FOSSIL AND RECENT 161 



The dorsal prominence probably corresponds to the palatine projection seen in 

 elopoids and osmeroidids ; the ventral projection corresponds to the maxillary head. 

 The maxilla is capable of moving independently of the premaxilla. 



Mandible. The mandible is short, with a deep coronoid process situated pos- 

 teriorly and a narrow symphysis. Both the endosteal articular and the sesamoid 

 articular are large. The mandibular sensory canal is contained within a deep trough 

 on the dentary and dermarticular. The dentition consists of a band of fine needle- 

 like teeth on the dentary. 



Circumorbital series. The supraorbital and antorbital are slender and form a thin 

 strut, as in Pterothrissus. Two rostral ossicles lie anterior to the first infraorbital 

 and as in other elopiforms are barely larger than the contained sensory canal. 



The infraorbital series of Albula is typical of that of other albulids but differs 

 somewhat from that series in the Pterothrissidae. The posterior infraorbitals are 

 wide and completely cover the cheek region. The dermosphenotic is large, its 

 posterior margin continuing that of the fifth infraorbital. As in Pterothrissus the 

 infraorbital margin is rolled, but in A. vulpes the sensory canal is better protected 

 by bone (cf . Text-figs. 80 and 66) . 



Cephalic sensory canal system. The system of canals upon the head is mainly 

 contained in large troughs. The supraorbital canal runs within the frontal from the 

 level of the autosphenotic to the level of the lateral ethmoid. Anterior to this the 

 canal continues in the frontal trough and the nasal ossicle(s) to end blindly anteriorly. 

 Gosline (1961) records a single median cavity separated from the supraorbital canal 

 of either side by membrane. The epithelium lining this cavity appears to be supplied 

 by a fine branch of the facial nerve and could therefore be related to the supraorbital 

 canal. 



The otic division of the cephalic sensory canal runs within the pterotic parallel 

 to its dorso-lateral edge. The canal opens posteriorly by two pores, one directed 

 laterally and joining with the preopercular canal, the other directed posteriorly and 

 receiving the supratemporal commissure and the lateral line. Innervation of the 

 otic canal is from two sources : anteriorly the otic branch of the facial pierces 

 the autosphenotic, and posteriorly a supratemporal branch of the vagus pierces the 

 lateral wall of the dilatator fossa. 



The lateral portion of the supratemporal commissure is contained within the supra- 

 temporal while the middle section lies in the skin. Neither the pterotic nor the 

 parietal is grooved, as they are in Pterothrissus. 



Hyoid arch, gill arches and gular plate. The ceratohyal consists of a stout posterior 

 element and a longer but narrower anterior element. The latter bears a deep groove 

 on the lateral surface for the reception of branchiostegal rays. The afferent hyoidean 

 artery does not pierce either hypohyal ; instead it passes upwards within the cerato- 

 hyal and runs back along a groove on the dorsal edge of the anterior ceratohyal. Of 

 the 15 branchiostegal rays, the anterior three lie free in the branchiostegal membrane. 



The gill arches are very similar to those of Pterothrissus. Minor differences that 

 do exist concern the teeth borne by the basibranchial tooth plate. In Albula vulpes 

 these teeth are hemispherical, irregular in size and show no pattern of size distribu- 

 tion. A basihyal tooth plate is absent. 



