3 



damp summer, is probably an incipient mimic of an 

 Acrsean type of colour and markings. Mr. Marshall has 

 suggested that natalensis presents many similarities to Acrcea 

 acara, Hew., especially upon the under side of the wings. 

 The resemblance is probably closer when the insects are flying, 

 the most noticeable difference being in the shape of the 

 wings. 



" It is in favour of this interpretation that a comparison 

 with allied species of Precis tends to show that the blue form 

 is ancestral and the red a recent departure ; furthermore, the 

 latter differs from the former and all its allies in the general 

 similarity of the upper and under sides of the wings — a 

 characteristic of the Acrseinpe, as of all specially protected 

 groups of butterflies. 



" Mr. Marshall's suggestions command increased confidence 

 because of his intimate knowledge of the habits of the two 

 forms. His description of the wide differences therein, as 

 well as in their appearance, is full of interest. The red 

 natalensis is described as frequenting higher and more open 

 country, while sesamus is found in shady places and gardens, 

 and is distinctly warier and more difficult of approach when 

 not feeding. 



" Problems of the deepest interest remain to be attacked. 



of greater stress, viz., the dry winter .season. But in England, 

 although there are abundant examples of insects with warning 

 colouring and many which mimic them in the summer, when there 

 is a plentiful supply of palatable food, in winter none are to be 

 seen. Those, such as Coccinellidae, which exist in the perfect form, 

 hide themselves. The reason probably is that the amount of palat- 

 able food available is not sufficient to make it safe to rely on 

 unpalatability, accompanied by warning colouring. Experiments 

 with hungry animals support this view. It is possible that the con- 

 ditions are similar in S. Africa, and that warning colours are more 

 characteristic of the wet than of the dry season, thus affoiding 

 greater opportunities for mimetic resemblance. If it should here- 

 after be shown that Precis is to some extent unpalatable, and that 

 its resemblance to an Acrsean type is synaposematic rather than 

 pseudaposematic, the parallelism with our own fauna would be even 

 closer, the conspicuous species which hide and thus adopt procryptic 

 habits being represented by one which gives rise to another brood 

 •with markedly procryptic colouring and habits. It should be noted, 

 however, that Mr. Marshall (l.c.)^is strongly of opinion that the 

 species is not unpalatable, and that the colours of the summer form 

 are not aposematic, — E. B. Poulton, November, 1898. 



