1895.] 4bi [Cope. 



directed a little inwards anteriorly if truly anteroposteriorly. Dentine 

 equally thick all round. Extremities of section regularly rounded. This 

 tooth is like the corresponding one of the M. harlanii, and with a greater 

 anteroposterior diameter than in the M. robustus. The third molar is reni- 

 form in section, wider anteriorly than posteriorly, the long diameter 

 directed a little outwards anteriorly from strictly longitudinal. The pos- 

 terior lobe is narrower than the anterior measured transversely, and 

 neither lobe is flattened or truncate at any point. There are tvv^o longitu- 

 dinal shallow grooves of the shaft ; one submedian interior, the other 

 opposite to it, presenting outwards and backwards at an angle of 45° to 

 the axis of the jaw. This tooth is quite diflferent in form from the corre- 

 sponding one in the M. robustus and M. Jiarlanii, in its relatively much 

 greater anteroposterior diameter, approaching in this respect the form of 

 the second superior molar. 



The fourth superior molar has a subtriangular section, the apex external 

 and rounded, and the base internal and bilobate. The posteroexternal 

 face is slightly concave, and the anterior face is flat. Its anteroposterior 

 diameter is relatively greater than in the M. Jiarlanii, agreeing in this 

 respect with the 3i. robustus. It is thus evident that the third and fourth 

 superior molars of the M. renidens are of very different shape, while in 

 the M. robustus they are much alike. The fifth and last superior molar is 

 much like that of the other two species. It is widened anteriorly, and 

 narrowed posteriori}^ the anterior long diameter being 45° to that of the 

 jaw. A shallow groove of the shaft both externally and internally. The 

 area of the grinding face is less than that of the fourth molar. 



The infraorbital foramen issues opposite the anterior half of the third 

 superior molar. The anterior border of the zygomatic foramen is oppo- 

 site the anterior border of the m. 5. The palate is roughened with low 

 ridges and tuberosities. Tlie difference between its anterior and posterior 

 diameters is not nearly so great as in the M. robustus, since the dental 

 series is only slightly divergent forwards from the median palatal suture. 



Measurements of Superior Dentition. mm. 



Length of maxillary bone on palate 128 



Palatal width of maxillary at m. i 35 



" " " at m. iv 26 



anteroposterior 23 



transverse 11.5 



Diameters of m. ii 



Diameters of m. iii S ^°t^'"«P«^^«"°'" ^1 



t transverse at middle 13 



Diameters of m. iv \ anteroposterior (internal) 15 



c transverse (anterior) 15 



Diameters of m. V j anteroposterior 16 



( transverse (45° to long axis) 14 



A fragment from the anterior extremity of the right maxillary bone 

 of another specimen contains the first molar. The bone does not extend 



