IQ U.S. NATIONAL MUSEUM BULLETIN 2 65 



As is usual in piiylogenetic reconstructions, there is no concrete 

 evidence by which to prove beyond question which of the foiu- present 

 African species is nearest to the original stock that invaded that 

 continent. Careful comparison of all characters, habits, and dis- 

 tribution makes it probable that the invader is the klaas-flavigularis 

 section. These two closely related species are more like (or less unlike) 

 the Indo-Australian members of the genus than are either caprius 

 or cupreus, and of these two it seems ihsit Jlavigularis is nearer to the 

 original emigre stock to Africa than is klaas. This is, admittedly, as 

 in all such evolutionary conclusions, a judgment rather than a proven 

 fact, and because of its nature as a considered opinion it is essential 

 that the evidence be given in detail at this point. 



The yellow-throated cuckoo, C. Jlavigularis, is a monotypic, very 

 inadequately known, rarely observed, and seldom even collected bird 

 of the west African forest area. Because of its relative rarity in 

 collections, with a resulting paucity of observations on what may be 

 learned from the examination of specimens, C. Jlavigularis merits 

 discussion in some detail here. It is certainly the least known and 

 least adequately reported of the African members of the genus, and it 

 may well be less known than any of the Indo-Australian forms as well. 

 It is restricted to the forests of equatorial Africa, from Sierra Leone 

 in the west, to the Congo-Uganda border in the east, and south to 

 southern Cameroon and the forests of the lower Congo and of the 

 Kasai area. Although it is w^holly restricted to the true forest and does 

 not venture out into the tree-dotted grasslands where its close relative 

 C. klaas is foimd, the latter invades the oviter fringes of the denser 

 forest enough so that the two species are occasionally sympatric. 

 Curry-Lindahl (1960, pp. 111-112) found the two together in the 

 forest at Lwiro, in the eastern Congo. The fact of sympatry is evi- 

 dence of the fully established specific independence of the two, a 

 fact which had not been questioned by anyone in the meager lit- 

 erature oi Jlavigularis, but which may be stressed here nonetheless. 



In its character of barred imderparts in the female and of barred 

 abdomen in the male, Jlavigularis seems somewhat intermediate be- 

 tween the other African glossy cuckoos, where this ventral barring is 

 piu-ely a character of immaturity, and the Asiatic species, maculatus 

 and xanthorhynchus. It cannot be proved, at this late date, whether 

 the stock presentlj^ represented hj Jlavigularis was the original invader 

 of Africa from the Orient, or whether its ventral barring is merely a 

 reappearance or a perpetuation of a basic pattern in the old Chrysococ- 

 cyx stock, using that generic name in the broad sense. The species 

 jlavigularis further agrees with the two mainland Asiatic species in 

 having the bill and feet yellow, not dusky as in its nearest African 

 relative, klaas. In as far as it may be possible to postulate an evolu- 



