tlie Study of the Drepanididse. 565 



first section are of a very different character from those of the 

 second^ between most of which there is a striking general 

 resemblance in this particular. Further^ all the members of 

 the former which are known to me in life [Himatione, 

 Vestiaria, Palmeria, and Drepanorhamphus) have a peculiar 

 noisy flighty so that the sound caused by their wings, when 

 they fly freely, can be heard at a long distance. 



In the second group the primaries are never truncate at 

 the apex; the young, moreover, are invariably clothed to 

 a large extent in green or olivaceous plumage; and this 

 colour nearly always persists in the adult female, although 

 it may be totally lost in the adult male. Such is the case in 

 several species of Loxops, the green coloration in this genus 

 being largely permanent in the male of the Kauaian species 

 only [L. cceruleirostris) . There are almost always well- 

 marked distinctions of colour between the adults of either 

 sex. In a few forms w^hich retain in the adult male and 

 female the green plumage characteristic of immature birds 

 (e. g., Viridunia and Chloridops) there is little or no differ- 

 ence in the colour of the sexes ; but very rarely is this the 

 case when the adults acquire a special coloration, as in 

 Loxioides, in which the head is yellow, though somewhat 

 less brightly coloured in the female. 



To those who believe in the great significance of the very 

 different character of the coloration of the young birds in these 

 two groups (whatever change may take place in the adults), 

 as well as of the development of striking sexual characters 

 throughout nearly the whole of one of them, the necessity of 

 distinguishing clearly between them will be apparent. 



4. Develo^nnent of Species in each Group along similar 

 lines, and the reason for the same. 



When we examine, side by side, a full series of the forms 

 it is obvious at a glance that each group has developed along 

 similar lines. Himatione and Palmeria of the first are in 

 general structure very like Chlorodrepanis and Viridonia of 

 the second ; Drepanis and Drepanorhamphus resemble Hemi- 

 gnathus; Ciridops may be compared with Loxops. 



