the Skull of 'Diademodov. 300 



The otli tootli is, with the exception of the inner cusp, 

 well preserved on both sides ; it clo>ely resembles 4, but 

 the outer cusp forms a ridjrc along the outer border of the 

 tootli, which shows faint indications of division into a number 

 of small crenations. 



The Oth tooth, l)est preserved on the left side, is longer 

 and narrower than the 5th ; it has a tendency to a triangular 

 section, being rather shorter on the inner side than 

 externally. 



The outer cusp borders the usual groove and posteriorly 

 is provided \Mth two very small crenations. The posterior 

 surface of the cusp on the right side shows a groove con- 

 tinning a very deep notch in the succeeding tooth : this 

 groove is placed vertically and faces directly backwards. 



The 7th tooth has a very powerful external cusp, which 

 gives origin to a ridge running across the tooth to a low 

 cusp on the inner edge. In advance of this ridge the tooth 

 has a well-marked furrow, which is the continuation of that 

 on the [)Osterior side of the Gth tooth. 



Behind this ridge and somewhat to the outer side of the 

 tooth is another furrow, pointing backwards and standing 

 nearly vertically ; this groove furrows the outer cusp on its 

 posterior surface. 



Tooth 8 has a very strong cusp on the outer side, con- 

 tinning the curve formed by the outer pair of the anterior 

 teeth ; from this cusp, which has a powerfully crenated 

 posterior edge, a very small lobe projects inwards. This 

 lobe is worn downwards so as to continue the groove at the 

 back of tooth 7. This groove has only an outer wall formed 

 by a worn surface on the strong upstanding outer cusp, 

 Tlic inner lobe is restricted to the front of the tooth and gives 

 it a triangular section. 



The last tooth, best preserved on the right side, has a 

 high, powerful, strongly crenated and backwardly bent ens[), 

 which shows no sign of wear; on the inner surface of this 

 cusp a very small inner cusp also unworn, and at the back 

 an equally small posterior cusp. 



The form and direction of the worn grooves on these 

 teeth strongly sugtjest that there was some slight rodent- 

 like longitudinal motion of the lower jaw. Seelcy. from 

 the study of the very similar but less well-preserved 

 dentition of Gomphognathus polyphagus, had already reached 

 the same conclusion. 



Vomer (tig. 3). — The vomer forms the roof of the narial 

 Ann. ct' Mag, N. Hist. Ser. 8. Vol. viii. 21 



