174 ELOPIFORM FISHES 



examples. The nasal is a thin, gutter-shaped element partially overlapping the 

 anterior end of the frontal. 



Of the lateral neurocranial wall little can be seen. Features which may be recog- 

 nized are a deep subtemporal fossa beneath the hyomandibular facet, a large otic 

 bulla which accommodated the sacculith, and a very small autosphenotic spine. 

 Imperfect suture lines between the various neurocranial elements are seen in some 

 specimens. The outline and contours of those which may be identified suggest that 

 the neurocranium is very much like that of Osmeroides latifrons. Significantly, 

 the intercalar is reduced to a small cap of bone postero-ventral to the subtemporal 

 fossa. 



The parasphenoid is distinctive in bearing a dentition similar to that of small 

 specimens of Albula vulpes. The bone is broad throughout its length. Posteriorly 

 it reaches the occipital condyle, while anteriorly it overlies the vomer beneath the 

 lateral ethmoid. At the level of the weakly defined ascending wings the para- 

 sphenoid exhibits a shallow angle. Posterior to this level the parasphenoid extends 

 back and terminates in two short prongs, between which there is a median ventral 

 groove extending forwards to the parasphenoid flexure. Beneath the orbit and part 

 of the lateral ethmoid the parasphenoid bears a tooth plate. Each of the many 

 teeth borne by this plate is hemispherical and bears a distinct translucent apical 

 cap of enamel. There is a large pulp cavity. The posterior teeth are the smallest, 

 the largest being found in the anterior third of the plate. Throughout the toothed 

 area very small teeth may be seen lying adjacent to large ones. Towards the lateral 

 margin of the plate there is a predominance of smaller teeth. The base of the 

 ascending wing of the parasphenoid is marked by a deep excavation at the bottom 

 of which lies the foramen for the internal carotid artery. The efferent pseudo- 

 branchial artery must have looped around the antero-dorsal margin of the para- 

 sphenoid ascending wing. 



The vomer is as wide as the anterior end of the parasphenoid, with which it is in 

 contact in an overlapping suture. No specimen shows definite evidence of vomerine 

 teeth although several small needle-like teeth, which may probably be referred to the 

 vomer, are often found in the snout region. 



Hyopalatine bones. The hyomandibular is stout and relatively short. Dorsally 

 the bone is thick and forms a single broad articular head. The bone projects an- 

 teriorly as a thin wing which meets the metapterygoid. Characteristically, there is 

 little or no overlap between these elements. The ventral part of the hyomandibular 

 slopes forwards as a stout shaft, the posterior margin of which is grooved for the 

 passage of the hyomandibular trunk of VII and the efferent hyoidean artery. The 

 opercular process is weakly defined. 



The metapterygoid is of irregular shape. Anteriorly this element overlaps the 

 endopterygoid while ventrally it is separated from the quadrate by a narrow inter- 

 space. The postero-ventral margin of the metapterygoid overlaps the symplectic, 

 as in other albuloids. 



The symplectic is long in Lebonichthys and provides a firm linkage between the 

 forwardly positioned quadrate and the ventral end of the hyomandibular. Pos- 

 teriorly the symplectic is somewhat flattened. 



