700 DE. E. LONNBERG ON THE [June 19, 



type is improbable, at least as long as the armature — the horns — 

 which have been the cause of the development, are retained. But 

 there is no difficulty in assuming that from the same indifferent 

 type have been developed forms which have specialized their 

 armature differently, the one as Ovibos mosehatus and the other as 

 " Bootherium " or Ovibos bombifrons ; and that in such a case the 

 latter has acquired a characteristic, the frontal elevation, which 

 offers some resemblance to the ovine type. But then this is only 

 a parallel, and proves no affinity with the ovine type. There seems 

 also no need for assuming Bootherium as being older than Ovibos, 

 as both have occurred in the Pleistocene \ 



In a young calf of Ovibos, the length of the parietals near the 

 median line is 40 per cent, of the length of the frontals measured 

 in the median line. This relation, however, diminishes with age, 

 so that in an old bull the corresponding percentage is 30-35. It 

 is, however, a little difficult to perceive the sutures at the surface 

 between the frontals and the parietals, but the sutura lambdoidea is 

 distinguishable, although nearly obliterated, even in the oldest 

 skull I have seen. The parietal zone on the top of the head is 

 thus already in the calf, compared with the frontal region, shorter 

 than in many Antelopes (Gazella, Cephalophus, Nemorlicedus, Rujji- 

 capra, &c). In the Sheep and the Goats the relation varies a 

 good deal, but in many cases the parietal zone is not even 30 per 

 cent, of the frontal, and is accordingly more reduced than in the 

 Musk-ox. The latter seems thus, with regard to the development 

 of the parietal region, to occupy an intermediate position between 

 the Sheep and the more primitive Antelopes. 



On the sides, the parietals of the Musk-ox extend with a rather 

 short and truncate portion forward between the frontal and 

 squamosal. The anterior end of this portion reaches only half- 

 way between the orbit and a vertical line drawn through the 

 meatus auditorius externus. This shortness of the lateral portion 

 of the parietal in the Musk-ox has the result that the frontal meets 

 the squamosal, and forms with it a rather long suture on the lateral 



1 I must confess, however, that I only know Bootherium from the figures 

 published by Boyd Dawkins (Pakeontograpbical Society, vol. xxv. Monogr. on 

 the Brit. Mamrn. of the Pleistocene, genus Ovibos, pi. v.), and from descriptions. 

 Fig. <3 on the plate quoted is said to be a coronal view of the skull of Bootherium 

 bombifrons Leidy, and is regarded by Dawkins as belonging to an adult female. 

 It is, however, rather similar to the aspect of the skull of a young Musk-ox, and 

 ought to be compared with Sir John Richardson's figure (Zoology of the 

 ' Herald,' pi. iv. fig. 2). Fig. 4 on Dawkins's plate is said to be a lateral view 

 of the same, which nevertheless is bardly possible, to judge from the general 

 appearance as well as from the dimensions. Dawkins's fig. 4 of Bootherium 

 cavifrons Leidy is regarded as belonging to an old male, which seems very 

 probable from comparison with the Musk-ox, in which the large exostoses at the 

 base of the horn-core get reabsorbed in old age. These forms may belong to 

 the same species, representing the female and the male form, as Riitimeyer and 

 Boyd Dawkins have suggested, but their ovine affinities I cannot see. Wben 

 Riitimeyer says (op. cit. p. 18) that the horns of Bootherium have been " ohne 

 Andeutung einer riickwarts Beugung der Spitzen," ii must be remembered that 

 the horn-cores of these animals are so short that they indicate only the direction 

 of the basal parts of the horns. 



