2 U.S. NATIONAL MUSEUM BULLETIN 2 65 



ment of various degrees of similarity to host eggs by the eggs of 

 different species of glossy cuckoos, and the lack of continuity of 

 pattern found in the development of this favorable adaptation in the 

 phylogeny of the genus Chrysococcyx; 5. the fact, related to the 

 preceding, that various glossy cuckoos show different degrees of 

 egg morphism or the lack of it (one phenotypic egg) ; 6. the enormous 

 diversity of migratory behavior in different segments of the genus 

 and even in regional, geographic portions of the total population of 

 some of the species; 7. a remarkable and, apparently, a fairly abrupt 

 change in the plumage patterns of the young; 8. a great intensifica- 

 tion of sexual dimorphism in the adult plumage in some species of 

 the genus and not in the others; 9. the fact that the genus shows a 

 multidirectional radiation of differentiation, not one main line of 

 progressive alteration from a presumably earUer, more "primitive" 

 to a later, more "advanced" stage. 



As will be seen from the body of this paper, the glossy cuckoos 

 do not reveal any such striking reversal of evolutionary trends as 

 that found among the crested cuckoos. They do present a picture of 

 interest in that they form an ancient group with definite gaps in its 

 composition due to the fact that a number of evolutionary inter- 

 mediates between current species have long since disappeared without 

 a trace. The glossy cuckoos may be numbered among those cases that 

 are all too numerous in nature but that fail to be reported on in detail 

 since they do not lend themselves to as convincing and as readily 

 accepted reconstructions as do others where the steps between all 

 present species are more easily discerned. 



My experience with Chrysococcyx in the field is limited to 3 of the 

 4 African species (the genus contains 12 species in all), and, as will be 

 showTi in this report, these African members of the group probably 

 are phylogenetically the more recent species of the glossy cuckoo 

 assemblage. However, over many years, I have compiled, compared, 

 and studied data on all aspects of the life histories of all the mcluded 

 species, including much unpublished material kindly sent me by 

 cooperative and generous observers. The scattering and haphazard 

 nature of many of these discrete bits of data, and the wide range of 

 accurate detail (or lack of it) in many of them has made it difficult 

 to correlate, appraise, and interpret them, and it has therefore become 

 imperative to undertake a careful synthesis and reconstruction of the 

 past history, vicissitudes, and relationships of the group as a whole. 

 Inasmuch as this reconstruction is basic to our evaluation of brood 

 parasitism in the glossy cuckoos, we may now turn to the composition 

 of the group and to their apparent natural arrangement. 



The data and then* discussion and interpretation are presented in 

 this paper in the following sequence, to give a coherent picture of 



