7 6 



ELOPIFORM FISHES 



narrow dorsally, but ventrally it widens considerably. The concave anterior margin 

 of the preopercular is thickened mid-way along its length to receive part of the super- 

 ficial adductor mandibulae musculature. The preopercular sensory canal ran close 

 to the anterior margin and opened to the surface of the bone by several large pores. 



The operculum is a large bone showing a rounded dorsal margin. The ventral 

 margin is inclined. Like the other opercular bones the surface is marked by ridges 

 radiating from the centre of ossification. The suboperculum continues the contour 

 of the operculum and is partially overlapped by the latter. An interoperculum is 

 present beneath the preoperculum. 



There are at least 20 branchiostegal rays. The posterior members of the series 

 are broad and bear the same surface markings as the opercular bones. The anterior 

 branchiostegal rays are fine and needle-like and when the mouth was closed the 

 anteriormost branchiostegal rays were situated beneath the level of the first infra- 

 orbital. 



Between the lower jaw rami and overlying the anterior branchiostegal rays is a 

 large gular plate, at least half as long as the mandible. The gular plate is widest 

 posteriorly where the width is equal to one-third of its length. 



asp 



pto 



epo 



soc 



30 mm 



Fig. 39. Protarpon cf. prisons. Neurocranium, dorsal view of the otic region. 



From B.M.N. H. P.4153. 



