PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 63. 



lively, to B. bison, B. bison, B. dlleni, and B. bonasus. It will be 

 noted that there is close agreement among the first three skulls, 

 and again between the fifth and sixth ; and at the same time a good 

 deal of diiference between the two groups. The skull of the fourth 

 column agrees with the skulls of B. bison and not with those of B. 

 ocddentalis. On other grounds it had been concluded that this 

 skull belongs to B. bison. The horn-cores are those of B. bison, 

 as liVAy be seen in the measurements of Table 1. 



If measurements across the face be taken halfway between the 

 maxillomalar sutures and the rough eminence on the ridge, and these 

 be compared with the width at the rear of the orbits, the following 

 indices will be obtained: 



Here again it is found that the faces of the two specimens of 

 B. ocddentalis are relatively narrower than those of the two recent 

 bisons; also that number 10544 from Minnesota ranges itself with the 

 recent bisons. The European bison No. 11514 is shown in this table, 

 as in the preceding one, to have a face nearly as narrow, relatively 

 to the width at the rear of the orbit, as has B. occidentaUs. 



The distal end of the muzzle of B. occidentaUs (pi. 1, fig. 1) is not 

 cut off as squarely as it is in B. bison. Another character which 

 appears to distinguish B. occidentaUs from B. bison is found in the 

 premaxilla. This is much longer in the former (pi, 2, fig. 2) than in 

 the latter. In the former its length is equal to the distance from the 

 hinder end of the bone to the rear of the orbit or slightly in front. 

 In B. bison the length of the premaxilla reaches only to the front of 

 the orbit or a little beyond. As a result of this greater length of the 

 premaxilla in B. occidentaUs the free border of the maxilla in the 

 nasal opening is only about one-half as long as it is in B. bison. The 

 specimen from Minnesota having the catalogue number 10544 

 resembles in this respect the recent skulls of B. bison. 



The upper teeth of the two best skulls in the Minnesota collection 

 are nearly all badly injured (pi. 2, fig. 1). So far as preserved, they 

 appear to present no differences when compared with those of B. 

 bison. 



It is very difficult or impossible to find means for distinguishing 

 the teeth of any of our species of bison from those of the others. It 

 is somewhat surprising, therefore, to find that the teeth of B. bonasus 



