the xS/at?? q/'Diadeinodon. 307 



inwards wliicb is bounded by tbe maxilla, transverse bone, 

 and A'Cry slightly by tbe pterygoid in a ventral view, but is 

 largely covered by tbe pterygoid dorsally (Hg. 3). 



How much of tbe postorbital bar is formed l)y tbe jugal 

 is uncertain. 



Ectopterygoid. — Tbe transverse bone is a very small 

 L-shaped bone, united by a ratber loose suture with the 

 pterygoid, bounded laterally by the jugal and anteriorly by 

 a short contact witb tbe maxilla and a rather longer one 

 with tbe palatine. 



Its inner border at tbe corner of the L forms tbe outer 

 and posterior edges of tbe very small suborbital foramen ; 

 the rest of the lower limb of the bone is joined by the 

 palatine. 



The bone appears to be completely overlaid dorsally by 

 the pterygoid. 



Palatine. — The palatines are widely separated from one 

 another by the vomer (fig. 3). Each may be described 

 as consisting of two parts, the main body of tbe bone and 

 the secondary plate. Tbe body of the bone is an almost 

 vertically placed plate of bone united below to tlie vomer and 

 forming tbe side wall of the great canal of the posterior 

 nares. The postero-lateral corner of this plate is reflected 

 upwards so as to be nearly horizontal in position, and unites 

 with the pterygoid and transverse bone. The lower border 

 of this bone stands up as a ridge lying parallel to and just 

 within the teeth ; it is continuous with the posterior border 

 of the secondary plate of the palatine. The secondary 

 plates of the palatines form toj;ether the floor of the narial 

 passage, and their posterior borders meet at a circular angle 

 of about 100°. 



The scondary plate bears a patch of very small irregular 

 granules which appear to have enamelled tips ; these lie near 

 the middle line and towards tbe back. There seems to be 

 little doubt that these granules are homologous with the 

 palatal teeth described by Seeley in Cynoynathus. The 

 secondary plates of the palatines unite in front with the 

 similar plates of the maxillse, but I cannot be certain of the 

 sutures. 



Maxilla. — The ujaxillse are broken off" anteriorly, but their 

 posterior relations are well shown. Each consists of a 

 massive alveolar part which receives the roots of the molar 



