Fossil Reptiles. 181 



more marked, so that the posterior and outer border of the 

 squamosal bone makes an angle of about 50° with the middle line. 



The most important new anatomical fact revealed by this 

 skull is the presence of a distinct postfrontal bone. Until recently, 

 the large bone which forms the greater part of the postorbital 

 arch, and a large part of the inner wall of the temporal fossa in 

 Dicynodont reptiles, has been believed to be the postfrontal bone. 

 As in Lystrosaurus, however, there is a narrow bone between this 

 large bone and the frontal, which must be looked upon as the 

 postfrontal, the large bone must be regarded as the postorbital, 

 3S I recently pointed out (Rec. Alb, Mus., Vol. 1., Pt. 1., p. 4). 

 Until now no other Dicynodont reptile than Lystrosaunts has 

 been known to have a distinct postfrontal bone, and it was l)e- 

 lieved to be absent in Dicynodon and Ondetiodon. This little 

 skull of Cudenodon which shows the sutures in this region most 

 beautifully, shows in each side a distinct narrow little postfrontal 

 bone almost exactly as in Lystrosaurus, between the frontal and 

 post-orbital bones, and forming part of the orbital margin. 



Each frontal is a narrow bone which runs back between the 

 anterior process of the parietal and the postfrontal to the level of 

 the parietal foramen. 



The sutures in the anterior part of the skull are not very 

 distinctly seen, and it is, therefore, impossible to describe the 

 dijfferent bones. The snout is rounded and fairly smooth, there 

 being much less elevation of the bones above the nostril than in 

 O. gracilis. 



The nostril is relatively much larger than in O. gracilis, and 

 the antero-posterior measurement is about equal to the distance 

 between the orbit and the nostril. 



The under surface of the skull is very imperfect. The right 

 pterygoid is, however, well preserved. 



I have proposed for this species the name Oudeuodon 

 megalorhinus. 



The following are some of the principal measurements : — 

 Greatest length of the skull, 'ob mm. 



Greatest breadth, 48 mm. 



Length of orbit, IG mm. 



Distance between orbits, 9"5 mm. 



Distance between temporal fossae, l(j%> mm. 



