270 ZOOTOMY. 



In the adult, the basi-, ex-, and supraoccipitals are all 

 fused together into the single occipital bone. 



45. The interparietal, a small transversely oval bone, 

 interposed between the middle part of the front edge of the 

 supraoccipital and the parietals ( 46). 



46. The parietals, a pair of thin, slightly arched bones, 

 forming a considerable part of the roof of the brain-case : 

 they are separated from one another by the median sagittal 

 suture, and from the interparietal and supraoccipital, with 

 which they articulate posteriorly, by the transverse lamb- 

 doidal suture : the outer edge of each gives off a long 

 downwardly directed process, which, in the entire skull, is 

 covered by the squamosal ( 53). 



47. The frontals, roofing in the anterior part of the 

 brain-case, articulated with one another in the middle line 

 by the frontal suture, and with the parietals behind by 

 the transverse coronal suture. Each is an irregular bone, 

 with a slightly arched upper surface ; an irregular anterior 

 border ; an orbital process, a thin plate continued down- 

 wards and inwards from its outer border, and forming the 

 upper part of the inner wall of the orbit; and a supra- 

 orbital process, projecting directly outwards from the 

 outer border, free at both ends, and forming a protection to 

 the orbit above. 



48. The basisphenoid, articulated behind by a broad 

 surface with the basioccipital, and tapering in front to a 

 blunt point; it is perforated at about the middle of its 

 extent by an oval foramen, and its upper surface is hollowed 

 out to form the sella turcica, which lodges the pituitary 

 body ( 484), and is bounded before and behind by the 

 anterior and posterior clinoid processes, of which 

 the latter only are formed by the basisphenoid. 



49. The alisphenoids : two wing-like bones directed 



