74 ELOPIFORM FISHES 



opening is continuous with a short horizontal groove upon the prootic. At the level 

 of the foramen for the jugular vein, the medial surface of the prootic is produced 

 horizontally to meet its partner of the opposite side in the prootic bridge. This 

 bridge is notched anteriorly in the mid-line where it forms the posterior border to 

 the pituitary foramen. The abducens nerve pierced the prootic bridge. The an- 

 terior, vertical face of the prootic is pierced by a large trigemino-facialis foramen. 

 The details of the trigemino-facialis chamber are similar to those described for 

 Tarpon. Medial to this foramen lies a small oculomotor foramen. 



The parasphenoid, which is only seen in one specimen (B.M.N.H. P. 26694), 

 extends almost to the posterior end of the neurocranium. Throughout its known 

 extent (i.e. to mid-orbital level) the bone is relatively narrow. Below the orbit the 

 parasphenoid bears a thin row of teeth in the mid-line. The teeth extend posteriorly 

 to beneath the ascending wings. Ventrally the posterior end of the parasphenoid 

 shows a deep median groove which fades anteriorly. A faint lateral groove is seen 

 immediately behind the small ascending wings. The internal carotid foramen lies 

 at the base of the ascending wing. 



Hyopalatine bones. Very little is known of this series. The hyomandibular 

 articulates with the neurocranium by a single expanded head which is weakly divided 

 into anterior and posterior regions. The shaft of the hyomandibular is inclined 

 ventrally and slightly posteriorly. Its ventral limit is unknown as it is overlapped 

 by the large metapterygoid. The triangular quadrate is slightly longer than deep 

 and bears a large condylar surface ventrally. Posteriorly the quadrate is deeply 

 grooved and receives the rod-like symplectic. The posterior quadrate border is 

 thick and provided an attachment point for the deeper divisions of the adductor 

 mandibulae musculature. The preoperculum rests against the posterior margin 

 of the quadrate. As in Tarpon there is a small notch upon the quadrate immediately 

 behind the articulatory condyle. 



Dermal upper jaw. The upper jaw extends from the snout to a level behind the 

 orbit. The oral margin of the jaw is slightly curved, less so than in Tarpon or Mega- 

 lops. The premaxilla is relatively small with its oral border equalling one-quarter 

 of the total jaw length. The dorsal border of the premaxilla is produced into a 

 prominence (it hardly deserves the term articular process) which fits into a slight 

 groove upon the head of the maxilla. 



The maxilla is a moderately deep, parallel-sided bone, overlain posteriorly by 

 two large supramaxillae which resemble those of Tarpon. The head of the maxilla 

 tapers anteriorly before expanding into a dorsal palatine malleolus and an anterior 

 ethmoid prominence. 



The oral border of both premaxilla and maxilla bears a thin band of very small 

 villiform teeth. Their posterior extent upon the maxilla is unknown. There appear 

 to be fewer teeth than in either of the Recent megalopids. 



Mandible. The mandible projects in front of the premaxilla. The oral border 

 curves slightly upwards from the shallow dentary symphysis. At one-third of the 

 way back the oral border rises more steeply to form a rather elongated coronoid 

 process, as in Recent megalopids. The teeth borne along the oral border are similar 

 to those on the upper jaw. 



