INTERMEDIATES IN ABSENCE OF MODELS 273 



dential address to the Linnean Society in 1916. Dr. 

 Lamborn bred Papilio dardanus on the west coast of 

 Africa (South Nigeria), where the black and white form 

 hippocoon is almost the only form known. This mimics 

 the abundant Amauris niavius. Another form of dardanus 

 female has been caught rarely all along the tropical west 

 coast of Africa. This has a fore wing pattern approaching 

 that of hippocoon, but with the bar between the subapical 

 and inner marginal white areas very ill defined, and the 

 hind wings are yellow instead of white. This rare form 

 is known as dionysus, and there is no model for it in 

 Nigeria. 



Lamborn bred from a hippocoon parent nine female 

 forms like it, but also eight dionysus which has never 

 been bred before. Now these dionysus are in a position 

 similar to the Pseudacraeas which, in the absence of control 

 by the models on the islands, are producing large numbers 

 of transitional varieties, for no two of them are alike, 

 and they present a beautifully graded series, from a fore 

 wing pattern approaching that of hippocoon to a pattern 

 closely approaching that of the male. The nine hippocoon 

 sisters, however, mimicking the abundant Amauris, present 

 a very close resemblance to each other and to the hippocoon 

 parent. 



It is noteworthy that in the case of both Papilio dardanus 

 and Pseudacraea eurytus the variation in the absence 

 of models is best shown in the shape, size, and sharpness 

 of outline of a dark bar separating the paler portions 

 of the fore wing into two main areas. 



We now come to discuss another point of great interest. 

 If the collections of Pseudacraea eurytus from different 

 islands in the lake, sometimes very close together, be 

 compared, further evidence in favour of the maintenance 

 of mimetic resemblance by Natural Selection is obtained. 



Although the islets of Kimmi and Ngamba are so 

 very close to each other and Kome (see map), yet the 



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