194 MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 
that of Dinornis. The form of the outer and inner mandibular condyles is not unlike 
that of Dinornis. ‘The inner condyle is, however, more nearly spherical than in any of 
the other forms herein described. 
Apteryx possesses a readily distinguishable quadrate. The height of its vertical axis 
is less than that of a line passing backwards through the orbital process, which is very 
long. 
The articular condyles for the mandible present the same ground type as in Dromeus 
and Casuarius, but the external condyle presents a tendency to split into two facets, 
the region nearest the quadrato-jugal bar being scooped out. The zygomatic process 
of the squamosal is closely applied to the outer side of the quadrate. In Struthio and 
Rhea, it should be mentioned, there is a considerable space between these two points. 
In all the Paleognathe the quadrate is peculiar in that the pterygoidal articulation 
extends upwards on to the orbital process for more than half of its length. 
In Apteryx the articular surface for the pterygoid is rather more sharply defined 
than in the other Palwognathe. Arising at thé base of the internal mandibular 
condyle, it extends outwards on to the inferior border of the base of the orbital process, 
taking the form of a deep hollow into which the pterygoid closely fits. 
The otic process has two fairly distinct articular facets. Superiorly transversely 
elongated, its mesial extremity is expanded into an almost circular head and articulates 
with the pro-étic. Its external extremity runs obliquely down to the shaft towards the 
middle line, and affords an articular surface for the alisphenoid and squamosal. 
The pneumatic posterior aperture is sometimes absent. 
The separation into pro-étic and squamosal heads in the other Palwognathe is only 
very feebly indicated. 
The exoccipital does not contribute towards the articular surface for the quadrate in 
Apteryx. 
The Mandible. (Pl. XLIII. fig. 9.) 
The mandible in Casuarius is long, slender, and sigmoidally curved. Posteriorly, it 
is expanded to afford an articular surface for the quadrate. This is moderately deep, 
and with sloping sides meeting at a sharp angle at the bottom of the fossa. Internally, 
it is produced into a blunt internal angular process. The surface for the external condyle 
forms a long narrow facet running parallel with the external border of the cup; that 
for the inner forms a band-shaped facet, hollow from within outwards. Immediately 
without the inner end of this internal facet is a pneumatic foramen. The posterior 
angular process is only feebly developed. 
In Dromeus the internal and external angular processes are larger than in Caswarius. 
‘The rami are almost straight, and the symphysis is very broad. In other respects the 
jaw agrees with that of Casuarius. In Dinornithide, e. g. Dinornis, the articular 
