498 



FISHES. 



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. 



The toothed premaxilla forms the upper part of the gape, 



Er. 



p.op. 



FIG. 167. Disarticulated skull of Cod. (From Edinburgh 

 Museum of Science and Art. ) 



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

 moid; N., nasal; P.E., parethmoid ; Of., 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 ; Pt., pterygoid ; uit.pt., metapterygoid ; 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 ; ih., inter-hyal; Op.. 

 opercular ; S.op., sub-opercular ; i.op., inter-opercular ', p.op., prae- 

 opercular. 



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. 



In the opercular fold are four membrane bones. 



