PLATYCERCUS. 
We have here another colour genus which is instructive as a whole and 
I here sketch the chief items. The next genus Barnardius consists of larger 
birds of a different colour pattern, though of similar structure. 
The type of Platycercus , though obviously not the phylogenetic ancestral 
type, is the species P. elegans. The immature, which would be nearest the 
phylogenetic form, is green above with a red cap, blue cheeks, bluish shoulder 
patch, red breast and vent, belly green and tail green above. The immature 
of caledonicus is green above with a red forehead only, blue cheeks, faint 
bluish shoulder patch, yellowish green below and tail green above. This is still 
nearer the coloration of the hypothetical ancestor and we note the accession 
of red in the immature of elegans . The back in both cases is uniform in 
coloration : it is important to note this. 
The mature of caledonicus has retained the red forehead, the head and 
undersurface has developed into a bright greenish yellow ; the back has become 
black with the feathers broadly edged with green, the blue cheeks, blue shoulder 
patch, green tail remaining as in the immature. The green edging to the black 
feathers gives the back a scallopped appearance which is characteristic of the 
genus, of which caledonicus is the most subdued member : though perhaps 
icterotis may be classed near. It is noteworthy that the species which retains 
in the most marked degree the ancestral coloration should be confined to 
Tasmania while the next may be the W T est Australian form. 
The species elegans, with which we began, in its adult state has developed 
into a red bird ; the head, rump and undersurface being scarlet, the back 
having the broad scarlet edges to the black feathers : the tail, however, has 
become blue above, though the blue cheeks and blue shoulder patch are 
retained unchanged. 
The variation in this scarlet coloration is extensive according to locality 
and indicates the instability of the species and its comparatively recent 
evolution. Thus at the Northern and Southern extremes of its present raliige 
the birds are smaller, the scarlet duller and the tipping on the back much more 
restricted in extent : these birds are living in damp and forest conditions. At 
the Eastern limit the red coloration has become paler, a reddish orange, but 
otherwise similar. 
Another species which seems to have evolved simultaneously from the 
basic “ caledonicus ” stock is flaveolus. Here we have the red forehead alone 
retained, the green being replaced by pale yellow, the tail, however, becoming 
blue while the blue cheeks and blue shoulder patch have not altered. 
To be classed here is the Western icterotis , the only member of the genus 
found in Western Australia. The variation seen has caused a lot of confusion 
which will be detailed later. Here the head and undersurface has become 
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