178 ELOPIFORM FISHES 



Similarly, the infraorbitals are incompletely known. The orbital margin of this 

 series is gently rounded, as in Albula but in contrast to Pterothrissus. Anteriorly, 

 the dorsal margin of the first infraorbital is straight and inclined towards the snout 

 tip. The first infraorbital overlaps the dorsal half of the maxilla. The posterior 

 members of the series cover the cheek region posteriorly to the level of the hyo- 

 mandibular. The orbital margin of the infraorbitals is rolled over laterally to provide 

 a partial protection for the infraorbital sensory canal. 



Opercular series. The operculum is as wide as it is deep. Its anterior and dorsal 

 margins are straight. The posterior margin passes ventrally and slightly posteriorly 

 before turning sharply to present an almost horizontal ventral margin. The oper- 

 culum forms a comparatively small part of the entire cheek region. 



The suboperculum is a large element as in all albuloids. The posterior and ventral 

 margin is smoothly rounded and continues the contour of the operculum. Anteriorly 

 the suboperculum sends up a small dorsal wing. The shape of the interoperculum 

 could not be determined. 



The preoperculum is incompletely known. The anterior margin lies tightly against 

 the hyomandibular, symplectic and quadrate. A deep groove, which is partially 

 overlain by bone, runs close to the anterior margin and represents the path taken 

 by the preopercular sensory canal. 



Pectoral girdle and Jin. Dorsally the pectoral girdle is attached to the neurocranium 

 by the small post-temporal. Three limbs are directed anteriorly from the main 

 body of the post-temporal which is represented by a small triangular plate. One 

 such projection (the dorsal limb) reaches above the epiotic to which it was no doubt 

 connected by ligaments. Another is short, laterally directed and lies in juxtaposition 

 to the postero-lateral corner of the pterotic and is homologous with a similar limb 

 seen in Albula. The third limb (the ventral limb) passes antero-ventrally to contact 

 the neurocranium in the region of the intercalar. 



The supracleithrum overlaps the cleithrum ventrally and is itself overlain dorsally 

 by the post-temporal. The supracleithrum is longer than broad, with its anterior 

 and posterior margins parallel. From its union with the post-temporal the bone 

 slopes postero-ventrally. 



The cleithrum is, as usual, the largest element of the girdle. As seen in lateral 

 view the bone is tapered both dorsally and ventrally. The posterior margin slopes 

 ventrally at a steep angle and in this respect resembles Pterothrissus. The endo- 

 chondral elements are too incompletely known to warrant comment. However, in 

 lateral view the posterior limit of these elements lies behind that of the overlying 

 cleithrum, as in all albuloids. 



There are at least 12 pectoral fin-rays (Davis 1887 quotes a figure of 14 for all 

 species here considered as Lebonichthys). The first ray is unbranched. The 

 dichotomy of the inner rays is confined to the distal third of their length. A small 

 triangular splint is associated with the base of the outer fin-ray. 



Pelvic girdle and fin. The only evidence of the pelvic girdle is a small, trans- 

 versely orientated strip of spongy bone immediately anterior to the bases of the fin- 

 rays. The anterior half of the pelvic girdle, if present, was probably represented by 

 cartilage. 



