XIII. J THE FEOG. 211 



c. The under jaw or mandible consists of two distinct 

 portions, or rami, which meet in the middle line 

 in front, and which, behind, articulate with the 

 extremities of the suspensorial cartilages. In the 

 articular end of each suspensorial cartilage there 

 is an ossification which represents the quadrate 

 bone in other Vertebrata, and- is united with the 

 jugal to form the quadrato-jugal. 



In each ramus three pieces may be made out — 



a. A central axis formed of cartilage {Meckel's 

 cartilage), which enlarges at its posterior end 

 in order to articulate with the suspensorial 

 cartilage, while at the opposite or symphysial 

 end it is ossified to form the mento-Meckelian 

 bone. 



/3. A posterior inferior piece, which runs nearly to 

 the middle line in front {angulo-splenial) and 

 partly ensheaths the foregoing. 



7. A small anterior superior piece {dentary). 



d. The hyoid bone or cartilage. 



a. Its broad somewhat tetragonal central part 

 {body), bearing a number of processes, viz. — 



/8. The anterior cornua, proceeding from the front 

 of the body on each side : each is a long 

 slender curved cartilage running at first for- 

 wards, then backwards and outwards, and 

 finally forwards and upwards, to become at- 

 tached to the periotic capsule beneath the 

 fenestra ovalis. 



14;— 2 



