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PLATE IX. 



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of Bison americaaus. (All the figures natural size.) 



Fig. 1. Right lower pre-molars seen from above, from a very yoxmg individual (the first true molar is 



just in sight). Specimen No. 590. 

 Fig. 2. The same seen from the outside. 



Fig. 3. Eight upper pre-molars seen from above, from the same specimen. 

 Fig. 4. The same seen from the outside. 



Fig. 5. Right lower pre-molars, seen from above, from a somewhat older specimen, in which the first true 



molar is fully in sight. Specimen Ko. 1153. 

 Fig. 6. The same, seen from the outside. 



V ■ 



Fig. 7. Right upper pre-molars, seen from above, from a specimen of about the same age as No. ] 153. 

 Drawn from specimen No. 1155. 



Fig. 8. The same, seen from the outside. 



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