• on Mullerian Mimicry and Diaposematism. 577 



has taken place as between these groups, I think that 

 those naturalists who are well acquainted with the species 

 concerned will regard his conclusion as a reductio ad 

 ahsiordum. 



Why do both sexes of Archonias (Euterpe) tereas mimic 

 only the females of Papilio zacynthus ? 



In this section of his paper Mr. Marshall makes the 

 curious statement that " not a single one of the American 

 Pierines has developed any metallic colours" (p. 111). 

 By " metallic colours " he shows in the same passage that 

 he means an iridescence or glow such aS' may be seen 

 in certain African species of Tcracolus, for example in 

 T. I'eyina, where it exists in a highly-developed condition. 

 Has Mr. Marshall ever looked at Dismorphia teresa ? 

 Or at the male of Meganostoma eurydice, or of Colias lesbia 

 and G. vautieri ? Or at a fine male specimen of Phodiis 

 argante ? Even in the Pierine genus at present in 

 question, it is by no means rare for a well-preserved 

 example of Euterpe approximata or E. eritias to exhibit 

 a purple gloss on the hind-wing, a gloss which, though 

 comparatively undeveloped, recalls that of many Papilios. 

 The fore-wings of E. antodyca $ and E. siuainsonii $ often 

 show a similar bloom. Then as to African forms, has Mr. 

 Marshall forgotten Colias electra, of which he must have 

 seen innumerable specimens ? There can I think be no 

 doubt that there is nothing in the Pierine constitution to 

 prevent the development of " metallic " colouring, should 

 the opportunity and need for such development arise in 

 the history of a species. In reference to F. Miiller's 

 statement that although in his experience Euterpe tereas 

 was common, and Fajnlio nephalion rare, the latter must 

 be regarded as the model rather than the former, Mr. 

 Marshall seems to be quite alive to the fact that if this 

 case of mimicry is, as he says, " in every way consistent 

 with the interpretation of a simple Mullerian approach," 

 it remains an instance that prima facie requires a good 

 deal of reconciling with his view as to the improbability 

 of Mlillerian approach even when the numbers are equal, 

 and much more when the numbers of the " model " are 

 inferior. I myself should of course agree with F. Midler 

 that the Pierine has adopted most of its peculiar aspect 

 in imitation of the Papilio ; but I should not consider that 



