DAKOTA AND NEBRASKA. 193 



2. The crown of an inferior molar tooth, represented in figures 8, 9, plate XXVII, 

 and the greater portion of another specimen of larger size. Tlie comparative 

 measurements of the two specimens are as follow : 



Lines. Lines. 



Antero-posterior diameter, . . . . . .15 16 J 



Transverse diameter, . . . , . . . 12 14 



3. The greater portion of the crown of a third upper premolar, and the last lower 

 premolar which is represented in figure 11, plate XXVII. These teeth appear not 

 to have been protruded from the jaw, as they are not only unworn, but the crowns 

 are hollow, with thin walls. 



The upper premolar has the crown about sixteen lines long, has been about an inch 

 and a half wide at base, and in this position is three-fourths of an inch thick. The 

 lower premolar has the crown fourteen lines long at the middle externally, with 

 the base twenty lines wide, and ten lines thick just back of its middle. 



4. A portion of the upper jaw, containing on one side the fangs of the posterior two 

 premolars and the true molars, and on the opposite side those of the same premolars 

 and of the first true molar. The measurements of the specimen are as follow : 



Lines. 



Space occupied by the true molars, about . . . • .42 



Breadth of face above second true molars, . . . . .52 



Breadth of face at ant-orbital foramina, . . . . . .30 



Breadth of nasals at frontal angular processes, . . . .20 



5. Fragments of the upper jaw of a young animal. One contains the first premolar 

 unworn, in which condition the crown is seven lines long, nine broad, and five thick. 

 Another fragment contains the last temporary premolar, the temporary true molar, 

 and the first permanent true molar. The measurements of the teeth are as follow : 



Lines. 



Antero-posterior diameter of permanent true molar, . . .14 



Transverse " " " 



Antero-posterior diameter of temporary true molar, 



Transverse " " " 



Antero-posterior diameter of last temporary premolar. 



Transverse " " " 



14 

 12 

 11 

 13 



9 



Some additional specimens, apparently belonging to idotlierium ingens, obtained by 

 Dr. Hayden in the Mauvaises Terres in the summer of 1866, are as follow : 



The middle portion of the face, considerably mutilated and without any portion of 

 the lower jaw. It contains on one side the remains of the fangs of the true molars, 



25 



