54 ELOPIFORM FISHES 



pointed, but much more sparsely distributed. Those on the ectopterygoid are 

 confined to the extreme lateral border. 



Dermal upper jaw. The upper jaw ends behind the eye. In young individuals 

 the jaw is relatively narrow with a slightly curved oral margin but in adult specimens 

 the jaw is deeper and the oral margin is markedly rounded. 



The premaxilla occupies 20 per cent of the total jaw length. Anteriorly the 

 premaxilla is deep, meeting its partner in the mid-line. The dorsal border is pro- 

 duced posteriorly as a rudimentary articular process which overlaps the maxilla. 

 The oral border of the premaxilla bears many small, pointed teeth. 



The maxilla is thin posteriorly but thickens anteriorly as it curves medially to 

 articulate with the ethmoid region by a slightly expanded head. A small palatine 

 process arises from the lateral face of the maxilla, beneath which there is a groove 

 receiving the posterior (dorsal) border of the premaxilla. Two supramaxillae over- 

 lap the dorsal margin of the maxilla. The smaller anterior supramaxilla is ovoid 

 while the larger posterior element has a spine passing dorsal to the anterior supra- 

 maxilla. A broad band of teeth is borne by the maxilla. The greater width of this 

 tooth band is on the medial side of the bone. 



Mandible. Although the total length of the mandible equals that of the upper 

 jaw, the mandible protrudes in front of the premaxilla and the mouth is upwardly 

 directed. The profile of the dentary symphysis continues that of the skull roof in 

 adult specimens, but in young individuals this is not so and the dentary symphysis 

 is relatively shallow. 



The dentary forms two-thirds of the mandible. The ventral margin is slightly 

 inflected. Anteriorly the dentary curves markedly inwards to the symphysis. For 

 one third of the mandibular length the oral margin of the dentary is parallel to the 

 ventral border, but behind this level the profile rises steeply to form much of the 

 elongate coronoid process. In young individuals the dentary is relatively shallower 

 and the oral margin is gently curved. Teeth are borne in a broad band along the 

 oral margin of the dentary. The tooth band increases in width posteriorly where it 

 spreads over the medial surface of the bone. Teeth borne by the dentary are similar 

 to those of the upper jaw and dermopalatine. On the medial surface of the dentary 

 there is a deep, anteriorly directed, crescent-shaped fossa which receives the anterior 

 end of the A w muscle. 



The articular forms the posterior part of the coronoid process and the outer portion 

 of the articulatory cup. The medial surface of the articular has a prominent ridge 

 which is continuous with a ridge upon the dentary. The endosteal articular forms 

 the inner portion of the articulatory cup and sends a short process forward on the 

 top of the articular ridge. A small sesamoid articular occurs anterior to the endo- 

 steal articular. 



Circumorbital series. This series is composed of seven bones, one of which, the 

 supraorbital, is an anamestic component. The antorbital is a narrow strut, inclined 

 antero-ventrally from its loose connection with the supraorbital. Part of the ventral 

 antorbital margin lies against the dorsal border of the lachrymal (the first infra- 

 orbital) . The latter element is rounded anteriorly. Posteriorly it narrows where it 

 is partially overlapped by the second infraorbital. On the antero-dorsal part of the 



