INTRODUCTION. 



The study of this very beautiful group of Butterflies seems to be beset with 

 difficulties. Some strange anomalies attend them. Characters which in other 

 groups would be considered significant, seem here to mean nothing. Of two 

 species, of which it would require the best skill of the artist to show the 

 difference, the male of one has on the underside of the anterior wing a tuft of 

 long hair attached to the inner margin, whilst the other is without it. Of two 

 other species equally alike, one has a spot on the centre of the anterior wing 

 (formed usually by the different disposition of the scales) which can some- 

 times be seen only in one particular light, whilst the other, so nearly allied to 

 it that it requires an accurate eye to note the difference, is without it. 



The palpi differ greatly in length in the sexes of the same species ; and of 

 two butterflies which are far too nearly allied to be separated by more than 

 specific distinction, one has the last joint unusually long, whilst in the other it 

 is scarcely visible. The branches from the subcostal nervure, which are such 

 an assistance in determining the position of genera with regard to each other 

 in other families, here avail little, and differ in the sexes of the same species. 

 The sexes, although they differ widely from each other above, are, most 

 fortunately, very constant on the underside. 



