466 Mr. G. A. K. Marshall on 



80. Description and Discussion of Material bearing 

 ON Mimicry in South African Rhopalocera col- 

 lected BY Guy a. K. Marshall, and the Record 

 OF Observations isiade ]5y him. (E. B. P.) 



Tlie splendid material which is described and discussed 

 below has gradually accumulated as the result of Mr. 

 Marshall's kind and generous response to my desire for 

 specimens for the Hope Department illustrating the fact 

 that mimetic species and their models, and the members 

 of large convergent or synaposematic groups, not only in- 

 habit the same areas but Hy together at the same time. 

 The study of this material naturally led to conclusions and 

 suggestions which it is hoped possess a general interest in 

 relation to the doctrine of evolution and the important 

 part which mimicry plays in it, as one of the chief evidences 

 of the operation of natural selection. These more general 

 discussions are placed under separate headings immediately 

 after the groups whose study gave rise to them. 



The last sub-section is placed under Mr. Marshall's name, 

 being quoted in cxtenso from his letters. 



A. Bladc-imd-Whitc Amauris-lilcc GrouiJ. 



The central model for the group described below is 

 probably Amauris ochlca, but it was not captured on 

 March 27, 1897, when five convergent individuals were 

 taken at Malvern, near Durban, Natal. The group as 

 captured is as follows : — 



Planema aganice $. 



„ esebria $, var. witli white markings. 



Neptis agatlia $. 

 2 Kydcviera leuconoe. 



The male Planema aganice is but an imperfect member 

 of the group, the lighter markings being buff instead of 

 white, as in the female. We thus find that the latter sex 

 forms closer synaposematic resemblances than the male, 

 when the two sexes difiler. It is probable that this rela- 

 tionship between male and female will be found to be 

 generally true of MUllerian mimics in which the sexes 

 exhibit diftereut degrees of hkeness to the type of some 

 group characterized by Common Warning Colours. Fur- 

 thermore, the culmination is often reached in Mlillerian 



