1936] Schults: Keys to Fishes 117 



33b. Opercles complete ; origin of dorsal behind 

 base of pelvic fins ; gill rakers present and 

 long ; adipose fin absent. 

 Viper Fishes . .27. Gonostomidae, p. 142 



24b. Front of dorsal considerably behind middle of body. 

 32. Sudidae, p. 151 



21b. The anterior dorsal fin composed of spines connected by 

 membranes, the posterior dorsal fin composed of soft 

 rays ; no adipose fin present ; pectoral fins entire, the low- 

 er 5 to 8 rays not detached, not prolonged, and not fila- 

 mentous. 



34a. Teeth strong, canine-like, unequal ; lateral line pres- 

 ent ; branchiostegals 7. 

 Barracudas 50. Sphyraenidae, p. 160 



34b. Teeth weak ; lateral line absent ; branchiostegals 

 5 or 6. 

 Silversides 49. Atherinidae, p. 160 



20b. Dorsal fin single; no adipose fin and no photophore present. 



35a. Dorsal fin followed by a series of detached soft rays 

 or finlets. Fig. 11. 

 Sauries 37. Scomberesocidae, p. 154 



35b. Dorsal fin not followed by finlets, nor preceded by dis- 

 connected spines ; no adipose fin present. 



36a. Upper lobe of caudal fin much longer than lower 

 lobe and tail heterocercal ; body with large bony 

 plates, each with a sharp keel or spine. 

 Sturgeons 16. Acipenseridae, p. 133 



36b. Upper lobe of caudal fin not longer than lower and 

 tail homocercal ; body without plates as above. 



37a. Head with scales ; anal and dorsal fins placed 

 in the posterior 3rd of the body ; origin of dorsal 

 fin nearly over the origin of anal. 



38a. Lateral line present; jaws shaped much like a 

 duck's bill and prolonged; teeth strong. 

 Pikes or Pickerels 35. Esocidae, p. 152 



38b. Lateral line wanting; jaws normal and not pro- 

 longed; teeth not strong or canine-like. 

 Mud Minnows 36. Novumbridae, p. 152 



37b. Head without scales ; dorsal fin placed in middle 

 3rd of the body except in the Alepoceplialidae ; origin 

 of dorsal much in advance of anal origin, less so 

 in the Alcpocephalidae. 



39a. Branchiostegals 6 to 15; gill membranes not 

 joined to isthmus ; fig. 12. 



40a. No lateral line ; gill rakers long and slender. 



