PLATE IV. 



Fig. 1. Hyracodon priscidens, Lambe; left maxilla with premolar and molar teeth. Type. 



Page 39. 

 Fig. 2. The same specimen, outer aspect. 



Hyracodon priscidens, Lambe ; anterior end of mandible, outer view from the left. 



The same specimen, seen from above. 



Aceratherium mite, Cope ; left upper third molar, seen from below. Page 43. 



? Leptaceratherium trigonodon, Osb. and "Wort. ; right upper third molar, as seen 



from below. Page 44. 

 Aceratherium occidentale (Leidy) ; left lower third molar, view from above. Page 44. 



pr., protocone : d., deuterocone ; tr., tritocone ; te., tetartocone; c, canine ; Pa, second 

 premolar. 



Fig. 



3. 



Fig. 



4. 



Fig. 



5. 



Fig. 



6. 



Fig. 



7. 



