3D THE SESAMOID ARTICULAR 



THE ANACANTHINI. 

 Melanogrammus aeglifinus, Brosme brosme. 



The sesamoid articular is large and is attached against the ectosteal 

 plate just at the end of the endosteal process. It extends downward 

 somewhat behind Meckel's cartilage, but its bulk is above the cartilage 

 and arches over its upper surface. 



Microgadus tomcod. 



The condition of the sesamoid articular is most surprising, for it 

 is apparent that part of it at least is endosteal in origin, ossifying directly 

 from Meckel's cartilage. For a short distance in front of the endosteal 

 process Meckel's cartilage is as usual, then it is abruptly ossified in a rod 

 of bone in front of which, as it runs toward the dentary, it is again carti- 

 laginous. The posterior outer part of the ossification is enlarged against 

 the ectosteal plate, and to this enlargement the stout adductor tendon is 

 attached. It appears evident that the enlarged outer portion is the usual 

 sesamoid articular, and that Meckel's cartilage in ossifying has become 

 anchylosed with it. The part anterior to the enlarged portion is a white, 

 poorly organized, granular bone, but at the enlargement it is clear and 

 dense. Several speciments between 8 and 10 inches in length were exam- 

 ined, and considerable variation found in the length of the ossified por- 

 tion of Meckel's cartilage. 



Fig. 14. MICROGADUS TOMCOD 



an, angular ; d, dentary ; ecpl, ectosteal plate ; epr, endosteal process ; me, Meckel's 

 cartilage; sa, sesamoid articular. 



