from a foramen into the orbit and passes forward next 

 to the membranous septum. Anteriorly it passes laterally 

 between the inferior and superior oblique muscles to reach 

 the olfactory foramen in the olfactory capsule. The olfactory 

 capsules become separated by the midline rostral chamber 

 opening into the orbits at either side of the interorbital 

 septum — this chamber is the anterior myodome. 



loterol ethmoid parietal 

 mesethmoid 

 nasal 



The posterior myodome (Figure 5-7) is formed by the 

 rectus eye muscles "pushing" their area of origin (attach- 

 ment) down through the hypophyseal fenestra and then 

 back below the level of the trabeculae on to the basis 

 cranii. The posterior parts of the trabeculae degenerate, 

 and a new pseudohypophyseal fenestra, the sellar fenestra, 

 is formed by ossificadon in the connective tissue septum 



suprooccipitol 



lateral rostral. 



maxilla 



extrascapular series . ■ .. 



^ autopalatine 



'ntercalare ^i j 



mesethmoid 

 hyomandibulo 



palotri 



interopercle 

 uadrate 

 branchiostegal ray 



lateral ethmoid 

 subopercle 



ectopterygoid 



symplectic parietal 



, sphenotic 



preopercle 



postparietal 

 suprotemporotabular. 



intercalare 



suprooccipitol 



palatine 



pterygoid 

 ectopterygoid 

 quadrate 



symplectic 

 metopterygoid 



prootic 

 hyomandibulo 



pterotic attached to 

 suprotemporotabular 



hyomandibulo 

 metopterygoid (epipterygoid) 



ectopterygoid. 



preopercle 



hypohyol 



ntercalare 



interhyal 



subopercle 

 interopercle 

 cerotohyol posterior 



cerotohyal anterior 



Figure 5-3. Head skeleton of the cod. A, lateral view; B, dorsal view of the skull with nasal and 

 circumorbitols of left side removed; C, ventral view of skull with palatoquadrate complex and 

 hyomandibulo of right side (to left) removed; D, medial view of suspensorium of right side. 



GNATHOSTOME FISHES 



109 



