South African Fossil Reptiles and Amphibia. 



159 



are those of D. planus. (Unfortunately, I am not aware of the exact 

 relations of the lachrymal and the state of the occipital conclyle in the 

 type of D. planus.} 



The question then arises Can the relations of the bones in the pre- 

 parieta region be taken as factors of generic, or even of specific, 

 impoi'tance among the many forms of Dicynodon and its allies ? 

 There can be little doubt that the skull (S.A. Mus. 2364) referred to 

 D. planus and that under discussion closely resemble one another in 

 all points save in these relations. Nevertheless, following Dr. Broom's 

 classification, they would be placed in different genera according to 



SM- 



FIG. 38. Chelyrhynchus laclirymalis, Htn. Type. 



of skull. x - 8. 



No. 3334. Side view 



the presence or absence of the preparietal bone. To settle this 

 question, it is necessary to show that the preparietal is constant in 

 any one species, /. e. that forms which agree in all other characters 

 agree also in the possession, shape, .and position of the preparietal. 



In describing the following Auomodont species, Dicynodon platyceps, 

 Dicynodon ictidops, Emydops longiceps, and EmydorhyncJnis palustris, 

 Dr. Broom was able to base his descriptions upon a number of skulls 

 in each case, and in each instance he remarks upon the close agree- 

 ment of the individuals within any one species. Moreover, a long 

 series of skulls in the S.A. Mus. collection referred to Dicynodon 

 jouberti have the preparietal very constant. On the other hand, the 

 two closely-allied skulls 2364 and 3334 differ in that the former has a 



i/ 



long narrow preparietal while the latter is without. 



This skull can be taken as the type of a new genus and may be 



