20 ELOPIFORM FISHES 



Mandible. Little may usefully be added to what Ridevvood (1904) has described 

 in Elops saurus. Mention may be made of the deep fossa on the medial surface of 

 the dentary which receives the A w division of the adductor mandibulae. This fossa 

 is relatively deep in Elops, its development probably being advanced and perhaps 

 correlated with the predatory habits of this genus since it is absent in the micro- 

 phagous clupeoids. 



Circumorbital series. The circumorbital ring is incomplete dorsally. The supra- 

 orbital is the only anamestic component of the series. It is a narrow bone which lies 

 close against the frontal. The ventral end of the supraorbital is overlain by the 

 antorbital. This latter bone and the snout ossicles have been described and figured by 

 Nybelin (1956, 1967a) in Elops saurus and the situation is the same in E. hawaiensis. 



The first infraorbital is very deep anteriorly but shallow posteriorly. Charac- 

 teristically the first infraorbital contacts the supraorbital and so excludes the antor- 

 bital from the orbit. The second infraorbital is very short and shallow and meets 

 the expanded third infraorbital in an oblique suture. The fourth and fifth infra- 

 orbitals, like the third, are longer than deep. The sixth infraorbital, or dermo- 

 sphenotic, consists of a shallow base which is produced antero-dorsally as a process 

 which lies tightly against the frontal. 



Hyoid arch, gill arches and gular plate. These structures and associated dermal 

 elements have been dealt with in various papers ; the hyoid and gill arches by 

 Ridewood (1904) and especially Nelson (1968a, b, E. hawaiensis, and 1969a), the 

 dentition of the mouth cavity by Nybelin (1968) and the gular plate by Jessen 

 (1968). Although the above authors described Elops saurus there is little difference 

 in E. hawaiensis. 



dhh 



vhh ace 



3mm 



1 



Fig. 7. Elops hawaiensis Regan. Hyoid bar and branchiostegal rays in left lateral view ; 

 this and Text-figs. 8-n based on an alizarin preparation of B.M.N.H. 1962. 4. 3.1, 

 62 mm S.L. 



