The Bionomics of South African Insects. 488 



indications of the white sub-apical bar of clirnsljrpiis can 

 be detected in Idugii, especially at the points on the costa 

 and the hind margin which the two ends of the bar would 

 have reached. Very faint traces of the course of the bar 

 between these two points can be made out in certain 

 individuals (Plato XV, fig. 1), while occasionally they are 

 very distinct, especially upon the under-side (Plate XV, 

 fig. \(i). Looking at these two figures, and comparing 

 tliem with Figs. 1 and la on Plate XIV, it is impossible 

 to resist the conclusion that we see before us the vestiges 

 of a fading character and not the rudiments of a developing 

 one. It is interesting to note that one of the slightly 

 intermediate varieties ofl'Iugii here represented (viz. Fig. 1, 

 Plate XV) was an individual captured by Mr. and Mrs. 

 Hinde at Machakos Road, and that three or four others of 

 the same set showed similar tendencies. It may be that 

 the unfavourable conditions (see pp. 473, 474), although 

 unable to change one form into another, nevertheless 

 administered a shock which caused a slight reversion 

 towards the ancestral type in some individuals. 



The three great mimics of both forms of chrysirjipus, the 

 female of the Nymphaline, Hm^olmmas misi'pints with its 

 inaricc form mimicking Idugii ; the Acra3ine, A. enceclon * 

 with its liugii-Wke. form daira ; the Lycsenid Mimacrxct 

 marshcdli with what I believe to be merely its Idugii-Wke 

 form (Joltertyi, all these show precisely the same thing as 

 their model only in an exaggerated form, because the 

 vanwiQ foUoivs its model and therefore still exhibits stages 

 which the latter has left behind. Comparing the upper- 

 and under-side of the chrysvp23us-\\\ie L3^ca?nid on Plate 

 XIV (Figs. 2 and 2a) with those of the Jdngii-like form 

 on Plate XV (Figs. 2 and 2ft), there can be no doubt 

 that the latter developed from the former. The white 

 bar of marshcdli (Plate XIV) can still be distinctly 

 traced in dohcrtyi (Plate XV), not indeed as a wliite 

 bar but as a very faint paling of the ground-colour 

 over a sub-apical area, the outline of which exactly 



* The first recognition of the mimicry of clwysippus by enccdon, 

 and indeed of the existence of Mtillerian mimicry in the Ethiopian 

 Eegion, was first brought forward at the meeting of the British 

 Association at Toronto in 1897 (Report, p. 689). Aurivillius (Rhop. 

 Etli. 1898, p. 533) states that the resembhxnce had not been previously 

 noticed. The account given by Aurivillius is however far more com- 

 plete than that in the brief abstract here referred to, and is also 

 accompanied by illustrations. 



