THE SESAMOID ARTICULAR 



THE AMPHACANTHI. 



Siganus fuscescens 



i 



The sesamoid articular is broad and flat; its flat side is firmly at- 

 tached against the ectosteal plate, and its lower edge rests on the endo- 

 steal process and Meckel's cartilage. The tendon is attached near its 

 center. 



THE PLECTOGNATHI. 

 Balistes vetula. 



The sesamoid articular is a thick nodule of bone on the upper sur- 

 face of the endosteal process (whose limits are obscure) and Meckel's 

 cartilage. 



Spheroides annulatus. 



In this form the sesamoid articular more evidently originates within 

 the tendon than in any other example I have encountered. Near the 

 mandible end of the tendon an area of it is ossified, forming a shaft of 

 bone about four times as long as broad. The tendon is attached to the 

 region of the endosteal process, which is obscure, at some distance behind 

 Meckel's cartilage. Between the mandible and the ossified portion of the 

 tendon (sesamoid articular) is a considerable area of unossified tendon. 

 A large part of the inner surface of the dentary as well as the upper angle 

 (coronoid region) of the articular and dentary, is covered by a great 

 mass of tendon from the adductor muscles. The tendon that forms the 

 sesamoid articular ossification is below this mass of tendon and compara- 

 tively small. 



Fig. 13. SPHEROIDES ANNULATUS 

 a, articular; d, dentary; sa, sesamoid articular. 



