196 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



Measurements of teeth of Bison latifrons. 



According to Leidy's figures, however, the second upper molar has 

 a fore-and-aft extent of 39 or 40 mm., and the hmder molar an extent 

 of 41 mm. The width of this last-mentioned tooth is that at the 

 bottom, where greatest. The width of the other two seems to have 

 been taken at the middle of the height of the tooth. Furthermore, it 

 is not certam that Leidy had the first true molar; hence that meas- 

 urement had better be disregarded. Otherwise, tlie two sets of teeth 

 are of practically the same size. 



Leidy stated that "the crescent Jc enamel pits or islands of the 

 gi-mding surface are more simple than in the ox, and appear relatively 

 more capacious as a result of their greater simplicity or less degree of 

 inversion of the sides of the pits." Figure 3 of his plate 2 shows well 

 the size of the islands or lakes and the simplicity of the enamel of their 

 walls. Leidy's figure, showing the grinding surface of the second 

 upper premolar, is here reproduced (pi. 19, fig. 2). An examination 

 of the lakes of Bison regius shows a different state of affairs. Here 

 the lakes have the sides, especially the outer one of each, and to a less 

 degree the inner one, pushed strongly toward the interior of the lake. 

 The result is to produce in each lake a pau* of narrow cornua project- 

 ing outwardly and a much contracted interior. There is another 

 feature which is less commonly seen in bisons. In the front border 

 of some of the lakes, or m the hmder border of others, or in both 

 of these, there is seen a sharp infolding of the enamel, which consider- 

 ably compHcates its arrangement. The wi'iter finds this complication 

 in none of several recent specimens of B. hison examined. In the 

 front wall of the posterior lake of the first upper molar of a set of 

 teeth figured by J. A. Allen, found at Big Bone Lick, Kentucky, and 

 referred to B. hison, we find an inflexion of the enamel, such as is 

 found in B. regius. In examining several specimens of Buhalus caffer, 

 the African buffalo, the writer finds in most of the lakes of the upper 

 molars similar infoldmgs of the enamel. The character appears, 

 therefore, to be of specific importance. It is possible that the large 

 teeth described by Leidy do not belong to B. latifrons; but if not, there 

 is probably indicated still another undescribed bison. It is, how- 

 ever, probable that they do belong there; and if so, B. latifrons and 

 B. regius, among American bisons, stand at the extremes of the com- 

 plication of the enamel in the walls of the cement lakes. 



