FOSSIL AND RECENT 187 



and Denticipitidae). Subsequent work has indicated that the clupeiforms possibly 

 represent yet another attainment of the teleostean grade (Greenwood 1970b). The 

 nearest relatives of the Elopiformes were thought by Greenwood et al. (1966) to be the 

 Anguilliformes and the Notacanthiformes. Together these orders were grouped in 

 a Division I (subsequently named Cohort Taeniopaedia by Greenwood, Myers, 

 Rosen & Wietzman 1967) by virtue of the fact that members of all three orders have 

 a leptocephalus larva, and certain other characteristics (Greenwood et al. 1966) ; the 

 Elopiformes share the presence of rostral ossicles with the Notacanthiformes, and the 

 Notacanthiformes are related to the Anguilliformes by a similarity in swimbladder 

 anatomy. 



(b) Salient features of the Elopiformes and the relationship with other ' lower teleosts ' 



The following list of salient characters has been drawn up to serve three main 

 purposes : to indicate the wealth of primitive characters shown by the elopiforms ; 

 to serve as a reference point by which comparisons with other teleosts may be made ; 

 and to supplement the diagnosis given on p. 6. 



1. Parietals in contact medially. 



2. Dermethmoid separate from underlying mesethmoid. 



3. Supraoccipital small, supraoccipital crest weakly developed. 



4. Nasals slender, laterally placed. 



5. Neurocranium well ossified in the otic region. 



6. Post-temporal fossa with roof. 



7. Subtemporal fossa large. 



8. Orbitosphenoid and basisphenoid well developed. 



9. Parasphenoid with teeth. 



10. Anterior myodome bone absent. 



11. Pars jugularis long ; separate lateral openings for the hyomandibular ramus 

 of VII, jugular vein and orbital artery. 



12. Hyomandibular broad, orientated vertically or nearly so. 



13. Palatine composed of separate autopalatine (or palatine cartilage) and 

 dermopalatine. 



14. Premaxilla and maxilla entering gape. Supramaxilla(e) present. 



15. Endochondral elements of the gill arches ossified, remaining separate from 

 the dermal elements. 



16. Basibranchial (and usually a basihyal) tooth plate well developed. 



17. Ceratohyal composed of anterior and posterior ossifications, separated by a 

 narrow band of cartilage. 



18. Two hypohyals. 



19. Urohyal shallow. 



20. Infraorbital series composed of six elements. The first is large and is followed 

 by a narrow second element. 



21. Antorbital with associated sensory canal. 



22. Infraorbital sensory canal branches anteriorly to form an antorbital branch 

 and an ' ethmoid ' branch. 



