100 



COMPARATIVE OSTEOLOGY. 



to the shape of the horns, which they support. These are the flints or horn 

 cores, which are porous in their structure, especially at the roots ; they are very 

 rough, covered by thick periosteum, and contain sinuses, large canals, and 

 foramina, through which pass arteries and veins, and which are continuous 

 with the largely-developed frontal sinuses ; the latter extend from the orbit 

 to the extremities of the cores, and nearly as far backwards and downwards 

 as the foramen magnum. The superior surface of the frontal bone is flat and 

 broad, especially in the male. The supraorbital foramina are double, placed 

 very far backwards, and continued by a groove which extends backwards and 

 forwards. The frontal arch articulates with the malar portion of the zygoma. 



FIG. 26. 



SKULL OF AN Ox. Superior Aspect, 

 a, Frontal crest ; 6, Lateral crest ; c c c, Horn core , 

 d, Nasal peak ; e, Snpraorbital foramina: BONES : 

 1. Frontal ; 2. Lachrymal ; 3. Malar ; 4. Superior maxil- 

 lary ; 5. Nasal ; 6. Premaxilla, with Incisive-openings. 



The parietal bone is transversely elongated, and recurved at its extremities. 

 It is placed below the frontal crest, extending under and supporting the cores, 

 and entering the temporal fossa to articulate with the sphenoid and temporal 

 bones. Beneath the crest posteriorly it forms with its fellow the inter-parietal 

 suture. 



The Wormian bone exists, fused with the occipital and parietals. It is 

 described as " wanting," by some authorities. 



The occipital bone is not visible when the skull is viewed superiorly, being 

 concealed by the prominent frontal crest. It is much wider from side to side, 

 but smaller than in the horse. It has neither crest nor tuberosity, the condyles 

 being less prominent, but wider : the styloid processes are shorter, but broader, 

 and curved inwards. The basilar process is short and thick, with a large 

 basilar groove, and two rough prominences for muscular attachment anteriorly. 

 The condyloid foramina are double, sometimes triple. 



