The Bionomics of South African Insects. 479 



insectivorous vertebrates and invertebrates are so much 

 more plentiful, this coloration was not sufficiently striking 

 to guard it from the tasting experiments of these enemies, 

 and thus the white bar would be gradually developed. 

 The typical form would therefore supplant Idugii in all 

 places where there was greater need of more efficient 

 warning colouring, and the latter form would only survive 

 in tliosc tracts where only a limited number of insectivorous 

 enemies could exist. Such an explanation Avould further 

 throw some light on the additional development of white 

 in the hind-wing of alcvpims in the prolific West Coast belt, 

 where the increased number of vertebrate enemies re- 

 quiriug to learn by experience renders an additional con- 

 spicuousness advantageous. It seems to me that if such 

 an explanation could be maintained it would be more 

 consistent with our general views; but of course the 

 matter hinges on the conditions of life in desert tracts, 

 which is merely an assumption on my part." 



" Salishury, Sept. 21, 1900. — I was much interested in 

 youi' remarks on the subject of klugii, and I quite agree 

 that now that you have shown that my premise as to the 

 conditions of life in desert countries is erroneous my con- 

 tention falls to the ground. I should like to know how 

 the range of the inaria form of misijypus falls in with your 

 proposition, and also whether you find the variety of AcriBa 

 cncedon without the white bar to follow the same range as 

 Idugii. I have found this variety \claira'\ extremely rare 

 in S. Africa, but a correspondent wrote me from Beira the 

 other day that it was not uncommon there and promised 

 to send me specimens." 



" Estcourt, Natal; Oct. 15, 1896. — I had thought Aciwa 

 encedon might be mimetic, but it must be a case of con- 

 vergence — the type towards Limnas chrysipjnts and the 

 variety lycia towards esehria. That this latter is the case 

 I am led to believe by the fact that in Mashonaland only 

 the type-form occurs and there escbria 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." 



''Malvern, Natal; Feb. 21, 1897.— The case of H. 

 misipims is however more puzzling than the Euralias 

 which mimic Aviauris. The inaria form of the female is 



