42 THE DISEASES AND DISOEDERS OP THE OX. 



the frontal sinuses are not prolonged beyond its superior 

 border. 



The parietal bone in the ox does not occupy the anterior 

 aspect of the head ; but it joins with the occipital bone in forming 

 the base of the neck. The parietal bone is a narrow osseous 

 plate elongated transversely, and recurved at its two extremities, 

 and it descends into the temporal fossa to rest upon the sphenoid 

 bone, and articulate with the sphenoid and temporal bones. The 

 parietal bones are small. Each is situated below the frontal crest, 

 and extends under and supports the horn cores. Beneath the 

 crest posteriorly the two parietals unite by means of the inter- 

 parietal suture; but there is never a central suture in ruminants. 

 There are no parietal ridges. The parietal bone of the ox is not 

 involved in the formation of the parieto-temporal canal, and it is 

 excavated internally by cavities which communicate with the 

 frontal sinuses. The parietal bone of the sheep and goat is rela- 

 tively much larger than that of the ox, and in these animals it 

 takes part in the formation of the parieto-temporal canal, and 

 has no sinuses. 



The occipital bone is much wider from side to side, but at the 

 same time smaller, than the occipital bone of the horse. The 

 occipital protuberance is obtuse, and gives rise to the superior 

 curved lines on each side. In the case of the occipital bone of 

 the sheep these curved lines are very marked, and they occupy 

 the summit of the head. The basilar process is wide, short, and 

 thick. The condyloid foramina are double and sometimes triple. 

 The foramen lacerum is divided into an anterior foramen and a 

 posterior one by means of the mastoid portion of the temporal 

 bone. In the sheep the basi-occipital is square and flat, but 

 it is longer in other groups. 



The Ethmoid Bone. — In ruminants the ethmoid bone and 

 its cells are well developed, and the great ethmoidal cell is of 

 enormous size. The ethmoid bone has a large volute prolonged 

 forwards, and it looks like a third turbinated bone prolonged 

 between the two turbinated bones usually met with. It has been 

 called the olfactory antrum or cave. The ethmoid bone is closely 

 fixed between the adjacent bones, in consequence of the slight 

 development of the sinuses around it. 



The Sphenoid Bone. — In the ox the pterygoid processes are 

 large and thin. The sub-sphenoidal canal is not present. The 



