590 Transadioyis of the Royal Society of South Africa. 
zygodactyle arrangement of the toes in this and other Psittaci. The hypo- 
tarsus at the postero proximal extremity is extremely narrow from above 
downwards. In macaws this is even more markedly the case, and in these 
birds it has but one large, central perforation for the passage of tendons, 
while in Palaeornis clocilis there are two very distinct small ones. 
In Amazona oratrix this perforation is also single, as it is likewise in 
Leadbeater's Cockatoo {Cacatua leadbeateri) . 
First metatarsal or " accessory metatarsal " for hallux digit in Palaeornis 
small, and, as a matter of fact, is not especially large in the big macaws. 
As to the phalanges of ]pes, they offer nothing of unusual character beyond 
what I have already described for the Psittaci generally in previous papers 
of mine, cited above. That these birds all possess zygodactyle feet, through 
the reversion of the fourth digit, is a fact long known both to systematic 
ornithologists and to avian anatomists. 
Conclusions, 
In so far as the osteology of Palaeornis goes, it would seem that it tends 
to support the views of those taxonomers who claim that the birds of this 
genus, together with other genera, constitute a subfamily — Palaeornithinae. 
This subfamily Garrod placed in a family Palaeornithidae, while R. Bowdler 
Sharpe relegated the same subfamily to the family Psiltacidae, which is 
probably nearer the case than what the first-named classifier seemed to 
believe to be their position in the system. 
This entire group of birds stands much in need of researches upon its 
morphology, and particularly its osteology ; and until this is far more 
exhaustively done than it has been up to the present time (January, 1915), 
we shall not be able to appreciate the natural affinities of many of these 
birds which are now classified upon a few external characters, and, in only 
a limited number, only too few internal structural ones. 
