6 THE SESAMOID ARTICULAR 



Where the term 'endosteal' or 'ectosteal part of the articular' is used 

 it does not mean that these elements are necessarily separate. Nearly 

 always the anterior end of the endosteal part remains distinct from the 

 ectosteal part, though no trace of suture may remain. The endosteal 

 part forms the surface for the articulation of the quadrate, and usually 

 projects forward in a process, which I have herein referred to as the 

 endosteal process. The process abruptly becomes Meckel's cartilage 

 (or more correctly Meckel's cartilage abruptly ossifies to form the endo- 

 steal process). Often the anterior part of the endosteal process is of 

 the same size and shape as Meckel's cartilage, and the line of demarca- 

 tion between the two is difficult to appreciate, by sight alone, until the 

 latter begins to dry. The ectosteal part of the articular, usually herein 

 called the ectosteal plate, lies outward from the endosteal part and forms 

 the greater part of the bone. It is the continuation of the part articu- 

 lating with the dentary, sheltering Meckel's cartilage on the outer surface. 



I may here point out the danger of reporting on the absence of the 

 sesamoid articular in material that the investigator has not prepared for 

 himself, for it is often so loosely attached to the other elements of the 

 mandible, and so firmly to the tendon, that in cleaning the bones it is 

 easily removed with the latter. For instance, I found it in all of the 

 Clupeoid forms that I examined, though in several of them it has been 

 reported absent. 



It was the original intention to investigate the development of the 

 bone; but from lack of good material it appears better to publish the 

 paper in its present form, reserving the development for the indefinite 

 future when, it is hoped, material shall have accumulated to illustrate 

 the various phases of it. 



SYNONYMY 



Operculaire Cuvier (C. & V. Hist. Nat. Pois., 1827). 



Kronenforsatz des Unterkiefers, pars coronoidea mandibulae Erdl 



(Abhand. Bayer Akad. Wiss., V I, 1847). 

 Ossicle C. Bridge (Jour. Anat. Phys., XI, part 4, 1877). 

 Sesamoidverknocherung Vetter (Jena Zeitschr., XII, 1878). 

 Coronoid Cope (Proc. Am. Phil. Soc., XVII, 1878). 

 Addentary Gill (Proc. U. S. Nat. Mus., XVIII, 1895). 

 Sesamoid articular Ridewood (Proc. Zool. Soc. Lond., 1909). 



