged form 

 alcippina, the variety corresponds to misippus alcippoides and chrysippus alcippus. In view 

 of the highly distasteful properties of the genus Acraea in general, the inclusion of A. encedon 

 in the chrysippus association must be explained on the Miillerian hypothesis. The fact 

 that it has been able to depart from the usual Acraeine facies and adopt the aposematic 

 pattern of another species is probably accounted for by the innate variability which, though 

 a common quality of the members of its genus, is perhaps more than ordinarily developed 

 in this species. Intermediate varieties are met with, but Professor Aurivillius gives the 

 following list of forms which have been specially differentiated : — 



1. encedon. The type as shown at Fig. i. 



2. infuscata, Stand. Similar to encedon, but the brown areas of a darker ' smoky ' 



appearance. 



3. alcippina, Auriv. The white hind-winged form, Plate III, Fig. 3. 



4. sganzini, Boisd. The typical Madagascar form, though also occurring in South 



and East Africa. The brown areas are replaced by yellow. 



5. lycia, Fabr. An albino form in which the brown areas are replaced by white. 



6. necoda. Hew. The Abyssinian form in which the brown colour is replaced by grey, 



and the apical black of the fore-wings is wanting. 



7. daira, Godm. and Salv. The form shown on Plate III, Fig. 2. 



An examination of these forms shows that infuscata is merely a melanic form of the 

 type and lycia an albino form. The necoda of Hewitson, judging from his figure, is an 

 intermediate between lycia and infuscata. 



On Plate VIII, Fig. 16, is shown an interesting form of A. encedon, in which the ground- 

 colour is of a more golden tint than usual, whilst the sub-apical bar in the fore- wings is suffused 

 with scales of the same rich yellow. The variety is very unusual, and was taken at Nyangori 

 on the north-east shore of Lake Victoria Nyanza, in company with Planema tellus and 

 Acraea jodutta. Should more examples of this variety be received, it will be reasonable 

 to conclude that A. encedon is developing a form in mimetic relation with Planema tellus, 

 a dominant model which with its other known mimics is described later. 



In geographical distribution A. encedon and its varieties show a far more perfect 

 coincidence with the forms of the model than do the varieties of H. misippus. The daira 

 form is rare in South Africa, where dorippus is almost absent, and it becomes commoner as we 

 pass northwards, where dorippus is also more numerous. Whilst all forms occur on the west 

 coast, alcippina is more frequently met with there than elsewhere, and from some parts 

 of the west coast specially large examples of alcippina have been received. The form lycia 

 has been considered to be a development in the direction of Acraea esehria. Marshall 

 in writing to Professor Poulton in 1896 (Trans. Ent. Soc, 1902, p. 479), says, ' That this 

 latter is the case I am led to believe by the fact that in Mashonaland only the type form 

 occurs, and there esehria is also absent; whereas along the south-east coast, where the 

 latter is plentiful, lycia occurs, and when I met with it in Durban I was struck with its 

 resemblance on the wing to the whiter specimens of esehria, though this is not so apparent 

 in the cabinet.' 



In describing the scents noticed in connexion with certain African butterflies, Dr. Dixey 



