SKULL 



347 



be assumed that the condition in which the parietals meet in 

 the middle line and are not separated by the supraoccipital is 

 primitive ; it is found in the lower Teleostomes, where, indeed, 

 the supraoccipital has not yet appeared (p. 326). But, although it 

 is the rule in the lower sub-orders that the parietals meet, yet even 

 in the Clupeiformes there are genera in which the supraoccipital 

 touches the frontals underneath the parietals (Slops, Alhila, Chanos), 

 and among the Acanthopterygii the parietals may sometimes meet 



fr. 



t>f. 



so. 



n 



FIG. 32S. 



Left -side view of the skull of Gadus morrhna, L. The branches of the facial nerve 

 are shown, and the course of the lateral-line system (by a series of dots), partly after Cole. 

 an, angular ; art, articular ; 6, barbel ; b.c, buccal branch of facial supplying suborbital canal ; 

 d, dentary ; fr, frontal ; Jim, hyomandibular ; hm.f, hyomandibular branch of facial supplying 

 its lateral-line canal ; iop, interopercular ; 1, ' lachrymal ' ; I.I, lateral-line branch of vagus ; 

 l.o, lateral -line ossicles; mpt, metapterygoid; mx, maxilla; n, nasal; oc, crest of supra- 

 occipital ; op, opercular ; pf, prefrontal ; pmx, premaxilla ; pop, preopercular ; pst, post- 

 temporal ; 7, quadrate ; r.d, branch of facial supplying region of dorsal fin ; r.fv, dorsal 

 recurrent branch of facial ; rv, branch of facial supplying region of pectoral fin ; s.o, superior 

 ophthalmic branch supplying supraorbital canal ; sob, suborbital ; sop, subopercular. 



(Cyttidae, Scorpaenidae, Triglidae (Boulenger [42], Eidewood 

 [362-65])). Their union in such cases may be secondary. 



Frequently, especially in the higher forms (Acanthopterygii), 

 not only the basioccipital, but the exoccipitals as well, bear articular 

 facets for the vertebral column, and join below the foramen 

 magnum. 



Two more characteristics of the Teleostean skull may be 

 noticed : the presence of a supraoccipital bone, the origin of which 

 has already been discussed (p. 326) ; and the fact that the vomer 

 is single and median, not paired as in almost all lower forms. 



No certain trace of either the splenial or the coronoid has been 

 found in the lower jaw of a Teleost ; but the median gular is preserved 



