to limitations of the Milllerian Hypothesis of Mimicry. Ill 



III. Why do loth sexes of Archonias tereas mimic only 

 the female o/Papilio zacynthus ? 



A second argument for Diaposeraatism has been based 

 on these same two species, considered from a somewhat 

 different standpoint. The case was stated as follows : 

 " So far as I am aware no explanation has yet been offered 

 of the fact that it is the females and not the males of 

 Fapilio polymetus, P. zacynthus, etc., that a.re resembled by 

 Euterpe tereas and E. critias; whereas the males, which 

 display brighter colours, afford at least as good, if not 

 better, models for imitation. I would suggest that this 

 is really due to ' reciprocal mimicry.' The protection 

 gained by the resemblance between the Pierines and the 

 Papilios is not all on the side of the Pierines, but mutual ; 

 and the female Papilios have, as is usual, felt the need of 

 it more urgently than the males. For this reason the 

 female Papilios have been led to meet the Pierines by 

 discarding, or at any rate by not adopting, the bright 

 metallic-blues and greens that ornament the other sex." 

 (Trans. Ent. Soc. 1894, p. 298, note.) 



The colour of the $ P. zacynthtis differs principally from 



that of the $ in that the posterior two-thirds of the 



fore-wing patch is covered with metallic-green or blue 



scales, only the anterior portion being white ; whereas in 



the $ the whole patch is white. The contention for 



reciprocal mimicry here centres entirely on the supposition 



that it is difficult otherwise to explain Avhy the Archonias 



have not acquired the metallic patches of the male 



Papilios. In considering this difficulty the first point 



which suffoests itself is to examine the occurrence of metallic 

 . °~ . . . ... 



colours in other American Pierines. This inquiry reveals 



the interesting fact that not a single one of these has 



developed any metallic colours. The same limitation 



holds good in Asia, as Wallace long ago pointed out, in 



his classical paper on the Eastern Pierines : " The metallic 



blue of Morpho and of the Lycsenidse, and the rich green 



of various shades which occurs in most other groups of 



butterflies are entirely absent " (Trans. Ent. Soc, 1867, p. 



301). In fact, so far as I have been able to ascertain, it is 



only in Africa that any Pierines have developed such 



metallic scaling, and there it is confined to the males of 



only two or three species of Teracoiics. But I cannot find 



that any Pierine mimic has ever produced this type of 



