220 ELEMENTARY BIOLOGY. [CHAP. 



a. A central axis formed of cartilage (MeckeFs 

 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. 



/5. A posterior inferior piece, which runs nearly to 

 the middle line in front (angulo-splenial) and 

 partly ensheaths the foregoing. 



y. 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. 



(3. The anterior cornua, proceeding from the 

 front of the body on each side : each is a 

 long slender curved cartilage running at first 

 forwards, then backwards and outwards, and 

 finally forwards and upwards, to become at- 

 tached to the periotic capsule beneath the 

 fenestra ovalis. 



y. The posterior cornua, or thyro-hyals ; bony, 

 and shorter and thicker than the anterior 

 cornua: attached to the posterior border of 

 the body near the middle line and diverging 

 as they run backwards. 



B. Two pairs of smaller processes formed by the 

 elongation of the anterior and posterior an- 

 gles of the body of the hyoid. 



e. The sternum and shoulder-girdle. 



i. Their general arrangement : they form an incomplete 

 ring round the fore-part of the trunk : this ring is 



