472 Prof. E. B, Poulton on the Mimetic N. American 



iridescent markings lying immediately external to them, 

 and forming an elaborate marginal pattern. It is to be 

 observed that in arthemis itself the tint of the ground 

 colour of the under surface and consequently the degree 

 of prominence of the reddish spots varies very greatly, and 

 that therefore an important element in the change from 

 the ancestral to this mimetic form was pre-existent in 

 the parent species and ready for selection to seize upon. 

 Passing to a very different relationship between the two 

 species, the flight of astyanax is described as similar to 

 that of arthemis, but still more lofty and grand, more- 

 leisurely and sweeping. (Scudder, p. 287.) 



L. ASTYANAX A SECONDARY MIMIC OF THE PaPILIO 

 MIMICS OF PHILENOR. 



Passing now to the mimetic relationships of astyanax, 

 there can be no doubt that the iridescent blue or greenish 

 of its upper surface resembles that of the Papilionine 

 mimics rather than the primary Pharmacophagus model, 

 although it approaches the brilliant steely lustre of the 

 latter somewhat more closely than do the secondary 

 mimics. Of all the thi'ee mimetic Papilios, astyanax 

 chiefly resembles troilns, in which the submarginal cres- 

 centic spots are blue or greenish, instead of dull yellow 

 as in the female asterius, or bright yellow as in the turnus 

 female of glaucus. On the other hand, neglecting this 

 feature, the blue varieties of astyanax would most closely 

 resemble this latter form. These same blue iridescent 

 examples of the Limenitis also resemble the females of 

 troiltLS, in which the black ground colour is powdered with 

 iridescent blue scales, forming a crescentic band inside 

 the submarginal greenish spots. The greenish forms of 

 astyanax similarly resemble the male troilus in which the 

 iridescence is of a peculiar greenish-grey. 



As regards the hind-wing under surface, the submarg- 

 inal reddish spots of astyanax resemble those of the tiirnus 

 female of glaucus less distantly than those of the other 

 Papilios, But the resemblance to any of the three is 

 in this respect only feeble. The basal reddish spots of 

 astyanax may however, with the submarginal series, give 

 something of the effect of the double row of the other two 

 Papilios, or perhaps in the attitude of repose the basal 

 and submarginal reddish spots of the Ziimenitis may be 



