PLATE VI. 
Skulls of Bison americanus, males, showing the great diversity of form that obtains in adult individuals 
of the same sex. (One fourth natural size.) 
Fig. 1. View in profile of the skull of an old male from the plains of Kansas (specimen No. 1215). 
Fig. 2. View in profile of the skull of a male five or six years old from Kansas (spec. No. 94), 
Fig. 3. View in profile of the skull of an old male from Big-Bone Lick, Kentucky (spec. No, 2047). 
Fig. 4. View in profile of the skull of a middle-aged male from Big-Bone Lick, Kentucky (spec. 
No. 2050). 
Fig. 5. View in profile of the skull of a male about six years old from Kansas (spec. No. 108). 
Fig. 6. View in profile of the skull of an old male from Kansas (spec. No. 10). 
Fig. 7. View in profile of the skull of a male about six years old from Kansas (spec. No. 11). 
Fig. 8. View in profile of the skull of a male four or five years old from Kansas (spec. No. 100). 
