196 CLASSIFICATION OF FISHES_, ETC. 



Ariosoma. Spiracle before the base of the pectoral ; nostrils simple. 

 Ophisurus. Dorsal and anal fin extending to the tip of the tail. 

 Leptognathus. Jaws and teeth long, acuminated ; end of the tail naked. 

 Pterurus. Dorsal, anal, and caudal fins distinct. 



MuR^NA. Pectoral fins obsolete, or none. 



Nettastoma. Jaws greatly elongated ; spiracles two, transverse. 

 Pachiurus. Pectoral fins minute, obsolete ; tail very thick, obtuse. 

 Murcsna. Pectorals none ; tail pointed ; spiracles on the sides of the 



head. 



Dalophis. Spiracles two, placed on the sides of the throat ; no pec- 

 torals. 



Ophiognathus. Dorsal and anal united ; no caudal ; pecto- 

 rals very small. 



IcHTHYOPHis. Eyes distinct ; teeth acute ; no fins whatever. 

 Alabes. Spiracle single ; pectorals large ; a concave disk 

 beneath. 



Family 2. SYNBRANCHID^. 



Spiracles placed under the throat. 



Sphagebran'chus. Spiracles two, approximate ; upper jaw 

 pointed. 



MoNOPTERUS. Spiracles two, united in a transverse cleft. 



Stxbranchus. Spiracle single ; dorsal, caudal, and anal fins 



united. 

 Ophicthys. Spiracle single ; body cylindrical ; no fins. 



Family 3. STERNARCHID^. 



Gymnotus. Body eel-shaped ; anal very long ; dorsal fin 

 wanting. 



Gymnarchus. Body scaly ; dorsal fin very long ; anal wanting. 



Carapus. Body much compressed ; dorsal, caudal, and anal 

 fins united. 



Sternarchus. Operculum concealed ; body scaly ; anal fin 

 distinct. 



Leptocephalus. Very thin, hyaline ; dorsal, anal, and caudal 

 fins united. 



FAiULY 4. PETROMYZONIDyE. 

 Eyes small, or none ; mouth longitudinal. 



Amphioxus. Lanceolate, hyaline ; no pectoral, dorsal, anal, 

 or caudal fins. 



