Revision of the genus GymnorJiina. 3 



upon the other's so-called ground. While it may be proved some 

 day that certain birds are hybrids to the north of the Divide in 

 Victoria, it will not be easy to prove that the so-called hybrids in 

 such a district as Western Port are hybrids. Special attention 

 has been given to the magpies of this latter district by Mr. G. E. 

 Shepherd, with the result that he has never seen other than G. 

 leuconota. Of birds shot at Somerville, examples shew partial 

 reversion to G. tibicen rather than hybridisation. That G. leuco- 

 nota is always larger than G. tibicen is not so. Specimens shew 

 the same dimensions. 



Exaiuples of G. dorsalis handed to me by Mr. A. J. Campbell 

 have slenderer bills, but others collected by the writer near the 

 same locality (Kojonup, W.A.) have bills as deep as those of G. 

 leuconota, while one bill of G. leuconota is as slender and long as 

 in G. dorsalis. Mr. Campbell now believes that the bird 

 described^ by himself as a typical adult female of G. dorsalis 

 was a peculiar immature female, certainly it is not a typical 

 adult female. Possibly it would not have developed beyond the 

 second stage (saddle-back), in which case we would have a 

 permanent black-back )nated with a white-back in Western 

 Australia. 



Although Mr. Gould believed there was sufficient difference 

 between the western bird and G. tibicen to form a new species, 

 an examination of specimens by Dr. Ramsay led him to retain tlie 

 bird in his Tabular List (1888) as G. leuconota. 



The bulk of the black-backed birds appear to occupy the 

 central part of the continent, while the white-backed occupy 

 coastal positions on the eastern and western wings. Reversion, 

 but mostly plumage development from a black to white back, I 

 take it, works in all. 



The various phases of G. dorsalis strongly support G. leuconota 

 as being at the moment our standard magpie, and in placing G. 

 tibicen as a phase of it, it is to be remarked the broad band on 

 the back for one or more generations in some nesting-families 

 remains persistent. The tendency of the fledgling is just as 

 strong to shew a whole white back as it is in other cases to go 

 through the second stage of showing a black band on the back, 



1 Proc. Roy. Soc. Vict. 1895, p. 206. 



lA 



