26 



HIGH SCHOOL ZOOLOGY. 



25. "Very similar in constrnction to the hyoitl arch aro the 

 succeeding five branchial arches, the upper ends of which curve 

 in beneath the skull, to the base of which they are attached by 

 muscle and ligaments, while the lower ends meet in the floor of 

 the mouth. Epi- and cerato- branchials form the greater part 

 of each ai-ch, but the upper ends are formed of pharyngo- 

 branchials, and the lower of hypo-branchials, united by certain 

 unpaired pieces, the basi-branchials. (Fig. 9). 



Fig. 9. -Visceral Skeleton of Catfish. 

 H. hypohyal; ch, oeratohyal ; eh, epihyal ; i, interhyal : b', first basibranchial ; 

 hbi, cbi, eb', hypo- cerato- and epibranchiala of first arch ; o, ocsophajfus; ep and hp, 

 epi- and hypopharyngeal tooth plates. 



26, The teeth on the premaxillaj and mandible have been 

 refer'^ed to above, but the catfish has also a formidable array of 

 teeth further back in the cavity of the mouth. The four phites 

 which carry these are known as the superior and inferior 

 pharyngeal plates, the former of which are attached below the 

 upper ends of the third and fotirth arches, while the latter are 

 co-ossified with the ceratobranchials (the only parts jiresent) of 

 the fifth arch. 



27. Appendicular Skeleton. — The pectoral fin is sup- 

 ported by a bony arch known as the pectoral arch or girdle, 



