394 PKOF. T. JEFFERT PAEKER ON THE CRANIAL OSTEOLOGY, 



riorly by an aperture placed in the an^le between the maxilla and the palatine (fig. 63). 

 Its ventral surface forms a nearly flat plate, roughly triangular in form ; its lateral 

 border and postero-lateral angle pass insensibly into the maxilla proper ; its postero- 

 mesial angle is produced into a short recurrent process which articulates with the 

 palatine; the hinder half of its medial border also articulates with the palatine, and its 

 anterior angle and the fore half of its mesial border with the premaxilla. From this 

 flat ventral plate an irregular hollow mass of bone extends dorsad and fits into a space 

 left between the other facial bones at the base of the beak. Its anterior surface 

 appears in the ventro-lateral corner of the external nostril (figs. 7 & 8), articulating 

 with the palatine process of the premaxilla below, with the rostrum mesiad, and with 

 the maxillary processes of the premaxilla and nasal externally. Its dorsal region 

 articulates with the anterior border of the ti'iangular process of the mesethmoid (fig. 8). 

 Its posterior surface, which is smooth and concave, forms part of the anterior wall of 

 the posterior nasal aperture. 



In Emeus the structure of the maxillo-palatine is strikingly different ; its ascending 

 portion, instead of being a hollow shell, is an irregular flattened plate (fig. 64), either 

 quite solid or presenting a mere vestige of the antrum in the form of a very small pit 

 on the posterior surface. By this peculiarity Emeus is sharply distinguished — at least 

 so far as my enquiries go — from the rem aining Dinornithidse 



The Jugal is a slender bone forming the greater part of the dorsal surface of the 

 maxillo-jugal arch (figs. 6 «& 7). It articulates by about the anterior half of its ventral 

 surface with the maxilla, by the posterior half with the quadrato-jugal. Near its 

 posterior end the dorsal edge of the bone is raised into a low triangular process 

 which extends upwards towards the postorbital process of the frontal. 



The quadmio-jugal (figs. 6 &; 7) articulates by more than the anterior half of its 

 outer surface with the jugal and maxilla; thus the whole length of the bone is exposed 

 on the mesial side of the maxillo-jugal arch, while less than half appears on the 

 lateral surface. In the greater part of its extent it is fiattened from side to side, but 

 posteriorly it is much thickened and presents on its inner surface an oval facet for 

 articulation with the quadrate. 



d. The Vomer, Palatine, and Pterygoid. 



The vomer in fully adult specimens of Emeus, species a, and E. crassus is a delicate 

 bone (figs. 2 & 6, vo.) formed of paired laminae united in front but diverging behind, 

 and enclosing an acute dihedral angle. In its whole length it embraces the rostrum ; 

 nteriorly it passes dorsad of the vomerine processes of the premaxilla and articulates 

 with the maxillo-palatines ; posteriorly each lamina turns outwards and fits into a 

 groove between the palatine and pterygoid, its lateral border articulating with the 

 mesial border of the palatine, and its posterior extremity being covered ventrally by the 

 vomerine process (vo.pr.) of that bone. 



