( V ) 



fully emerged from the general dark-blue colour of the wing. 

 The tendency towards a deeper coloration, shown by many 

 female Argynnids, appears to be due to the retention of an 

 old, and not to the acquisition of a new, feature. The 

 successive modifications undergone by the dark spots and the 

 intervening patches of ground-colour, were traced in detail 

 by the help of diagrams, which also exhibited a system of 

 letters and numbers devised by Dr. Dixey for the ready 

 identification of the markings. 



Lord Walsingham said that the lucid manner in which 

 Dr. Dixey had defined the series and groups of markings and 

 the direction in which modifications are found to occur must 

 be of great use in separating true species from mere local 

 varieties ; and that it might be worthy of notice as corrobo- 

 rative evidence that the darker forms are probably the more 

 ancestral and therefore the more glacial, that Vanessa hyber- 

 uates with folded wings, catching the first rays of warmth on 

 its dark under side, whereas the modified Argynnis does not 

 withstand the winter. Lord Walsingham also complimented 

 Dr. Dixey on his excellent drawings and diagrams. 



Mr. Jenner Weir observed that Dr. Dixey's philosophical 

 paper had given him the greatest pleasure, and he was very 

 glad to find that the author attached so much importance to 

 the nearly obsolete markings of some c'l the species dealt 

 with as illustrating their phylogeny, such as the minute blue 

 spot below the ocellus in the under wing of Vanessa io, and 

 the small white spot in the red band of the upper wing, in the 

 female only, of Pyrameis atalanta ; and he observed that Mr. 

 Scudder, in his late work on ' The Butterflies of the Eastern 

 United States,' had not mentioned this mark in his very 

 carefully worded descriptions, and that he had written to 

 him on the subject, to which he replied that he had never 

 observed it in New England specimens. Mr. Weir further 

 said that he thought that the markings on the wings of 

 Apatura iris had a different phylogenetic origin to those of 

 the Argynnidi and Vanessidi ; and he also stated that Dr. 

 Dixey's paper threw considerable light on the mode in which 

 the female of Acidalia niphe had become a mimic of Limnas 

 chrysippus. 



