THE AMERICAN BISONS. 35 



mammalia, but it may have survived to a comparatively recent date. There 

 is nothing to indicate whether it was or was not contemporaneous with the 

 larger extinct bison, except that the remains of both species occur with those 

 of the same species of other extinct mammals. Judging by the same evi- 

 dence, both may also have been contemporaneous with the Bison prisma of 

 the Old World. 



5. — Relation of the Existing Species of Bisons to the 

 Extlnct Species. 



European writers seem to have fallen into rather confused and erroneous 

 notions respecting the affinities of the different forms of living and extinct 

 bisons. By the earlier writers all the remains of extinct bisons were re- 

 ferred to the aurochs, which was considered as the modern degenerate race 

 of the older form. Later the extinct bisons were viewed as a species dis- 

 tinct from the living, but all of the extinct ones were referred to the 

 same species. Quite recently Rutimeyer, while maintaining this view re- 

 specting the fossil forms,* has considered the Bison americanus as the older 

 form, through which Bison bonasus has passed in reaching its present estate. 

 This conclusion, based on developmental features of the teeth and skull, has 

 been accepted by Brandt and other writers on the subject, contrary, it 

 appears to me, to the teaching of general facts. Lilljeborg has even car- 

 ried his generalization to the absurd extreme of referring all the forms of 

 Bison to the Bos bonasus of Linne ! 



The evidence bearing upon the question of the actual geological sequence 

 of the different extinct forms is by no means decisive or satisfactory. If we 

 regard, however, the gigantic B. latifrons, with its immense horns spreading 

 ten to twelve feet, as the older type, passing into, on the one hand, the 

 Bison prisons of the Old World, and on the other, into the Bison antiquus of 

 the New World, the former giving origin to the existing Bmn bonasus and 

 the latter to the existing Bison americanus, we have what seems to be a 

 natural transition throughout the series. Both in the Old World and the 

 New, the older form is larger than the more recent, with disproportionately 



* Strangely and against all analogy, Rutimeyer regards the small Bison antiquus of Leidy as the male 

 and the gigantic Bison latifrons as the female, of one and the same species, and both as identical -with the 

 Old World extinct bison. 



