Revision of the genus Gytnnorhina. 7 



immature specimen of G. dorsalis, agreeing with one of my skins. 

 It is a bird that, on first sight and without a knowledge of such 

 a phase, might easily be mistaken for G. tibicen. 



In the matter of comparison of the young with the adults, 

 Gould says in his folio work that " the young of G. tibicen 

 assume the plumage of the adult from the nest, and no change 

 takes place from age or season." 



The Brit. Mus. Cat. Bds., vol. viii., p. 92, remarks that {a) is a 

 specimen of G. tibicen, with a back blackish, narrowly-tipped 

 with grey ; that {l>) is a specimen of G. tibicen, with its neck 

 patch not so well defined ; the feathers of the hinder part of the 

 neck being mottled with black ; the feathers of the back, white- 

 edged ; rump feathers with white tips only, producing a mottled 

 appearance. One of these juvenile skins is labelled Queensland? 

 the other Australia. In one of my fledgling skins of G. leuco- 

 nota there is a tendency to shew very little white, and that 

 where it usually appears, on the neck and rump. The above 

 facts alone are enough to shew that the fledglings and young of 

 the eastern species are inconstant, like those of the western form, 

 though to a more limited extent, judging by the small amount of 

 material we have noted. 



G. dorsalis shews its fledglings to be either almost wholly 

 white-backed or black-backed, with phases varying between the 

 extremes, while the immature birds, in certain cases, have 

 distinct, though narrow, blackish "saddles." I should venture 

 to say this phase is the bird referred to by Gould and Ramsay as 

 G. tibicen, and altered (Tab. Lists) later by Dr. Ramsay to G. 

 leuconota. It seems to me that the black-backed variety of 

 Western Australia has not been able to hold its own, failing to 

 become a species, and now merging, if not already so, into G. 

 leuconota. In Central Australia the " black-back " exists, but 

 Avith varieties and " white-backs," through the interior and on 

 three sides of it. AVhether the black-backed variety, at present 

 strongly posted in the south-east of the continent, will fail to 

 survive and become a species seems to me uncertain. On the 

 extreme south-east of Australia and Tasmania the "white- 

 backed " variety, as in Western Australia, has proved itself to be 

 the fittest. Between Southern Victoria and Central Australia 

 the law of natural selection is strongly working to make the 



