RAPTORES. 39 



any other member of tlie Raptorial Order — the point at issue 

 being whether it be distinct or merely an albino variety of the 

 Astiir Rail. I have seen both birds in a state of nature, and 

 critically examined numerous examples after death with re- 

 gard to size, admeasurement, &c.; and, except in colouring, 

 I found no difference whatever between the beautiful snow- 

 white bird and the grey-backed individuals so frecpiently shot 

 in the brushes of the eastern parts of Australia. Mr. Ronald 

 C. Gunn and the Rev. T. J. Ewing, of Tasmania, however, 

 incline to believe them distinct, and, in support of this opinion, 

 call attention to the fact that none but white birds have 

 been found in that island ; but while I admit this to be 

 true, I do not fail to recollect that the most lovely individual 

 I ever shot in Tasmania had fiery-red irides ; still it is only 

 fair to state they were not pink as in albinoes, and that most 

 frequently the irides are bright yellow ; the colouring of those 

 organs therefore is evidently inconstant, and not to be depended 

 upon as a characteristic. We know little or nothing of the 

 nidification of either of the birds : could it be ascertained that 

 the grey-backed and the white individuals mate with each 

 other, they should be considered as identical ; but until then it 

 will be better, perhaps, to keep them distinct. Cuvier has 

 hazarded the opinion that the white bird is an albino vaiiety 

 which has become permanent, and that they have the power 

 of perpetuating their white vesture. 



I think Professor Kaup is right in proposing a new generic 

 title for this form, differing as it does both in structure and 

 habits from the true Asturs, of which the A. palumbarius is 

 the type. 



The sexes differ very considerably in size, the male being 

 scarcely more than two-thirds the size of the female. 



The whole of the plumage pure white ; cere and legs yellow ; 

 bill and claws black. 



