TET11ABELODON. 



29 



in position in old animals. It is in the lower jaw, how- 

 ever, that the chief changes have taken place. Here the 



Fig. 17. 



Mandible of Tetrabelodon (Rhynchotheriuni) dinotherioides, from the 

 Loup Fork Beds, North-Western Kansas. 



A. Eight side of mandible. iV nat. size. 



B. Upper view of entire mandible. T V nat. size. 



C. Upper view of third right lower molar, g- nat. size. 



alv.j alveolus of tusk ; cond., condyle ; cor., coronoid process ; 

 m 3 j third lower molars. 



elongated anterior part (fig. 15), so striking in the last type, has 

 become shortened till it projects but little in advance of the 



