THE SESAMOID ARTICULAR 



Macrorhamphosus sagifue. 



At the upper edge of the broad Meckel's cartilage is a rather wide, 

 disk-like sesamoid articular placed flat against the ectosteal plate, con- 

 siderably above the endosteal part of the articular, and directly below the 

 ascending process of the dentary. It extends upwards more than usual, 

 thus approaching the condition of the Synentognathous fishes. 



Fistularia petimba. 



The dentary and articular are very complex in shape. Each of them 

 has three forks, which more or less interlock. The middle fork of the 

 dentary (by far the largest) fits between the middle and lower forks of 

 the articular in a deep notch that extends back nearly to the condyle of 

 the quadrate, thus almost dividing the articular into two parts. Directly 

 above this division in the articular are the endosteal process of the articu- 

 lar and Meckel's cartilage. The upper forks of both elements arch up- 

 ward, leaving an open space, above which they nearly meet. It is to 

 the posterior edge of this upper fork of the articular, to a small process 

 of bone, that the adductor tendon is attached. The process is remote from 

 Meckel's cartilage, and is probably not the homolog of the sesamoid 

 articular. In the smallest specimen available (5 inches long) no suture 

 was apparent to indicate a separate element in this region. 



Aulostoma valentini. 



The elements of the mandible differ from those of Fistularia only 

 in unimportant details. The upper fork of the dentary is scarcely devel- 

 oped, and that of the articular does not arch over an open space, but the 

 posterior part of it bears a process (larger than in Fistularia) to which 

 the adductor tendon is attached. 



Aulorhynchus flavidus, Aulichthys japonicus. 



The sesamoid articular is a very large plate, lying flat against the 

 ectosteal part of the articular, and extending up from Meckel's cartilage, 

 which it only barely touches, towards the coronoid region. To its upper 

 end is attached a strong tendon, and to the coronoid process is attached 

 a smaller, more fibrous one. 



