GREGORY: FISH SKULLS 



383 



projecting suspensoria, comprising especially the hyomandibulars and preoperculars. 

 Beyond the diverging palato-pterygo-quadrate legs are the widely arching halves of the 

 mandible. This abuts posteriorly on either side against the firmly fixed quadrate, while 

 its thickened distal ends are braced against each other at the symphysis. The thick sur- 



pf gpafc+h 



fr 



spho* 



Coryphcenoides cerapinus 



Fig. 262. Corypluenoides. 



angular process of the articular bone, together with the stout ossified Meckelian region of 

 the articular, afford insertion for the powerful adductor muscles, which stretch downward 

 and forward from the oblique antero-lateral faces of the suspensoria. The relatively stout, 

 partly inwardly directed teeth of the dentary do not occlude directly with the teeth on the 

 palatopterygoid and vomer, but when the mouth is closed by the strong adductor muscles 

 the mandibular teeth pass well to the outer side of the upper teeth. Hence the action here 

 is not so much a shearing as a squeezing and breaking action. The much smaller teeth on 

 the upper and lower pharyngeal bones may serve not so much for the trituration of small 

 pieces of food as for manipulating the food by differential movements of the various parts 

 of the mechanism, so as to facilitate the act of deglutition. 



From the under-side view the wide, inverted V of the mandible is followed by the still 

 more divergent inverted V of the lower hyoid arch, consisting of the thick basihyals, forming 

 the keystone, and the stout cerato- and epi-hyal bars, to which are attached anteriorly the 

 powerful geniohyoid muscles, and posteriorly the thick muscles that run backward to the 

 cleithra; besides this, the basihyal and glossohyal afford support to the rather small branchial 

 apparatus. 



The bracing of the mandible, of the diverging palatopterygo-quadrate legs and of the 



