THE SESAMOID ARTICULAR 17 



THE EELS. 



In all the examples examined the dentary forms a sheath about the 

 articular, hiding Meckel's cartilage completely from view, and covering 

 the anterior part of the sesamoid articular. The sesamoid articular ten- 

 don is well developed. 



Symbranchus marmoratus. 



A moderately large sesamoid articular is situated on the articular 

 above the endosteal process and base of Meckel's cartilage. The tendon 

 from the sesamoid articular is a flat band somewhat connected with a 

 similar band attached more posteriorly on the articular. A great mass 

 of tendinous tissue gives muscle attachment to the upper, posterior pro- 

 cess of the dentary. 



Anguilla chrysypa. 



The sesamoid articular is situated on the endosteal process of the 

 articular, and is covered anteriorly by the inner plate of the dentary, 

 under which it extends forward over Meckel's cartilage. 



Synaphobranchus pinnatus. 



The sesamoid articular is an exceedingly slender splint of bone cov- 

 ering Meckel's cartilage on its upper and inner surface, directly in front 

 of where the cartilage issues from the endosteal process of the articular, 

 and extending forward into the dentary sheath. 



Leptocephalus conger. 



In this form the articular is anteriorly divided. The lower division 

 is entirely outside of the dentary, running along its outer lower edge, 

 while the upper division is sheathed by the dentary. A very large sesa- 

 moid articular is on the endosteal part of the upper fork and forms with 

 it the cavity from which Meckel's cartilage issues, and which is usually 

 confined to the endosteal process, though here the sesamoid articular 

 forms the greater part of it. The sheath of the dentary fits tightly about 

 the articular and the sesamoid articular, leaving only a minute hole into 

 the dentary sheath above the sesamoid articular. 



Muraenesox coniceps. 



The sesamoid articular is on the endosteal process of the articular, 



