554 



PISCES FISHES. 



The first or mandibnlar 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 palatine 

 and quadrate lie the pterygoid, the mesopterygoid, arid the meta- 

 pterygoid. 



The second or hyoid arch is believed by many to form the hyo- 



/ si', j 



CO T. b.O. 



FIG. 296. Pectoral girdle and fin of cod. 



/>-., Fin-rays; 6.0., brachial ossicles; cor., coracoid ; sc. , scapula ; 

 c/., clavicle ; p,cl.^ post-clavicle ; s.cl., supra-clavicle ; p.t.^ post- 

 temporal. 



mandibular 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 

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

 in connection with these arches do not yet form an integral part of the 

 skull. 



The toothed premaxilla forms the upper part of the gape, while the 

 maxilla which articulates dorsally with the vomer, and nearly reaches 

 the quadrate posteriorly, does not enter into the gape. Both are mem- 

 brane bones. 



