66 



Fore and aft. 



Lines 



Diameter of first premolar .'U 



Diameter of second premolar 4£ 



Diameter of third premolar 



Diameter of fourth premolar G£ 



Diameter of first molar 



Diameter of second molar 



Diameter of third molar 



I.I III ' . 



H 



H 



Si 



Transverse. 



Lines. 



2 



Line*. 



H 



4 

 5 



5 



Hyrachyus agrarius was about the size of the common collared peccary, 

 Dicotyles torquatus. 



HYRACHYUb EX1MIUS. 



A supposed larger species of Hyrachyus than H. agrarius is inferred from 

 several specimens, consisting of small fragments of a lower jaw with a tooth 

 and portions of others. These were obtained by Dr. Carter on Henry's Fork 

 of Green River. . 



The best and most characteristic specimen is represented in Figs. 19, 20, 

 Plate IV, consisting of a lower-jaw fragment containing the last premolar and 

 portion of the first molar much worn. Both the teeth and the jaw agree in 

 form with the corresponding parts in Hyrachyus agrarius and differ only in 

 size. The specimen also agrees with the corresponding part of Lophiodon 

 sufficiently to belong to the same genus, so that until more ample material is 

 discovered it must remain uncertain whether it really pertains to Hyrachyus. 



Comparative measurements are as follows : 



H. eximius. H. airraiius 



Depth of jaw at last premolar 



Thickness of jaw at last premolar 



Diameter fore and aft of last premolar . 

 Diameter transversely of last premolar. 



Diameter trausversly of first molar 



Diameter transversely of second molar. 



Lines. 



L 



ncs. 



IS 





m 



9 





7 



7 





5| 



5J 





4 



6£ 





5 



7 





5i 



Figs. 9, 10, Plate XXVI, represent a tooth recently obtained by Dr. Car- 

 ter on the buttes of Dry Creek. It would appear, from its proportions, to be 

 the left lower penultimate molar of Hyrachijus eximius. It is a nearly un- 



