fenestrated and bears two rows of posteromedially cur\'ed 

 teeth. When drawn forward, the tooth plate is inverted into 

 the mouth opening; when drawn back, the rasping action 

 results. The protractor muscles lies below the basal plates, 

 the retractors above these plates. 



nasal capsule 

 na^sol tentacles subnasal cartilage I pa'atine corti 



nasal tube cartilage! 



The tentacles of the nasal and mouth openings are sup- 

 ported by cartilaginous rods. The ventromedial nasal ten- 

 tacle of each side is supported by the subnasal cartilage, the 

 dorsolateral nasal and the oral tentacle by the lingual appa- 

 ratus, and the labial tentacle by a small independent rod. 



otic capsule 



planum viscerale {internal hyoid) 



oral tentacle 



coronal cartilage 



labial tentacle 



cornual process 



posterior lingual cartilage 



palatine commissure 



ethmoid denticle 



hypophyseal cartilage external hyoid and" first branchial arch 



medial lingual cartilage 

 dentigerous cartilage 

 anterior lingual cartilage 



nasal tube cartilages 



coronal cartilage 

 cornual process, 



palatine commissure, 

 anterior lingual cartilage 



nasal capsule, 

 teeth of dentigerous cartilage 

 palatine cartilage, 

 hypophyseal cartilage 



otic capsule, 

 parabasal process 



B 



internal bronchial I 



velar skeleton 



dentigerous 

 cartilage 



tendon 

 anterior end of velar cartilage 



radix arcuum 



posterior lingual cartilage 



nasal tentacles 



oral tentacle 

 subnasal cartilage 



anterior lingual cartilages 



_ medial lingual cartilage 

 planum viscerale (cut off) 



velar skeleton 



Figure 5-28. Head skeleton of hAyxme. A, lateral view; B, dorsal view with right half of nasal capsule 

 cut away; C, dentigerous cartilage lying above anterior lingual cartilages; D, ventral view with left 

 posterior lingual cartilage cut away. (After Marinelli and Strenger, 1956) 



AGNATH FISHES 



133 



