MIMETIC ASSOCIATIONS 



57 



East Rhodesia, and to Mount Kilimanjaro, but is rare in Cape Colony. The variety steckeri 

 is peculiar to Abyssinia, and has a very narrow band on the hind-wing, and numerous 

 marginal spots, and the fore- wing spots, hind- wing patch, and other pale markings are brownish- 

 ochreous. The variety jacksoni is generally larger, has a well-marked spot in the discoidal cell 

 in the fore-wings, and the discal ochreous patch in the hind-wing is somewhat smaller in extent. 



The species of Amauris, whilst serving as models for a large number of butterflies of other 

 genera, are by no means exempt from the influence of their own patterns upon each other. 

 This subject has been carefully investigated by Mr. Neave, and the results of the examination 

 were included in his paper on ' Bionomic Notes on Butterflies from the Victoria Nyanza ' 

 (Trans. Ent. Soc, 1906). Here it was shown that both A . ec^m'aand A . albimaculata have been 

 modified in the Victoria Nyanza region by the presence of Amauris psyttalea. In that locality 

 the specimens of echeria are of the jacksoni form, and the examples of albimaculata are repre- 

 sented by the form hanningtoni, Butl., in which the spot in the fore- wing cell is larger, and there 

 is a tendency in both wings towards the appearance of more numerous submarginal spots than 

 in the t3rpe form, a feature common to the damoclides form of A. psyttalea. The discoidal cel- 

 lular spot was measured in a large number of specimens, and it was found that in South African 

 examples of A. echeria the average dimensions of this marking were 2-26 mm. by 1-13 mm., 

 whilst in echeria f. jacksoni these measurements became 3-73 mm. by 1-46 mm. in British East 

 Africa, and 4 05 by 1-525 mm. to the east and north-east of Lake Victoria Nyanza, and to the 

 west of that lake the dimensions were 3-947 mm. by 1-704 mm. Similarly southern examples 

 of albimaculata averaged 2-13 mm. by 1-02 mm. in British East Africa, 3-32 mm. by 1-52 mm., 

 north-east of the lake 3-86 mm. by 1-75 mm., and to the west 3-953 mm. by 2-232 mm. 

 In addition to the evident modification in echeria and albimaculata it is further pointed out 

 that echeria is itself modified as we proceed westwards, so that the pale marking of the hind- 

 wings becomes reduced in area, so as to cause an approach towards A. hecate. Accurate 

 research of this nature is extremely valuable and interesting, as showing with what precision 

 selection may act in the production of Miillerian mimicry. It is not, of course, suggested 

 that insectivorous enemies observe the exact size or even the number of the spots on 

 a butterfly's wing. It is the general effect produced by the markings during flight which 

 is modified by these apparently smaU differences, which, in view of the above facts, must 

 be regarded as of selective value. 



The example of A. echeria on Plate V, Fig. 13, is of the jacksoni form and was taken 

 at Kilimanjaro. The fore-wing spots are much paler than in typical Natal forms, which 

 latter are also generally somewhat smaller. The example of albimaculata is from Durban. 

 It exhibits the smaller size common to the more southern specimens, and the minuteness 

 of the fore-wing cell spot is very well illustrated. 



HYPOLIMNAS DECEPTOR. 



Trimen, Trans. Ent. Soc, p. 105 (1873), 0^. Smith (var. deludens), Rhop. Exot. 43 Hyp., 



— S.Af.Butt.,i,p.286,o^and?,pl.6,f.3(i887). p. 6, pi. 3, ff. 3-5 (1898). 



Hopffer (9 duhia), Peters Reise. Moss. Ins., Butler (kirbyi), Proc. Zool. Soc, p. 51 



p. 385 (1862). (1898) o^. 



Smith (var. deludens), An. N. H. (6), vii, p. 125 Aurivillius, Rhop. Aeth., p. 149 (1898). 



(1891). 



Plate IV, Fig. 17, 



Trimen described both sexes of this butterfly in 1887 and gave a figure of the female. 

 The insect described as H. kirbyi by Butler, in 1898, corresponds with the male of deceptor, 

 as described by the former author, and as such it is now recognized. All possible question 



1200 H 



