24 ELOPlDvE. 



Prsemaxillary single; a very large supratemporal 



bone ; symplectic absent ; opercular bones 



hidJen under the skin ; gill-opening narrow . 2. MoRMYRlD^, p. 29. 

 Prgemaxillary paired ; supratemporal bone small ; 



symplectic present ; belly with a double bony 



serrature 3. Notopteeid^, p. 145. 



2. Ribs inserted on parapophyses ; pectoral fins folding against belly, like 

 the ventrals. 

 Prcemaxillary paired ; interoperculum and sub- 



operculum present ; ventral fins distant from 



the pectorals 4. Osteoglossid.e, p. 148. 



Pra.'maxillary single ; interoperculum and suboper- 



culum absent ; ventral fins near the pectorals . 5. Pantodontid.e, p. 151. 



B. Supraoccipital in contact with the frontals ; suboperculum and interoper- 

 culum well developed. 



1. Gill-openings wide ; body covered with scales ; mouth not protractile. 

 Postclavicle on outer side of clavicle ; no adipose 



dorsal fin C. Clupeid.e, p. 153. 



Postclavicle on inner side of clavicle ; an adipose 



dorsal fin 7. Salmonid.e, p. 1G5. 



2. Gill-openings narrow. 



Bod}'^ covered with scales; interoperculum enormous, 

 covering the gular region ; mouth very pro- 

 tractile, superior 8. Phractol.emid.9C, p. 167. 



Body scaly ; mouth not protractile, inferior ... 9. Kneriid2E, p. 1G9. 



Body naked ; mouth not protractile, inferior ; 



fymplectic absent 10. Cromeriid.e, p. 173. 



Fam. 1. ELOPlDiE. 



Margin of the upper jaw formed by the prcemaxillaries and tlie 

 maxillavies, the latter much developed ; parietal bones forming a median 

 suture above the supraoccipital, or separating it from the frontals ; 

 symplectic present ; interoperculum and suboperculum well developed ; 

 an intergular or sublingual bone, between the rami of the mandible. 

 Phaiyngeal teeth. Branchiostegal rays very numerous (more than 20). 

 Gill-openings wide. Ribs mostly sessile, behind a parapophysis ; epi- 

 neurals, no epipleurals. Pectoral fins inserted very low down, folding 

 like the ventrals. Ventral fins with 10 to 16 rays. 



Two genera, of wide distribution in tropical and subtropical seas : — 



Scales small ; dorsal a little longer tnan anal ... 1. Elops, L., p. 25. 

 Scales large ; dorsal a little shorter than anal, with 



the last r.'iy much produced 2. il/t'^a/o/^s, Laccp., p. 27. 



