THE AMERICAN BISONS. 23 
also sufficiently resembles the fossil from Eschscholtz Bay, described by 
Buckland and Richardson, and referred by the latter to an extinct species, 
with the name Dison crassicorms, to render it probable that this may have 
belonged to the same species”;* and in his table of synonymy published at 
this time he refers both B. antiquus and B. erassicornis to B. latifrons. 
Respecting the California specimen, in a fuller account of it published 
later, with figures,t Dr. Leidy also says: “The specimen resembles the cor- 
responding part of the skull of the living buffalo (Dison americanus) so closely 
that it will be unnecessary to describe it in detail. Besides being larger, 
the horn-cores are especially disproportionately larger, and are more trans- 
verse in their direction, or are less inclined backward. The occiput appears 
proportionately wider and lower from the less degree of prominence of its 
summit. The latter is, however, wider, and is more distinctly defined from 
the posterior occipital surface by the rougher and more prominent protu- 
berance of attachment for the nuchal ligament. The occipital foramen is 
no larger than in the buffalo, and the notch below, between the condyles, 
is more contracted. The forehead, near its middle, is rather more protuber- 
ant than in the buffalo.” At this time he very properly deemed the material 
insufficient to determine whether the remains from this continent of “large 
oxen which were contemporaneous with the American mastodon,” and which 
had been referred to several distinct species, really pertain to more than one. 
He, however, still inclined to the opinion of the specific unity of all the 
forms; “the more robust specimens,” he says again, “ probably belonged to 
males, and the smaller ones to females.” t 
This view, however, as already stated, seems to me untenable, the fossil 
bison remains thus far known apparently indicating two quite.distinct extinct 
species of bison in North America, the larger very much exceeding in size, 
and doubtless otherwise differing from Bison priscus of Europe and Asia, and 
the other of about the size of Bison priscus, but differing from it in important 
features, and closely resembling in many points the bisons still existing. 
The Bison crassicorms of Richardson was based on “ the fragment of a skull 
brought home by Captain Beechey, and figured by Dr. Buckland in pl. iii, 
fig. 1,”§ and “referred by him [Beechey] to Bos urus, by which is meant,’ 
* Ext. Mam. of North America, p. 373, 1869. 
t Ext. Vert. Faun., p. 253, pl. xxviii, figs. 4, 5, 1873. 
t Ibid, p. 253. 
§ Beechey’s Voyage to the Pacific, Vol. IL. 
