PISCES, TRUE FISH 



467 



mesoclavicle, and infraclavicle, supports the pectoral fin which con- 

 sists of a row of hasal elements, and distal to this, a row of radial ele- 

 ments. The most anterior radial is completely ossified, terminates 

 in a sharp spine, and has the posterior edge serrated. In addition, 

 it has a poisonous secretion with which to inflict wounds. These 

 are much stronger in the bullhead than in the perch. The bullhead 

 has a rudimentary pelvic girdle, but the perch does not. It consists 



Fron tal 

 Postfrontol 

 Parasph enoid 

 Prefrontal 



Nasal 

 Premaxilfa 



L acrimal 



Suborbital 



Ectopteryg old 



Maxil/a- 



Denfary 



A rticular 



Angular 



Ceratohyoid 



Hypohyal 

 Urohyal 



Supraocopital 



|— Paris tal 



Epiotic 



— Po St temporal 

 Pterotic 

 -Hyomandibuhr 

 -Opercular 

 r-Entopteryyoid 

 ^ Met op terygoid 

 Quadrate 

 Symplectic 



Preopercular 

 Subopercular 

 Brancti/osteyal Pay 

 Inf er opercular 



Pig. 255. — Lateral view of tlie sltull of tlie yellow perch, Perca flavescens. (Drawn 



by B. Galloway. ) 



of two similar ischiopubic plates united in the middle. Posterior to 

 these in the midline is a platelike fusion of the basals of the fin. 

 The radials are all fibrous. The anal fin and the dorsal fin are sup- 

 ported by interspinous bones. The anterior ray of the dorsal is a 

 bony spine. 



Muscular System and Locomotion 



Locomotion is not the only function of the voluntary muscular 

 system, but it is an important one. In addition to this function, 



