PHYLOGENY OF THE PALZOGNATILA AND NEOGNATHA., 193 
The quadrate of Dromeus differs but slightly from that of Casuarius. The outer 
and inner mandibular condyles are on distinctly different levels, the inner being 
ventrad of the outer, shorter from without inwards and wider from before backwards. 
The backwardly projecting condylar spur is less marked and formed entirely by the 
outer condyle. 
The orbital process is less hollowed above. 
In the Dinornithide, e. g. Emeus, the quadrate resembles that of Dromeus in the 
difference of level between the outer and inner mandibular condyles and in the form of 
the orbital process. This processis, however, peculiar in that its whole inner surface is 
requistioned for the articulation of the pterygoid. The inner mandibular condyle is 
peculiar in that the middle region of its articular surface is produced downwards, whilst 
the outer condyle looks more directly downwards than in Dromeus. 
The pneumatic foramen is mesiad, and not posterior. A posterior foramen is, however, 
sometimes present in the Dinornithide. 
In Struthio the inner and outer mandibular condyles are widely separated ; otherwise 
they closely resemble those of Dromeus. ‘The orbital process differs from that of the 
other forms so far described, in that its distal end turns sharply upwards, and in that 
there projects from its inner ventral border a sharply defined articular facet for the 
pterygoid. The otc process is relatively longer than in the other forms. Both the 
mesial and posterior foramina are present, though the latter may apparently be 
sometimes absent. 
In Apyornis the mandibular condyles resemble in form and disposition those of 
Struthio, and in some respects Dinornis. The form of the orbital process seems to have 
differed from ail other genera in its great breadth. Its free end is missing, but from 
the sharp edge of the proximal end it is probable that it articulated with the pterygoid 
as in Struthio. The pneumatic foramen is mesial. The specimen from which this 
description is taken was kindly lent me by Dr. Forsyth Major. 
In Rhea the quadrate resembles that of Dromeus rather closely. The external 
mandibular condyle is broken up into two distinct articular facets. The inner is 
similarly subdivided but not so distinctly; of these two last the outer is vertical and 
looks forwards and outwards, the inner ventral. The ofi¢ process is very short. Its 
articular head has its long axis at right angles to the long axis of the skull. The 
posterior pneumatic foramen lies immediately below the articular condyle. The 
orbital process is very short, blunt, and very wide, it does not project beyond the level 
of its articulation with the quadrate. 
In Crypturi the form of the quadrate is quite peculiar in the development of a 
distinct cingulum projecting backwards above the external mandibular condyle. The 
otic process is bent backwards at a sharp angle, and forms with the orbital process a 
Y-shaped bone. ‘The external form of the orbital process resembles that of Struthio 
but is more slender; the method of articulation with the pterygoid closely resembles 
