THE BIRDS OP AUSTRALIA. 
results will coincide. Messrs. Rothschild and Hartert apparently considered 
it too much trouble to do this but wrote their criticism instead. I fail to see 
that they have added to our knowledge of the subject by this contribution. 
It must be remembered that in the present case we are dealing with a bird 
which shows no change of plumage from immature to adult, no sexual or 
seasonal change. Consequently it is difficult to gauge the age of a bird and 
it is certain that the birds grow larger with age. Such a bird needs prolonged 
study and much consideration but rarely gets it. 
If a series from New Zealand be examined, bearing the above fact in 
mind, in comparison with a series from Australia, they will be found to 
average larger. New Zealand is the type locality of Anas superciliosa, and 
when I introduced Anas superciliosa rogersi I regarded East Australian birds 
as typical. Hence my conclusion that the West Australian birds were 
larger. I now unite both East and West Australian forms as differing from 
the Neozelanic form, and would note that the former are generally lighter 
in coloration. 
In the same place Rothschild and Hartert offer remarks on two other 
matters, and I think a few words may be here given in connection with those. 
It does not appear to aid much in the advancement of scientific knowledge 
to enter into discussion with regard to debatable points, especially when no 
new facts are introduced into the arguments. Thus, Rothschild and Hartert 
dismiss my hypothesis in connection with “ Demegretta sacra,’ ^ accepting 
that name and simply noting that I appeared to have overlooked the fact 
that Dr. Heinroth had taken a white bird and a grey one from the same nest, 
and that other Herons present more or less similar dichromatism. They 
conclude it would simply be the upholding of one theory against another, 
which has many more probabilities in its favour. In making this statement 
they do not appear to have studied the facts I produced nor did they work 
at the collection of Herons in the British Museum. If they had done so 
with careful criticism of the material available they might have rearranged 
their ideas. My own conclusions were arrived at by a fair consideration of 
the specimens at hand in conjunction with the reports of reliable bird- 
observers. The rejection of my theory without contravention of my 
arguments, without study of much material and without consideration of 
the facts themselves, is not conducive to much advancement. Of course, the 
fact that no white birds appear in New Zealand is minimised, and they give 
their reading of the Crow question. Thus they state that the two Crows 
{Corvus cornix and G. corone) inhabit strictly limited areas and inter-breed 
only when they meet. When the distribution of the Herons (called Demigretta 
sacra by Rothschild and Hartert) is accurately worked out, the same facts 
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