622 



3814. The skull and horns of a male Musk Ox (Ovibos moschatus). Hunterian. 



3815. The skull and horns of a male Musk Ox (Ovibos moschatus). Hunterian. 



3816. A mutilated skull and horns of a male Musk Ox (Ovibos moschatus). 



From the Polar regions of North America. 



Presented by Captain Sir Edward Parry, R.N. 



3817. The mutilated skull and horns of a female Musk Ox (Ovibos moschatus). 



Presented by Captain Sir Edward Parry, R.N. 



Genus Bison. 



3818. The skull of the male Aurochs (Bison europteus). 



In this genus the horns arise in advance of the superoccipital ridge which is formed by the 

 superoccipital bone, the parietals advancing to the upper surface of the skull and being inter- 

 posed between the frontal and superoccipital. The Bison differs from the Buffalo (Bubalus, 

 No. 3849) in the greater breadth and convexity of the frontal, and in the much greater extent 

 of the orbital processes of that bone, which, with the coextensive processes of the lacrymal 

 and malar, form a prominent cylinder of bone. The nasals are relatively shorter and broader 

 than in the Ox (Bos, No. 3828) ; but the chief distinction between the Bison and the Ox is 

 seen in its shorter premaxillaries, which do not rise to join the nasals : here, therefore, six 

 bones enter into the formation of the external nasal aperture, instead of four as in Bos and 

 Bubalus. The horns in the present species of Bison have a subcircular transverse section, 

 and curve outwards, upwards, and a little backwards. 



From Lithuania. 



Presented by Prof . Otto, of Breslau. 



3819. The bones of the trunk of a young male Aurochs (Bison europ&us). 



The vertebral formula is : 7 cervical, 14 dorsal, 5 lumbar, 4 sacral, and 17 caudal. Eight 

 ribs directly join the sternum, which consists of seven bones and a xiphoid cartilage. The 

 dentata has a broader and shorter spine than in the Common Ox ; that of the third cervical 

 is vertical, indicating the centre of the movements of the neck. The spine of the seventh 

 cervical is longer and more slender than in the Ox, and this difference is still more marked in 

 the spines of the anterior dorsal vertebrae. The spinal nerves directly perforate the neurapo- 

 physes of the third to the thirteenth dorsal vertebrae inclusive. From the fourth to the sixth 

 inclusive the outlet is crossed by a bony bar, extending from the diapophysis to the posterior 

 surface for articulating with the head of the rib. The ribs are more slender than in the Com- 

 mon Ox. The metapophysis is most distinct on the ninth, tenth and eleventh dorsals ; in 

 the thirteenth and fourteenth it has ascended to the zygapophysis. The change of form of 



