South African Fossil Reptiles and Amphibia. 



145 



the foramen is sunken but is surrounded by a slightly raised rim of 

 bone. 



In each skull the pieparietal stands well above the level of the 

 frontals on either side of it. The smaller skull has a very large, 

 lozenge-shaped preparietal whose anterior end is considerably in 

 advance of the postorbital bar. The preparietal of the other is shorter. 

 The bone almost completely surrounds the pineal foramen. 



The frontals meet the nasals in a straight suture at the level of the 

 front of the orbit. Posteriorly they flank the preparietal for a long 

 distance, and each is hollowed out at the side of that bone. The post- 



r.P. 



P.O. 



FIG. 34. Dicynodon laticeps, Br. Skull, No. 3328 (Young). Preparietal 



frontal is a long, narrow bone, which iu each specimen occupies a 

 somewhat sunken area between the frontal and postorbital. 



The chief changes which seem to take place with increasing age, 

 therefore, are the development of the nasal and prefrontal bosses, the 

 sinkiug-in of the pineal foramen, and the decrease in size of the pre- 

 parietal bone. Since the size and shape of this bone in the larger skull 

 seems to agree exactly with that in the type specimen we can scarcely 

 look upon the difference in size as an individual feature, but must 

 reckon it as the result of a change due to age. 



Other interesting features of the larger (and more complete) skull 

 are the short, broad palate, the large tusks, the very strong keel formed 

 by the pterygoids behind the posterior narial fossa, the narrowness 

 between the quadrates, the large tabulare seen on the back of the 



