102 I)r. F. A. Dixey on the phylogenetic 



last is most likely the true explanation, if indeed it is 

 not put beyond doubt by a comparison of the anal 

 angle, under surface, of A. niphe with the same region, 

 either upper or under surface, in P. atalanta. 



A comparison of the upper wings in A. niphe ? and 

 P. atalanta gives a similar result. The submarginal 

 series IV., very distinct in A. niphe, as in nearly all 

 species of the genus Argynnis (fig. 31), is sometimes 

 indicated in P. atalanta with tolerable distinctness, 

 especially in its upper part, and is here seen to be 

 bounded outwardly by an interrupted bluish area like 

 that which in A. niphe bounds the same series of spots, 

 though it is less conspicuous than in the hind wing. 

 Further along the margin of the wing in P. atalanta the 

 same interrupted bluish area occurs, and is here rein- 

 forced by a few scales of a more intense blue, whicli, as 

 we have seen, spread inwards over the centres of the 

 fused dark spots of IV., forming a "blue shade" like 

 those already mentioned, and even reaching and en- 

 croaching on the white spots of series D, a — ^. There 

 can, I think, be little doubt of the substantial identity 

 of series IV. in these two species. 



A. niphe, as far as the arrangement of the black spots 

 on the ground colour is concerned, is quite a typical 

 Argynnis ; and this particular series (IV.) runs in a very 

 well-marked form throughout the genus (fig. 27, &c.). 

 As far, then, as the first constituent of the series of 

 marks we are considering is concerned, i. e., the sub- 

 marginal chain of black spots, we find it well-established 

 in the Fritillaxies, and persisting in a more or less 

 marked degree in the Vanessas. There would seem to 

 be little doubt that, as in the case of the series D, a — ^, 

 we have in Argynnis the generalised or ancestral and in 

 Vanessa the specialised or derived form of the series, 

 and this conclusion is supported by a further investiga- 

 tion into the history of the second constituent, viz., the 

 blue centres and shades. If we are right in tracing 

 back the blue centres to the indications of blue ground 

 colour in A. niphe, it becomes important to ask, What is 

 the meaning of the latter ? 



Now it is a well-known fact that in very many species 

 of Argynnis the two sexes differ in colour, one being 

 much darker than the other. When this is the case the 

 darker is invariably the female. The general darker 

 appearance is partly due to the larger size of the black 



