72 



ELOPIFORM FISHES 



fahm 



fuv 



asp 



Whm 



30mm 



par 



ptfc 



fica 



Fig. 36. Protarpon priscus (Woodward). Neurocranium, right lateral view of the otic 

 region. Based on B.M.N. H. P. 356 and P. 26694 (formerly P.1698). 



ventral margin to the post-temporal fossa and at this point the bone bears a promi- 

 nent groove which leads towards, but fails to reach, the occipital condyle. Ventrally 

 the exoccipitals form with the basioccipital a tripartite suture with the first vertebral 

 centrum. This centrum is functionally part of the neurocranium. The centrum 

 exhibits a shallow, asymetrically placed notochord pit. The outer surface of the 

 centrum is generally smooth save for a few longitudinal grooves on its dorsal half. 

 If, as in the Recent megalopids, a neural arch was attached to this element, its union 

 with the centrum must have been weak since there is no evidence of articulatory 

 facets. 



A lateral view shows that the neurocranium is deepest at the occiput, a resemblance 

 to Tarpon. The dilatator fossa is shallow and roofed by the pterotic which forms 

 much of its inner wall and floor. The hyomandibular facet slopes ventro-anteriorly, 

 there being a slight downward and lateral flexure at the extreme anterior end. 

 The facet consists of two oval depressions linked by a somewhat narrower groove. 

 Like the dilatator fossa the hyomandibular facet is formed largely by the pterotic. 

 The anterior region of both the facet and the fossa is formed by the autosphenotic 

 which is produced laterally as a weakly developed autosphenotic spine. 



The subtemporal fossa is large and formed by the pterotic, exoccipital and prootic, 

 which line the dorsal, postero-ventral and antero-ventral regions respectively. It 



