FOSSIL AND RECENT 



fa mx 



81 



SO s c 



asp 



Fig. 41. 



soc 



Promegalops sheppeyensis Casier. Neurocranium in dorsal view. 

 From holotype. 



the ascending wings ; the quadrate/mandibular articulation lies beneath the middle 

 of the orbit (only known in P. signeuxae) ; lower jaw protrudes beyond the pre- 

 maxilla (only known in P. signeuxae) ; operculum exhibits an antero-dorsal indenta- 

 tion (only known in P. signeuxae) . 



In all these respects Promegalops is more advanced than Protarpon, and is inter- 

 mediate between Protarpon and Megalops. 



Promegalops differs from Tarpon in the deep neurocranium, the angled parasphe- 

 noid and the general proportions of the otic region of the neurocranium. Such 

 features are found in Megalops and are considered to be advanced. Despite the 

 close similarity between Promegalops and Recent Megalopidae (in particular Mega- 

 lops) there are certain features of the Eocene species which may be considered primi- 

 tive or diagnostic. Primitive features include the shallow lower jaw, with a low, 



6 



