PHYLOGENT OP THE PAL^EOGNATHJi AND NEOGNATH2E. 193 



The quadrate of Dromceus 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 Dinornithidce, e. g. Emeus, the quadrate resembles that of Dromceus in the 

 difference of level between the outer and inner mandibular condyles and in the form of 

 the orbital process. This process is, 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 Dromceus. 



The pneumatic foramen is mesiad, and not posterior. A posterior foramen is, however, 

 sometimes present in the Dinornithidce. 



In Struthio the inner and outer mandibular condyles are widely separated ; otherwise 

 they closely resemble those of Dromceus. 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 otic 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 JEpyornis 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 all 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 Dromceus 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 otic 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 



