8 PLEISTOCENE MAMMALIA. 



Teellt. — The ovine and caprine affinities visible in the skull of the ]\Iusk Sheep are- 

 visible also in the teeth ; the upper true molars are diiferentiated from those of Bison and 

 Buffalo by the shai'pness, stoutness, and prominence of the three principal costse on their 

 outer surface, and the small development of the two secondary ones. The crowns also of 

 the teeth are not so broad. On the internal aspect there is no accessory column, a point which 

 would at once separate them from Bos, Bubalus, and Bison. There is a small accessory valley 

 at the inner interspace between the two principal ones, which is present also in Bos Caffer. It 

 is absent from many of the Oxen, and is in the Musk Sheep invariably larger and deeper than 

 in any of the true Bovidae. A strong process passes from the inner side of the valley in 

 premolar, and diagonally backwards as far as its external border. The anterior edge of the 

 first premolar (P. M. 2) is much sharper than in any of the Bovidge, and differs in th& 

 simplicity of its crown from that of Bubalus Caffer. The low^er jaw teeth differ from those 

 of Oxen in the length of the anterior costa, and by its being continued past the cingulum, . 

 by the fusion of the posterior valley in molar 3 with the second, and by the narrowness of 

 the teeth. In premolars 4 and 3, also, the posterior lobe is much more clearly defined. 

 In other respects the lower dentition is closely allied to that of the domestic Ox. The form 

 of the lower jaw is essentially ovine or caprine, differing from those of Ox and Bison in 

 the proportions which are given in the measm'ements. 



§ 2. VertehrcR. — The vertebrae have been described and figui'ed so admirably by Sir 

 John Richardson in the ' Zoology of the Herald,' pp. 72 — 89, that all that is necessary 

 to be said about them here is, that their zoological evidence agrees with that of the rest of 

 the skeleton. They consist of seven cervicals, thirteen dorsals, six lumbars, six sacrals, and 

 six caudals. 



Scapula. — The scapula, in common with that of Ovis, differs from that of Ox in the 

 straightness of its spine, in the curvature of the dorsal edge, and the small size of the 

 crown. 



Humerus. — The humeruspresents the followingovine characteristics : — The deltoidridge 

 is smaller and less everted, the superior tuberosity is more massive, and the ridge running 

 from the deltoid to the outer side of the proximal articulation is less marked than in the 

 corresponding Ox bone ; the bone itself is also more slender. 



Radius. — The radius presents the following differences from that of Bos : — The tube- 

 rosity on the exterior of the proximal end is further removed from the articulation, and the 

 bone itself is smoother and rounder, the muscular impressions are not so strongly marked. 



TJlna. — The superior surface of the olecranon is rounded; and is much shorter than in 

 Bos or Bison, in which it ends in a sharp ridge ; the transverse diameter of the proximal 

 articulation is also greater ; the groove at the point of anchylosis with the radius is also 

 absent ; all these are ovine and caprine characters. 



Metacarpal. — The metacarpal is shorter and stouter than that of Ox, its dorsal surface 

 bears the merest trace of an extensor groove ; the synovial cavity between the articulations- 



