22 



THE SESAMOID ARTICULAR 



Trachycorystes galeatus. 



The sesamoid articular extends over the top of Meckel's cartilage, 

 connecting the endosteal process and the ectosteal plate. The tendon is 

 very large and stout. 



Ictalurus furcatus. 



In this the sesamoid articular is as in Brachyplatystoma, but much 

 smaller and more slender. 



Selenaspis dowii, Sciadeichthys troscheli. 



In these the sesamoid articular is essentially as in Amiurus. 



THE GYMNOTID FISHES. 

 Electrophorus electricus. 



The sesamoid is here long and rod-like, and is situated against the 

 ectosteal part of the articular in front of the endosteal part. It lies on 

 and slightly arches over Meckel's cartilage. A large tubercle on its 

 posterior end gives attachment to a very stout tendon. 



Gymnotus carapo. 



The sesamoid articular is a very large flat bone situated above the 

 base of Meckel's cartilage and the endosteal process. It projects broadly 

 over the inner surface of the latter and is strongly articulated to it. To 

 a prominent tubercle on its posterior end a large tendon is attached. 



Fig. 10. GYMNOTUS CARAPO 



an, angular; d, dentary; cpr, endosteal process; me, Meckel's cartilage 

 sa, sesamoid articular ; t, tendon. 



