208 MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 
shifting which brings its proximal end more or less immediately under the antorbital 
plate—appears to have been accompanied by a similar shifting of the palatines, since 
these no longer are connected with the main body of the pterygoid bone but with its 
distal end. This, as we have already shown, ultimately fractures and fuses with the 
palatine, a joint forming at the line of fracture. ‘This connection of the palatine and 
pterygoid by means of a joint is a point of great difference between Paleo- and 
Neognathine skulls. 
In the Zinamide we have an intermediate stage between the Palwo- and the Neo- 
gnathe. The vomer is undoubtedly relatively shorter posteriorly than in Rhea, its 
free end lying midway between the level of the antorbital plate and the basipterygoid 
processes. The pterygoid has increased in length, so that the vomer and palatine 
articulate with its distal extremity only. The quadrato-jugal fossa has also increased 
in length relatively, extending forwards now beyond the level of the antorbital plate 
as far as the vestigial maxillo-nasal process. 
A careful study of these points will greatly facilitate the conviction that the 
egithognathous and schizognathous skulls are but modifications of the dromeognathous 
type. The desmognathous is a further modification of the schizognathous palate. 
The single-headed otic process of the quadrate in the Palwognathe, upon which 
so much stress has hitherto been laid, appears to have less importance than the points 
to which attention has just been drawn, for in Apterysx the otic process is two-headed, 
as in Neognathe. 
Tue VERTEBRAL CoLuUMN. 
The memoirs of Owen, Mivart, and T. J. Parker on the vertebral column of the 
struthious skeleton render it quite unnecessary to do more than briefly comment 
thereon here. 
a. The Presynsacral Vertebre. 
All the presynsacral vertebre of the Palwognathe are heteroccelous, and all of 
this region are free except in the Zinamid@, in which certain of the thoracic 
vertebre fuse. 
The vertebre of Dromcus are the least specialized in type; those of Caswarius are 
very similar. 
Both in Dromeus and Casuarius the cervical vertebre are conspicuously shortened 
antero-posteriorly. In Causwarius the neural spine, traced from the head backwards, 
undergoes considerable change of form. Anteriorly it is little more then a median 
tubercle rising from the centre of a flat neural plate. At about the 6th vertebra it 
sends backwards a pair of low ridges which terminate in a pair of hyperapophyses. 
At about the 10th vertebra, the spine has exchanged its <-shape for a transversely 
crescentic form. ‘This, for the next 4-5 vertebrae, becomes broken across in the middle 
