392 PROF. E. B. POULTON ON BREEDING 



The Geograpliical Distribution and Mimetic Associations of the forms 

 o/Acrgea encedon. 



The account contained in the following four paragraphs was drawn up by 

 the present writer in 1907 but has not hitherto been published. 



Acrcea encedon,\\\e the female of Hypolimnas misippus (Linn.),'presents three 

 forms mimicking the three forms of Danaida chrysippus (Linn.), but, being 

 without the extraordinary powers of flight possessed by the Nymphaline 

 co-mimic, their geographical coincidence with the forms of the model is 

 closer. This superiority is particularly interesting in relation to Milllerian 

 mimicry when we remember that the Acrcdnce are a highly protected group. 



In South Africa the predominant form is encedon, resembling the pre- 

 dominant chrysippus. Dr. Dixey and Dr. LongstafE, from their experience 

 of it in this part of the Region^ state that encedon was " so successful in its 

 mimicry of L. chrysippus as at first to make one of us believe it to be that 

 species^''.* There is also a black and white form, lycia, F., and, even more 

 commonly, a black and yellowish form (sr/auzini, Boisd.) which occur not 

 only here but throughout the East Coast range of encedon. Mr. Marshall 

 has recorded that lycia, when upon the wing, shows a decided resemblance 

 to the whiter forms of Acrcea esebria, Hew.f 



As we pass northwards, forms with white hind wings {alcippina, Auriv.) 

 and forms in which the black and white tip to the fore wing is evanescent 

 (daira, Godm. & Salv.), both rare in the South, begin to increase in numbers, 

 intermixed with the type encedon. Finally, in British East Africa, all three 

 forms occur commonly, daira and encedon being most abundant^ just as 

 are the corresponding models — the dorippus, Klug, and type forms of 

 D. chrysippus. 



In the West, all forms except sganzini occur, but the late Mr. Herbert 

 Druce, F.L.S., received % from a locality in Sierra Leone several specimens 

 of alcippina, which seem to show that the cdcippus form of D. clirysippiis has 

 here at least produced some effect as a model. The specimens in Mr. Druce^s 

 series are not only all alcippina but unusually pronounced examples of this 

 form, and beautiful mimics of the tropical West African form of D. chrysippus. 



H. Eltringham remarks of the distribution of encedon : " None of the 

 forms seems to be specially characteristic of any particular locality, though 

 the alcippina form seems to attain its maximum development in West 

 Africa" (I. c. p. 213). "The lycia, alcippina, and infuscata forms are more 

 numerous in West African localities than elsewhere, though they seem 

 liable to occur elsewhere '' (p. 211). 



« Trans. Ent. Soc. Loud. 1907, p. 318 ; also p. 328. See also p. 321 for the converse 

 inistake, viz. of model for mimic. 



t Trans. Ent. Soc. Lond. 1902, p. 479, 



X Trans, Ent. Soc. Lond. 1902, p. 480. The daii'ct form is extremely rare in the West. 



