28 



from trimeni. We find, in fact, a forewing pattern which is in 

 part that of cenea and in part that of hippocoon, but with all the 

 markings transformed into fulvous orange. Intermediate stages 

 between leighi and planemoides are also found both within the 

 range of planemoides itself and also some hundreds of miles 

 eastward of it and its models (see p. 33). 



The polvtrophiis females have occupied a good deal of our time 

 and attention, but they are of extraordinary interest as showing 

 us the origin of all the mimetic forms of the species. The pattern 

 of the male polytrophus (Plate II, Fig. 3) bears considerable 

 resemblance to the western subspecies dardanus dardanns, but 

 there is, I think, little doubt that polytrophus is in interbreeding 

 connection not only with dardanus dardanus on the west, but 

 with dardanus tibullus on the east. In the forest at a lower 

 elevation (about 5,500 ft.), near Nairobi itself, we meet with a 

 larger form of male bearing heavier markings. At this elevation 

 trimeni is still to be seen — a fine example, captured by the Rev. 

 K. St. Aubyn Rogers, is in the drawer I have just placed upon 

 the frame, with another remarkable form, apparently a mimic 

 of Danaida chrysippus f. dorippus, captured in 1903 by the late 

 Mr. C. F. Elliott.^ There can be no reasonable doubt that these 

 larger specimens of the lower slopes form one interbreeding 

 community with those of the higher, and that tibullus on the 

 east is Syngamie with polytrophus of the lofty Escarpment 

 near Nairobi. 



Before leaving polytrophus I ought to mention that the 

 remarkable ancestral form trimeni appears to belong chiefly to the 

 East African section of the dardanus subspecies ; for it is not only 

 common at Nairobi, but the first specimen to reach a European 

 collection was captured in 1884 by Lieutenant Turner well 

 within the area of tibullus at Zanzibar.- Varieties which I 

 think are to be interpreted as forms of the variable trimeni have 

 been described by Aurivillius from Kibara, to the west of 



^ Trans. Eut. Soc, Loud., 1908, pp. 554-7. The date of capture is 

 erroneously given as " 1893 " on p. 556. A coloured figure of the speci- 

 men may be seen in Eltringham's African Mimetic Butterflies, Oxford. 

 1910, PI. X, Fig. II. Excellent coloured representations of nearly every 

 form of P. dardanus are given on the same plate. 



2 Proc. Ent. Sac, Lond., 1897, PP- Ixxxviii, Ixxxix ; Trans. Ent. 

 Soc, 1906, p. 283, PI. XIX, Fig. I. 



