620 PHYLUM CHORDATA I CLASS PISCES— FISHES 



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

 mandibular and the syraplectic 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 





Ft. „^<s'?.«> 



Fig. 355. — Disarticulated skull of cod. 



S.O., Supra-occipital ; Pa., parietal ; Fr., frontal ; M.E., meseth- 

 moid ; N., nasal ; P.E., parethmoid ; Ot., otics ; E.O., ex-occi- 

 pital ; B.O., basi-occipital ; Pa.S., parasphenoid ; V., vomer ; 

 L., lachrymal ; orb., orbitals ; H.M., hyomandibular ; S., 

 symplectic ; Q., quadrate ; PL, pterygoid ; mt.pt., metaptery- 

 goid ; ms.pt., mesopterygoid ; PL, palatine ; Mx., maxilla ; 

 Pmy., premaxilla ; Ar., articular; An., angular; D., dentary ; 

 u.h., urohyal ; h.h., hypohyal ; c.h., ceratohyal ; ep.h., epihyal ; 

 Lh., interhyal ; Op., opercular ; S.op., sub-opercular ; t.op., 

 inter-opercular ; p.op., pre -opercular. 



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 

 membrane bones. 



