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18. On Some Points in the Structure of tlic Dicynodont Skull. 



By E. BROOM, M.A., D.Sc. 



(Five Text Figs.) 



THE skull on which most of the following observations are based 

 was found on Rhenoster Fontein, a farm at the top of the Molteno 

 Pass north of Beaufort West, and brought to the South African 

 Museum by Dr. Kolbe. It was sent in 1902 to Prof. Seeley, and 

 the matrix was most carefully removed under his direction by the 

 British Museum preparators. He had most carefully examined the 

 skull and traced out the sutures, and intended to give a full descrip- 

 tion, and had prepared for his paper a series of process blocks of 

 drawings of the skull ; but apparently he had not gone further. 

 Doubtless other work which he thought more important, such as 

 the study of the skull of Erythrosuchus, came to hand, and death 

 overtook him with his work unfinished. The skull has been 

 returned to the South African Museum, and as the illustrations 

 have been prepared I have been asked to write a description of the 

 skull to accompany the blocks. Though Prof. Seeley has left no 

 manuscript, so far as I am aware, it is possible to get a good idea of 

 his views from his determinations on the figures. In a number of 

 points my views differ from those of Seeley, and where this is the 

 case I shall give his views as well as my own. 



Though imperfect as regards the right zygomatic arch and 

 slightly crushed and distorted, it is the finest Dicynodont skull 

 that has ever been obtained. Others have been got more complete 

 but owing to the condition of the bone or matrix it has been 

 impossible to display the bones in such perfection, and no skull 

 has ever shown so many sutures satisfactorily. 



As regards the species there is here, as with all Dicynodonts, 

 an element of doubt. In the first place, we do not yet know whether 

 Oudcnodon is not really the female of Dicynodon. Owen, Lydekker, 

 and the writer have all considered the question, and all come to the 

 conclusion that probably the genera are distinct, but as time goes 

 on doubts became greater, and at present the evidence on the two 

 sides is about evenly balanced. Lystrosaurus is apparently tusked 

 in both males and females, while Cistecephalus is tuskless in both 



