oscoop] SCAPHOCEROS TYRRELLI ~ 181 
maximus is of corresponding dimensions.’ If this be the case I 
would ask, as the ‘ dentata of maximus’ was found in the country 
of ‘ the musk-bull,’ and is of the same size as the corresponding bone 
in that animal, what evidence is there that it does not belong to it?’ 
The dentata described as O. maximus may represent the same 
species as the one here described as tyrrelli, but there seems to be 
no material now available by which this can be determined. At least 
it is certain that the dentata shows no generic characters. As it is 
necessary to have a species for the type of a genus, the only speci- 
men which shows generic characters should be taken as the type 
of both species and genus. By so doing, the genus becomes estab- 
lished and will not be affected should later developments prove that 
the type species is a synonym. 
7. Ovibos priscus is a substitute name for both B. bombifrons 
and O. cavifrons, which by some esoteric method of reasoning was 
supposed to be necessary, when it was assumed that cavifrons repre- 
sented the male and bombifrons the female of one species. 
8. Bison appalachicolus was based on a rather small fragment of 
the base of a horn. It was at first placed in the genus Bison, and 
considered as an intermediate form between Bison and Ovibos. 
Later it was transferred to the genus Ovibos by the same author.’ 
The Genus Bootherium.—Bootherium, when originally proposed 
by Leidy® included two species, Bos bombifrons Harlan and Ovibos 
cavifrons Leidy. Since that time neither of these has been removed 
as the type of a new genus. [If it is now concluded that these species 
are not congeneric, one of them must be designated or fixed as the 
type of Boétherium. I have therefore selected Bos bombifrons 
Harlan as the type of. Bodtherium and referred O. cavifrons Leidy 
to the new genus Scaphoceros, of which the type is S. tyrrelli. As 
justifying this fixing of the type, it may be said that at the time 
Bootherium was proposed, Bos bombifrons had been thoroughly 
described and figured, whereas O. cavifrons had received only slight 
preliminary mention. Moreover B. bombifrons was the species first 
mentioned in the paper in which Bodtherium was first published. 
Since bombifrons and cavifrons have been considered by several 
authors as being not only congeneric but conspecific, the establish- 
ment of a separate genus for each may appear surprising. While it 
may be possible, from examination of figures only, to construct a 
hypothesis to the effect that cavifrons represents the male and bombi- 
*Proc. Acad. Nat. Sci. Phila., pp. 209-210, 1854. 
2 Proc. Acad. Nat. Sci. Phila., p. 492 (1897), Jan. 18, 1808. 
8’ Proc. Acad. Nat. Sci. Phila., p. 71, 1852. 
