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12 



THE AMEEICAN BISOIsTS. 



would just about equal in length and thickness the average size of the horn- 

 cores of the adult male of either the aurochs or the American bison. 



Several teeth that apparently belong to this species have been described 

 by Dr. Leidy, together with some that represent a smaller species. The five 

 molar teeth from Natchez^ Mississippi, found in association with the remains 

 of Mastodon^ Eqims.^ Ursiis^ Cervus^ Megalonyx^ and Mylodon^ are the largest teeth 

 belonging to any known species of Bison^ being considerably larger than those 

 of Bison prisciis described by H. von Meyer^ from Mannheim^ Gei'many, as 

 well as much larger than those from California^ which are referable to the 



r 

 I 



species next described in the present paper. The specimens from Natchez 

 Dr. Leidy thus describes: ^^In the upper molars the external side exhibits six 

 folds, relatively not more prominent than in the common ox. Internally, 

 between the principal lobes, the accessory column is very well developed and 

 robust. The crescentic enamel pits or islands of the grinding 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 

 [a difference common to all the members of the bison group, as compared 

 with the repi-esentatives of the restricted genus Bos~\, The last lower molar 

 also presents a well-developed accessory column between the anterior pair of 

 the principal lobes externally, and in the worn-down specimen, upon the trit- 

 urating surface forms a correspondingly larger fold. In the unworn speci- 

 men the simimit of the posterior lobe bifurcates anteriorly, one portion 

 joining the postero-internal fold of the middle lobe, the other the postero- 

 external angle of the same lobe." 



These are the only teeth thus far described that seem to me to be referable 

 to the Bison Icdifrons, Those described by Dr. Leidy, from California,* evi- 

 dently belong to the smaller western form {Bison antiquus)^ of which Dr. 

 Leidy has also figured and described the skull. The tooth from Pittston 

 Luzerne County, Pennsylvania,! found with remains of Mastodon americamts 

 and Eqims major^ seems to wholly lack the accessory column, judging from the 

 figure, "the oval islet" being apparently not formed by the wearing down of 

 the accessory column. In other respects the tooth also resembles the corre- 

 sponding tooth of OviboSy and it seems to me is undoubtedly referable to the 

 extinct musk-ox and not to any form of Bison, It is in any case too small 

 for a tooth of Bison Mifrons, 



^^ 



7 



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^ 



* Ext Vert. Fauna, etc-, p- 254^ pi. xxviii^ figs* 6, 7. 

 f Ibid.j p. 255j pL xxviii, fig. 8. 



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