oscoop] SCAPHOCEROS TYRRELLI 177 
tions, without regard to size, are very different. The entire molar 
and premolar series is much wider relative to its length than in 
Ovibos or Ovis, in this respect being like Bison. The width of m1 
is almost as great as the length and that of the much worn n2 
is even greater than the length, though it is possible that the unworn 
crowns might not show the same proportions. However, the alveolus 
of m1 is much wider than long. The longest tooth is m2, which is 
more than a third longer than m2, whereas in Ovibos these teeth 
are nearly equal in length. 
The arrangement of enamel folds seems to be much the same 
as in Ovibos but this is open to question since specimens of exactly 
equal stages of wear are not available for comparison. The greater 
width of the teeth naturally allows space for a greater proportion 
of dentine. With the exception of m2, all the teeth seem to be less 
prolonged into a posterior loop. In Ovibos this posterior loop fits 
into a corresponding depression in the front of the next succeeding 
tooth. In Scaphoceros, where the posterior loop is scarcely or not at 
all developed, the corresponding depression is absent. 
The accessory inner columns which are so well developed in Bos 
and Bison are not shown in the aged and worn teeth of the type 
of Scaphoceros. Since they occur in young Ovibos,’ they may well 
be expected in Scaphoceros when young specimens are found. 
Relationship —tIn its important characters, Scaphoceros appears 
to be more closely related to Ovibos than to any other recent genus. 
In its departures from Ovibos, it shows possible approach to Bison; 
on the other hand there is nothing indicating any further ovine char- 
acters than those that are claimed for Ovibos. The bearing of this 
upon the much discussed question as to whether Ovibos is more 
bovine or ovine in its relationships is rather favorable to the former. 
Without attempting to review all the moot points of this case, it may 
*The positive occurrence of these accessory columns in Ovibos has been 
noted by Rutimeyer (Die Rinder der Tertiar-Epoche, p. 91, 1867—fide Lonn- 
berg) and later by Loénnberg (Proc. Zool. Soc. Lond., p. 712, June, 1900), 
but seems to have attracted little attention, since the statement that they are 
absent in this genus is often seen. A young skull (No. 2924 U. S. Nat. 
Mus.) of Ovibos moschatus from Fort Good Hope, Mackenzie River, shows 
the accessory column plainly. In this skull m2 is only partly developed, 
being scarcely above the alveolar border; so far as can be observed under 
these conditions, the accessory column is not present in this tooth. In m2 
which is advanced enough to have been functional, the column is well devel- 
oped and conspicuous. It is a thin column occupying the single inner re- 
entrant angle and apparently derived from the inner anterior fold of the 
tooth. In m/ there is a trace of the same structure partly worn away, show- 
ing that continued wear would have caused it to disappear entirely. 
