186 ELOPIFORM FISHES 



order, was given as to the relationship existing between the Elopidae ( + Megalopidae) 

 and the Albulidae ( + Pterothrissidae) or to their relationship with other ' clupeiform ' 

 fishes. 



Bertin and Arambourg (1958) went one stage further by including the Elopidae 

 (containing the megalopids), Albulidae and Pterothrissidae in a suborder Elopoidei 

 of the order Clupeiformes (sensu lato). In the Elopoidei Bertin and Arambourg 

 {op. cit.) also included the extinct family Thrissopateridae (Thrissopater and Pachy- 

 rhizodus), an assemblage thought by the present author to be but distantly related 

 to the elopiforms. 



Although the elopids, megalopids, albulids and pterothrissids have been considered 

 closely interrelated by the above authors, the reasons put forward are based upon the 

 common possession of primitive and retentional features. Characters often quoted 

 as indicating relationship are : medially united parietals, gular plate, upper jaw 

 formed by both the premaxilla and maxilla, posterior circumorbitals large, opercular 

 apparatus complete, scapular foramen entirely enclosed, etc. Ride wood (1904 : 54) 

 recognized the fallacy of using such criteria when he stated ' Such resemblances as 

 exist between them [albulids and elopids] are explicable by the fact that neither has 

 departed to any great extent from the ancestral group from which all the Teleostean 

 fishes sprang. . . '. It is indeed true that none of the elopiform fishes has progressed 

 far beyond the pholidophorid stage. Elops is justifiably credited with being the 

 most archaic of living teleosteans and some authors have gone so far as to suggest that 

 Elops is a holostean. Saint-Seine (1949), for instance, places Elops in the Hale- 

 costomi and Nybelin (1956) suggested that Elops is as much a holostean as is Amia 

 or Lepisosteus. Gosline (1971 : 112, fig. 28) questions a close relationship between 

 Elops and Albula, and implies that elopoids and albuloids may each have closer 

 relatives outside the Elopiformes. 



Clearly a relationship, if it exists, between the Elopidae, Megalopidae and the 

 Albulidae and Pterothrissidae, must be based upon advanced and specialized charac- 

 ters inherited from the common ancestor. The presence of rostral ossicles and a 

 leptocephalus larva, both considered here to be advanced features, were recognized 

 by Bigelow (1963) as evidence of relationship, and this view is supported here. 



The classification of the Elopiformes I have used is essentially that of Greenwood 

 et al. (1966) with the addition of a new family, the Osmeroididae, to the Albuloidei. 

 I believe that this scheme most closely reflects the phylogeny of the elopiform fishes. 



The history of thought concerning the relationship of the elopiforms to other 

 ' lower teleosts ' has been stable. Most authors have placed the elopiform families 

 near to the clupeids with the implication that the latter are their closest living rela- 

 tives (Boulenger 1910 ; Berg 1940 ; Bertin & Arambourg 1958 ; and others). 

 Woodward (1901), perhaps significantly, dealt with the osteoglossids and noto- 

 pterids between the elopiforms and clupeids. 



Greenwood et al. (1966) consolidated a strengthening opinion that the ' isospondyls ' 

 represent an artificial assemblage and proposed a three- or fourfold origin of teleosts 

 from pholidophorid ancestors. In this scheme the elopiforms were considered to have 

 evolved from the pholidophorids independently of other lower teleostean fishes with 

 the possible exception of the Clupeiformes (Clupeidae, Engraulidae, Chirocentridae 



