PURPUREICEPHALUS. 
the head wholly red and the under-surface “ red- blue,” i.e. violet or mauve, 
with the under tail-coverts scarlet. Another curious item is the loss of the 
blue cheeks, exactly as in the Platycercus of West Australia. 
It may be conjectured that Purpureicephalus travelled to West Australia 
at the same time, and in the corresponding stage of evolution, as Platycercus 
did, and developed in that country exactly as that genus seems to have done. 
In the east the birds evolved into Barnardius along parallel lines and then 
wandered westward. Such a theory would account for the presence of the two 
forms in West Australia and would also suggest, as I have constantly advocated, 
that colour pattern is commonly older than structural features. In this case 
we have an extraordinary (for the family) bill evolution, while the colour change 
has been inconsiderable and can be easily seen. 
W 
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