1901.] 



AFETSriTIES OF UDENODON. 



165 



In the follo^\^ng account of the structure of Udenodon, that 

 part dealing with, the skull is founded mainly on the skulls I have 

 obtained at Pearston, while the account of the post-cranial 

 skeleton is mainly based on the little skeleton of Udenodon 

 gracilis. 



Shull. 



The Dicynodont skull has been described by Owen (2), Cope (3), 

 Huxley (4), and others, but the fullest description is that given by 

 Seeley (5). Even Seeley's account, however, leaves many points 

 in doubt, and a considerable number of his determinations are 

 very questionable. I have therefore thought it well to give an 

 independent description of the skull, dealing but briefly with those 

 elements whose structure is well known, and moi'e fully with the 

 points open to dispute. 



Text-fig. 10. 



Text-fig. 11. 



A composite figure of the skull of Udenodon (text-fig. 10) showing details from 

 the left side, for comparison with the skull of a primitive Theriodont, 

 letidosuchus primmvus (text-fig. 11). 



a., angulare ; ar., articulare ; d., dentary ; fr., frontal ; pi., jugal ; fc., lachi-ymal ; 

 mx., maxilla; na., nasal; /;«., parietal; ■p.mx., premaxilla ; ^o/., post- 

 frontal ; pr.f., prefrontal ; c[., quadrate ; sq., squamosal ; s.a., suraugulare. 



