BEDROCK 



Danaines shown in Plate I., Figs. 2, 3, 4, and 5, is an astounding 

 hypothesis, and one which could never have been advanced by a 

 writer who had studied all that is known of the dardanus group. 

 A large amount of evidence has been simply ignored by Professor 

 Punnett, and I can only assume that he is unaware of its existence. 

 It will appear in the succeeding paragraphs that the past history 

 of these mimetic forms can be reconstructed with singular complete- 

 ness from essential phases of the past which still survive in certain 

 parts of the vast range of the dardanus group. 



Trimen, in his original paper, pointed out that Papilio meriones 

 of Madagascar (Plate II., Figs. 1 and 2) gives us a picture of the 

 ancestral non-mimetic form, and he suggested that the black 

 marking on the front, or, as it is called, the costal margin of the fore 

 wing of the female (Fig. 2), was the origin of the bar which is the 

 characteristic feature of the hippocoon form. A little later another 

 non-mimetic species, P. humbloti, was discovered in the Comoro 

 Islands, and a third, P. antinorii, in Abyssinia and Somaliland. 

 In both of these the female bears a black costal marking correspond- 

 ing with that of the female meriones. The essential discovery of 

 forms linking the above three non-mimetic females with hippocoon, 

 the most ancestral of the mimics, was due to the fine collection made 

 in 1900 on the Kikuyu Escarpment, near Nairobi, by the late W. 

 Doherty. Here, on the heights forming the eastern boundary of 

 the Rift Valley, the most interesting series of ancestral females has 

 been preserved. Chief among them is the trimeni form (Plate II., 

 Figs. 6 and 7), winch preserves for us just the stage predicted by 

 Trimen. In some specimens (Fig. 6) the bar crossing the fore wing 

 is barely complete, in others (Fig. 7) it is nearly as fully formed as 

 in hippocoon (Fig. 8). The colour is still pale yellow, although, 

 as in meriones (Fig. 2), dingier than that of the male. But perhaps 

 the most interesting ancestral feature is the retention in some speci- 

 mens of trimeni (Fig. 6) of a rudimentary " tail " to the hind wing, 

 and it is significant that hippocoon is the only mimetic form which 

 I have hitherto been able to find with rudimentary " tails." Such 

 vestiges are to be seen in two examples of hippocoon in the British 

 Museum, and they appeared in two specimens of the family first bred 

 by Mr. Lamborn. I then suggested that he should try the effect of ice 

 upon the pupse of a family. The experiment was very difficult to 



48 



