THE SKULL. ZJ 



join its fellow in the middle line in front ; di- 

 vide the cartilage at this point, and remove 

 the whole loosened piece ; it consists of four 

 bones, which are to be separated and exam- 

 ined. 



c. One of these pieces, placed to the outside, and 

 forming the outer boundary of the fissure 

 above mentioned (53), is a thin bone, lying in 

 the vertical plane ; it is the surangular. In the 

 natural position of the parts it is largely over- 

 lapped by the dentary (54, h). 



d. Forming the inner boundary of the fissure, and 

 reaching back to form part of the surface which 

 articulates with the quadrate, is another thin, 

 flat bone, placed vertically : it is the splenial, 

 and forms nearly all the inner surface of the 

 ramus of the mandible. 



e. Wedged in between the lower edges of the 

 splenial and surangular is a narrow bony bar, 

 the OS angulare. 



f. When the above pieces are removed, Meckel's 

 cartilage will be left, with a small polygonal 

 bone continuous with its posterior end. This 

 bone is the os articulare. It forms most of the 

 articular facet of the mandible, and is the only 

 part of it ossified in cartilage. 



g. The part of the mandible left when the above 

 loosened portion (54, b) was removed, contains 

 two bones : one is the coronoid, which forms 

 the process of that name (53), and articulates 

 in front with — 



h. The dentary, which is anchylosed to its fellow 

 in the middle line in front, and also sends back 



