SKELETON. 



533 



The first or mandibular arch is believed by many to form 

 Meckel's cartilage beneath, and the palato-pterygo-quadrate 

 cartilage above. Meckel's cartilage becomes the foundation 

 of the lower jaw, and bears a large tooth-bearing membrane 

 bone the dentary, a small corner bone the angular, while 

 the articular element is a cartilage bone. Of the bones 

 associated with the upper part, the palatine lies in front, the 

 quadrate articulates with the lower jaw ; while between 



FIG. 261. Pectoral girdle and fin of cod. From Edinburgh 

 Museum of Science and Art. 



/)., Fin-rays; l>.o., brachial ossicles; cor., coracoid ; sc., scapula; 

 cl., clavicle ; p.cl., post-clavicle ; s.cl., supra-clavicle ; /.A, post- 

 temporal. 



palatine and quadrate lie the pterygoid, the mesopterygoid, 

 and the metapterygoid. 



The second or hyoid arch is believed by many to form 

 the hyomandibular and the symplectic above, and various 

 hyoid bones beneath. The hyomandibular, and its inferior 

 segment the symplectic, connect the quadrate with the side 

 of the skull. Of the six hyal bones, the largest and most 

 important is the ceratohyal, which bears seven long branchio- 

 stegal rays. It is important to note that the bones formed 



