1900.] STRUCTURE OF THE MUSK-OX. 715 



animal and the Bovina. But, on the other hand, Ouibos must 

 have sprung from a form which was capable of developing: 

 accessory (basal) tubercles ; and that such tubercles are to be regarded 

 as the origin of the accessory columns also in Ouibos is proved by 

 the fact that sometimes these elements remain in a more primitive 

 stage as free independent pillars of cylindrical shape occupying the 

 place of the accessory columns. This is the case in both upper 

 molars of the hindmost pair in an old bull. But as the ancestors 

 of Ouibos must be sought for among ruminants with accessory 

 elements on the molars, these progenitors of the Musk-ox could 

 not have been Sheep, because the latter have specialized their 

 teeth without retaining; any of. the accessory columns of the 

 Musk-ox elements. Neither could it be assumed that the 

 accessory columns of the Musk-ox have originated independently 

 in this animal. 



The result of the above discussion may be stated thus : the 

 dentition of the Musk-ox as well as the other characteristics of 

 the skull do not indicate any Ovine affinities, but point to a com- 

 paratively primitive origin from which Ovibos has been specialized 

 in its own peculiar manner. It deserves consequently to maintain 

 its position in a separate subfamily. 



Sect. 4. — Comparison between the Skull of the Musk-ox 



AND THAT OF BuDOECAS. 



Through the kindness of Greheimrath Dr. Mobius I received 

 permission to borrow a skull of Badorcas from the Zoological 

 Museum of Berlin. I regret to say that the specimen sent to me 

 had been so badly damaged, that a comparison cannot be made 

 except with the facial portion of the skull. 



The nasals olBadyrcas are much more curved, trans versally as well 

 as longitudinally, than those of Ovibos, and their outline is also quite 

 different. Their greatest breadth, not quite a third of the length, 

 is at a point a little behind the middle. They are expanded 

 laterally in an obtuse angle so that each bone becomes triangular 

 in outline. In Ovibos the greatest width of the nasals is at their 

 posterior end, and their lateral border is a straight line. The 

 greatest width of the nasals is about a fourth of the length, more 

 or less, in the Musk-bull, in the Musk-cow not even that. The 

 nasals of Budorvas are pointed anteriorly without any lateral 

 notch, which is more or less conspicuous in the more blunt nasals 

 of an adult Ovibos, although it is small in a cow. The great 

 distance between the end of the nasals and intermaxillaries in 

 Badorcas, which is greater than the length of the nasals, indicates 

 a much greater development of the soft parts of the nose than in 

 the Musk-ox. The shape of the nasals of Budorcas can therefore 

 be derived from that of a more general form like Nemorhcedus 

 on the assumption that they have been shortened, as is always the 

 case when the nose attains a more or less trunk-like development. 

 As a result of such a development, the intermaxillaries are very 



