i6o 



ELOPIFORM FISHES 



dsp 



sop 



10 mm 



Fig. 80. 



Albula vulpes (Linnaeus). Cranium in left lateral view. 

 Composite of several B.M.N.H. specimens. 



process articulating with the mesethmoid ; posteriorly there is a large posterior 

 (lateral ethmoid) process. The precocious ossification of these processes should 

 not be interpreted as two embryonic divisions as Ridewood (1904 : 51) implied. 

 Rather, these processes ossify early in response to a functional need. The dermo- 

 palatine is larger than in pterothrissids and carries many more teeth. The ectoptery- 

 goid is relatively large (cf . Pterothrissus) and bears a well-developed process upon its 

 lateral surface. Ridewood (1904 : 51) reports the presence of a few ectopterygoid 

 teeth but I have seen no example with teeth. The dentition of the endopterygoid 

 is similar to that on the parasphenoid. 



Dermal upper jaw. The upper jaw is formed by the premaxilla and the maxilla, 

 the latter taking little part in the functioning of the jaw. The premaxilla bears on 

 its outer surface a series of struts which form an incomplete outer wall to the pre- 

 maxillary sensory canal. Anteriorly the premaxilla articulates with the ethmoid 

 region by two medially directed heads, one above the other. Such a double articula- 

 tion is not found in other albuloids and probably arose by a subdivision of a single 

 elongate facet like that in Pterothrissus. The double articulation makes union 

 with the ethmoid very strong and virtually immovable. The oral border of the 

 premaxilla bears a band of fine, pointed teeth. 



The edentulous maxilla is narrow anteriorly, but deepens posteriorly where it 

 is partially overlapped by a single supramaxilla. The anterior end of the maxilla 

 is turned inwards and is slightly swollen where it forms two rounded prominences. 



