60 



SINCLAIR— THE SMALL ENTELODONTS 



E, F), and also a variation in the size of the metaconule (Fig. 3 

 C-F). Lower jaws are associated with some of the skulls showing 

 these types of third molar and in' them variations in the spacing of 

 the anterior premolars and in the structure of the lower molar heels 



A 



B 



■fi^ 



yni. 



IZt>Z'^._ 



//4^0 



c* 



/4?- 



¥. 



Fig. 4. Archaotherium mortoni, lower dentition of the right side crown 

 view, one half of the natural size. A. Lower jaw of large skull from Bear 

 Creek, showing the empty alveoles of the anterior teeth, m and m alone 

 remaining in place. B. Lower dentition with well-spaced premolars belong- 

 ing with a small skull from Sand Creek, Nebraska. Both specimens in the 

 Princeton collection. 



