BY C. 



1069 



has become a long outwardly sloping area forming with the hinder 

 end of the intra-coronoid groove a broad surface for muscular 

 insertion ; its angle is more acute and sharply labiate. The 

 convexity of the hinder part of the inner mandibular wall is much 

 more pronounced consequent upon the development of the fsings 

 of the posterior molars ; the concavity beneath is therefore 

 apparently greater, but the reflection of the angle remains as 

 feeble as before ; absorption resulting from compression, itself the 

 result of the forward march of the molars, has removed so much 

 of the ante- and post-talons that the entire length of the series is 

 considerably reduced. Since, however, the youngest tooth m" is 

 on one side nearly worn down to its basal ridge while the premolar 

 is still in place and function with its fangs intact, it is probable 

 that the forward movement of the teeth is not a rapid one ; and 

 from the position of the outlet of the dental canal beneath the 

 forefang of the premolar compared with its position in the much 

 younger individual in which it is- barely anterior to that 

 fang, it would seem probable that the progression of the 

 teeth in Nototherium is never carried on to the same 

 extent as in the deciduous-toothed Macropods. The extero. 

 lateral ridge of m^ sends up a vertical process on the 

 hinder lobe and, running further across the fore lobe than in the 

 younger example, forms with the adjacent edge of the ante-talon a 

 low flat process on that lobe also ; showing that its condition is 

 liable to individual variation. The premolar is planed down to 

 its base, but enough enamel remains to show as on a plan the 

 limitations of its original form, the single lobe with its pre-basal 

 ridge or lip and post basal talon; on the inner angle of this, 

 however, a flat surface has been formed which, without the 

 teaching of the more perfect tooth, would have suggested the 

 former presence of a tubercle or small lobe in that position. 



External height to basal ridge of ur ... ... 98 mm. 



Length of molar series ... ... ... ... 166 mm. 



Length of m''... ... ... ... ... ... 41mm. 



Height to sigmoid notch ... ... ... ... 203 mm. 



Length from p'' to back of condylar process ... 287 mm. 



68 



