58 Zoological Society. 



the great extension, upwards and backwards, of the broad and un- 

 divided inferior condyle : there is also an articular surface, on its 

 outer side, for the mastoid process (not present in Otis) and another 

 small one on the inner side for the pterygoid ; besides the lower and 

 outer cup for the end of the slender zygoma (squamosal). 



The inner angle of the expanded articular end of the lower jaw 

 of Dinornis ends by a short obtuse process. In Otis and Didus it 

 forms a strong trihedral process, the anterior and posterior facets 

 meeting a transverse ridge below, which is continued into a com- 

 pressed plate forming the posterior angle of the jaw. The posterior 

 surface is smooth and slightly concave, semioval in Dinornis, deeper 

 and subtriangular in Didus. 



The outer part of the articular end of the mandible is smooth and 

 convex in Dinornis : in Didus a masseteric ridge is continued down- 

 wards and forwards from the outer overhanging border of the arti- 

 cular cavity to the back and lower angle of the dentary piece, de- 

 fining, with the posterior border of the dentary, a concave, slightly 

 pitted surface. The surangular in Dinornis has a short and low thick 

 coronoid ridge, external to which there is a rough oval surface. In 

 Didus the surangular developes a very small coronoid process, and 

 its fore-part is deeply notched : a deeper and more angular notch 

 divides the surangular from the angular piece. This notch receives 

 the lower fork of the dentary on the outside, and the end of the 

 splenial at the inner side. These notches do not exist in Dinornis : 

 the surangular, angular and articular pieces have coalesced together 

 in both the extinct birds. Where they join the posterior forks of 

 the dentary piece, a long narrow vacuity is left, which in Dinornis is 

 almost divided by a broad bar of bone extending upwards from the 

 angular, but which does not quite touch the surangular. In Didus 

 the upper fork of the dentary joins the upper and fore part of the 

 surangular; the notch between the hinder forks of the dentary bounds 

 anteriorly the narrow elliptic vacuity, 15 millimeters long by 3 milli- 

 meters deep. A notch also extends forwards, and divides outwardly 

 the symphysial from the ramal part of the dentary : this notch or 

 hole does not exist in Dinornis. 



The parts of the bones of the beak referred to Palapteryx consist 

 of the anterior end of the premaxillary and of the symphysis and 

 part of both rami of the mandible. The premaxillary, by the proxi- 

 mity of the external nostrils to its apex, and by the nasal grooves 

 continued thither on each side from the anterior boundary of the 

 nostrils, resembles that of the large existing Struthionidae, and the 

 Emeu more especially by the slenderness of the nasal process of the 

 premaxillary and the angle at which it rises from the broad and flat 

 maxillary processes. The end of the beak was, however, more obtuse 

 than in the Emeu, and the short symphysis of the lower jaw is more 

 deeply excavated above : it presents, however, the two parallel lon- 

 gitudinal grooves on its under part, as in the Emeu and Ostrich. 

 The lower jaw appears from the remains of one ramus to have been 

 5 inches or b\ inches in length, and to have been broader and deeper 

 than in the Ostrich or Emeu : and the cranium by its greater breadth 



