Species of the Genus Limenitis. 471 



effected under the influence of troihi.s. The ancestral 

 yellow submarginal spots have darkened, but to a far 

 less extent than in troilus. 



Finally in the turnus form of the female Fapilio r/laucus, 

 only found in a certain proportion of the females in the 

 southern part of the range, we have the youngest of these 

 mimics. The mimetic resemblance is in some respects 

 less perfect than in the other two Papilios, but, as regards 

 the red spots of the hind-wing under surface, it has been 

 already shown that this form presents the closest likeness 

 of the three. 



The evolution of the mimetic pattern of Limenitis 

 (Basilarchia) astyanax from that of the non- 

 mimetic L. arthemis. 



As regards the upper surface of astyanax the main and 

 almost the only difference from arthemis consists in the 

 disappearance of the white band of both wings, together 

 with all but a trace of th6 subapical white markings of 

 the fore-wing, and the spreading of an iridescent blue or 

 greenish tint over and within the area formerly occupied 

 by the band. Towards its inner limits the iridescent tint 

 fades gradually into the dark ground colour of the wings. 

 The iridescence is clearly an extension of the colour- 

 ing seen in the marginal markings of arthemis. The 

 dimorphism in tint — blue or greenish — is characteristic 

 of the ancestral form no less than of its descendant. The 

 reddish submarginal spots commonly seen on the hind 

 wings of arthemis are rarer and far less developed in the 

 specimens of astyanax which I have seen. The converse 

 relationship holds in the fore-Avings, where however the 

 red spots are less developed in astyanax than in the hind- 

 wing of arthemis. 



Upon the under surface the changes are greater ; for 

 not only is there a similar disappearance in astyanax 

 of the white markings of arthemis, but the whole ground 

 colour has become of an iridescent dark greenish-brown, 

 against which the reddish spots near the base of both 

 wings and in their submarginal region, show up very 

 prominently. Although from this cause far more con- 

 spicuous, the submarginal red spots of the hind-wing have 

 become greatly reduced in astyanax, in correspondence 

 with the increase in size of the crescentic black and 



