( cxxxix ) 



We have seen that the evidence of the scent-scales demon- 

 strates that the assemblage known in some arrangements as 

 Mylothris is heterogeneous. We have observed also that the 

 same is true of the South American genus called by Dr. 

 Butler Pieris, and perhaps more usually known as Perrhyhris. 

 It has further been pointed out above that examination of 

 the scent-scales suggests modification of the existing sub- 

 divisions of the old genus Appias or Tachyris. Thus, part of 

 Phrissura seems indistinguishable from Glutophrissa ; while 

 another part, consisting of the Eastern species, is probably 

 more nearly allied to the hippo section of Tachyris ; a third 

 part standing at a little distance from the rest. But the use 

 of the scent-scales in suggesting differences between the . 

 members of assemblages svxpposed to be homogeneous is not 

 confined to genera or subgenera. It can be carried into the 

 domain of reputed species, and is of avail in the discrimina- 

 tion of subspecies or local races. An instance of this is 

 afforded by two forms of Ganoris from the Far East, which, 

 following Mr. Leech, I have been accustomed to rank together-^ 

 under the head of G. melete. But the differences l:)etween 

 their plume-scales are so marked that, as stated in a previous 

 part of this address, the question must be raised whether they 

 are not specifically distinct. It will be recalled that there 

 appears to be an appreciable, though slight, difference in 

 respect of the scent-scales between African and Indian speci- 

 mens of Belenois mesentina, while in addition to a small 

 variation in form there is a marked difference in distribution 

 of the scent-scales between the two geographical races of 

 Leuceronia argia. 



The question may fairly be asked whether any light is 

 thrown by these means on Pierine phylogeny, and whether 

 any conclusions emerge as to the developmental history of the 

 plume- scales themselves. To such questions only a guarded 

 answer can be given. Plume-scales, as is well known, are not 

 confined to the Pierines, but are found in Nymphalines and 

 Satyrines'as well. Pierines are in some respects more ancestral 

 than either of the other groups, and it may be that the origin 

 of the plume-scales is to be sought among the subjects now 

 before us, rather than among the groups which have not been 



