SMITH: ELOPIFORMES. NOTACANTHIFORMES AND ANGUILLIFORMES 



Fig. 52. Leptocephali of (D) Bascamchthys sp.; (E) Acromycter sp.; (F) Hildebrandia; and (G) Dysomma anguillare. 



crucial. If it is a synapomorphy, then the congruence between 

 it and the lower-jaw character reinforces the naturalness of the 

 Elopomorpha. Furthermore, it is a more complex character, thus 

 less likely to show parallelism than a simple process like the 

 fusion of two bones in the lower jaw (which, indeed, has hap- 

 pened independently in some osteoglossomorphs). 



To explore this matter, we must first establish clearly what a 

 leptocephalus is. If, as some have maintained, it were simply a 

 ribbon-like larva with a posterior anus and a dorsal fin that 

 moves forward at metamorphosis, then it would tell us little 

 about elopomorph phylogeny. Many lower teleosts have such 

 larvae. A leptocephalus is considerably more than this, however. 



