614 'PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



ce. 1/Atvrn\ line wanting; no gular plate. 



i. Mouth small, inferior, toothless, the maxillary simple or nearly so; 



stomach gizzard-like Dorosomatid.e, V 



ii. Mouth moderate, terminal, the maxillary of about three pieces; 



stomach not gizzard-like Clcpeid.e, VI 



in. Mouth subiuferior, very large, below the tapering, pig-like snout; 



maxillary very long Engraulid.e, VII 



cc. Dorsal fin inserteil far back, opposite anal. 



j. Anal lin very long; belly sharp-edged; air bladder cellular. 



Chirocentrid.e, VIII 

 jj. Anal tin moderate, belly rounded; deep-sea fishes, of loose organ- 

 ization; mostly blackish in color; mouth small, with small 



pointed teeth; air bladder wanting Alepocephalid^e, IX 



bb. Head and body covered with spinous scales; mouth with barbels; dorsal oppo- 

 site ventrals; anal short; no air bladder Gonorhynchice, X 



Family 1. ELOPID^E. 



Body elongate, more or less compressed, covered with silvery, cycloid 

 scales; head naked. Mouth broad, terminal, the lower jaw prominent. 

 Premaxillaries not protractile, short, the maxillaries forming the lateral 

 margins of the upper jaw; maxillary composed of about three pieces, 

 extending backward beyond the eye; an elongate bon}^ plate between 

 the branches of the lower jaw; bands of villiform teeth in both jaws 

 on the vomer, palatines, pterygoids, tongue, and base of skull; no large 

 teeth. Eye large, with an adipose eyelid. Opercular bones thin, with 

 expanded membranaceous borders; a scaly occipital collar. Gill mem- 

 branes entirely separate, free from the isthmus. Branchiostegals 

 numerous (29 to 35). Gill-rakers long and slender. Pseudobranchia; 

 present or absent. Belly not keeled nor serrated, rather broad and 

 covered with ordinarj^ scales. Lateral line present. Dorsal tin 

 inserted over or behind ventrals; caudal tin forked; no adipose fin; dor- 

 sal and anal depressible into a sheath of scales; pectorals and ventrals 

 each with a long accessory scale. Parietal bones meeting along top 

 of head. Pyloric coeca numerous. Species few, widely distributed 

 in the tropical seas. Numerous fossil forms are referred to this ancient 

 group, one of the oldest among bony fishes. The species are not much 

 valued as food, the flesh being dry and bony. 



KEY TO GENERA. 



Megalopin.e: 

 a. Pseudobranchite none; body oblong, covered with large scales; anal fin longer 

 than dorsal; last ray of dorsal j^roduced in a long filament. 



h. Dorsal fin inserted over or slightly behind ventrals Megalops, 1 



Elopin.e: 



au. Pseudobranchise large; body elongate, covered with small scales; 

 anal fin smaller than dorsal; last ray of dorsal not produced in a 

 filament Flops, 2 



