474 Prof. E. B. Poulton on the Mimetic N. American 



hybrid offspring are produced. If this be so it would 

 constitute further evidence of the close affinity between 

 these three forms, and of the recent operations of the 

 selective processes by which the two mimics have been 

 derived from their non-mimetic ancestor. 



ArGYNNIS (SeMNOPSYCHE) DIANA (FEMALE) A TERTIARY 

 MIMIC OF LiMENlTis ASTYANAX. — This interesting case 

 of mimicry was, so far as I am aware, first suggested by 

 Scudder, who was much puzzled by it. This distinguished 

 authority remarks concerning diana that although it 

 belongs to a group remarkable for resemblance between 

 the sexes, its sexes are more strongly contrasted than those 

 of perhaps any other butterfly in North America. " This 

 difierence, as we have pointed out in the body of this 

 work, is a clear case of parastatic mimicry, the mimicry 

 affecting the female only (as most in need of such pro- 

 tection), and is the more surprising since the butterfly 

 mimicked belongs to the only genus in our fauna, where, 

 in other species, parastatic mimicry of a Euploeid butterfly 

 occurs. If a butterfly of the genus Basilarchia needs 

 protection and gains it by mimicry of Anosia or Tasitia, 

 why should Semnopsycho take to imitating a normal 

 Basilarchia ? That it does closely resemble it any one 

 can see, and tlie following passage from Edwards, writing 

 of the discovery of the female, may be taken in evidence : 

 ' While breaking my way through a dense thicket of 

 [iron-weed], hoping to find another diana [male], I came 

 suddenly upon a large black and blue butterfly, feeding so 

 quietly as to allow me to stand near it some seconds and 

 watch its motions. It seemed to be a new species of 

 Limenitis [Basilarchia], allied to Ursula [astyanax], which 

 it resembled in color.' It may also be pointed out that 

 its range is altogether included within that of Basilarchia 

 astyanax" (I.e., p. 1802). Although the obvious inter- 

 pretation of this interesting resemblance on the probable 

 hypothesis that Jyimenitis (Basilarchia) is a distasteful 

 genus and its mimicry of Anosia Miillerian, seems to have 

 escaped Scudder in this passage and on p. 718, he else- 

 where suggests (on p. 2G6) that astyanax may be specially 

 protected : — " It is indeed possible that one of the 

 normally colored species of Basilarchia, one that has 

 least conspicuously contrasted colors, though resplendent 

 with blue and green, is specially protected by the various 



