PHYLOGENY OF THE PALZOGNATH# AND NEOGNATH #&. 207 
relation to the pterygoid has also changed, for they no longer are connected with its 
outer border but by this same inward movement have come to underlie it. 
In the Neognathe, the inward movement has attained its maximum, the palatines 
meeting one another mesially, as we have just remarked, thrusting the vomer forwards 
in so doing. As a matter of fact, however, as we have already shown in earlier papers 
[82], this is not altogether the case. In the young bird the pterygoid extends 
forwards in a spike-like form, much as in Rhea, so as to articulate with the vomer, 
though but by the slightest contact. The palatines have succeeded in moving inwards 
beneath these anterior pterygoid ends so as to all but entirely sever the original 
relations between them and the vomer. 
Later in life (soon after hatching) the severance is complete. At this stage, the 
anterior end of the pterygoid fractures at a point corresponding with the free end of 
the palatine. The fracture later becomes a true joint, and the anterior end of the 
pterygoid resting upon the palatine gradually merges with.this bone so as to obliterate 
all traces of its original existence. ‘Thus the free pterygoid of the Meognathe is a 
secondary feature, the palato-pterygdid connection in the late embryo not differing ~ 
materially from that of the Palwoynathw. Further, the apparent isolation of the 
vomer from the pterygoid in the Neognathe is seen to be a ccenogenetic character, 
so that the palate of this group is brought into close relation with that of the 
Palwognathe. 
A further point of interest in this comparison between the Palao- and Neognathine 
skull is the change which the vomer in the latter has undergone in relation to the 
parasphenoidal rostrum, a change which indicates a shortening both of vomer and 
rostrum. 
The vomer in the Neognathe rarely extends backwards beyond the base of the 
antorbital plate, in the Palewognathe it may reach nearly as far as the basipterygoid 
processes. This is an undoubted proof of the shortening of the vomer. 
That the rostrum has also undergone a considerable shortening is shown by the fact 
that in the Palwognathe it extends forwards for a very considerable distance beyond 
the level of the lachrymo-nasal fossa, in the Meognathw it commonly ends in the 
region of the antorbital plate. 
Yet other evidences of shifting and modification of the dromognathous palate 
reveal themselves in the Meognathe when we come to closely compare them, and 
whilst these show how closely the two groups are related they show still more the 
lower grade of type persistent in the Palwognathe. 
In the Palwognathe the free ends of the basipterygoid processes articulate with 
the extreme proximal end of the pterygoid quite close to the articulation with the 
quadrate. In Neognathe these processes, when present, have shifted forwards on to 
the rostrum, so as to articulate with the middle of the pterygoid. 
The forward shifting of the Neognathine vomer, which we have already noticed—a 
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