FOSSIL AND RECENT 



in 



55 



Tp ce 



grah 



dhh 



brr 



Fig. 25. Tarpon atlanticus (Cuvier & Valenciennes). Hyoid bar and branchiostegals 

 (except uppermost ray) of right side in A, medial view and B, lateral view. 



first infraorbital there is a prominent knob articulating with the maxilla. Infra- 

 orbitals 3, 4 and 5 form a broad, thin bony plate. The dermosphenotic is a narrow 

 bone which tapers as it curves anteriorly to almost touch the supraorbital. It is 

 considerably stouter than any other infraorbital. 



Hyoid arch, gill arches and gular plate. The ceratohyal, as usual, comprises 

 anterior and posterior elements which are united by cartilage. A short, stout inter- 

 hyal is connected to the posterior ceratohyal by cartilage. The upper and lower 

 hypohyals are synchondrally united to one another and to the anterior ceratohyal. 

 The medial surface of the lower hypohyal bears a small ovoid facet to which a liga- 

 ment from the urohyal is attached. A medial prominence on the upper hypohyal 

 lies against the basihyal. The afferent hyoidean artery pierces the medial surface 

 of the lower hypohyal. From here the artery passes into the upper hypohyal, 

 emerges from its dorsal surface, and runs posteriorly in a groove on the lateral face 



