SKELETON OF HADDOCK 



621 



In the opercular fold are four membrane bones. 



There are four pairs of complete branchial arches, which are divided 

 into various parts. Of these the most interesting are the two superior 

 pharyngeal bones, which he in the roof of the pharynx and bear teeth, 

 and are formed by the coalescence of the dorsal elements of the arches. 

 Their teeth bite against those of the inferior pharyngeal bones, which 

 lie on the floor of the pharynx, and represent the fifth branchial arches. 



The limbs and girdles. — The dermal rays of the pectoral fin are 

 attached to four small brachial ossicles ; these articulate with a dorsal 

 scapula and a more ventral coracoid ; both of these are attached to the 



COT. 



Fig. 356. — Pectoral girdle and fin of cod. 



fr.. Fin-rays ; b.o., brachial ossicles ; cor., coracoid ; sc, scapula ; 

 d., clavicle ; p.cl., post-clavicle ; s.cl., supra-clavicle ; p.t., 

 post-temporal. 



inner face of a large clavicle or cleithrum, which almost meets its fellow 

 in the mid-ventral line of the throat. From the clavicle a slender 

 post -clavicle extends backwards and downwards ; while a stout supra- 

 clavicle extends from the dorsal end of the clavicle upwards to 

 articulate with a forked post -temporal, which articulates with the back 

 of the skull. It must not be assumed that the elements of this girdle 

 are directly comparable to those of a higher Vertebrate, although the 

 nomenclature is the same. 



The pelvic girdle seems to be absent, as in almost all Teleostomes, 

 but its place is taken by a thin plate of bone, apparently due to a 

 fusion of some basal elements of the pelvic fins. 



