Introduction. lxi 



b. Ventral fins present, abdominal. PAGE 



c. Adipose fin on dorsal region present, 

 d. Body without scales; 4 to 8 long barbels 

 about the mouth and nostrils; a single 



spine in each pectoral and dorsal fin Siluridce 8 



dd. Body with scales, mouth without barbels; 

 pectoral and dorsal fin without spines, 

 e. Mouth large; teeth all conical ; body elon- 

 gate, depth sH to 5X; anal rays 10 to 12. . . .Salmonidce 95 

 ee. Mouth smaller; teeth incisor-like or else 

 rudimentary; body deep, compressed, 

 depth i% to 1%, anal rays more than 18. .Characinidce 83 

 cc. Dorsal region without adipose fin. 

 f. Tail heterocercal ; scales rhomboidal, very 



hard, ganoid Lepidosteidce 4 



ff. Tail not heterocercal; scales normal, thin. 

 g. Dorsal fin single, composed of soft rays 

 only. 

 h. Jaws toothless, head without scales, 

 i. Ventral region without bony serrae; body 

 elongate, not much compressed, 

 j . Mouth usually inferior ; lips thick, fleshy 

 with plicae or papillae ; pharyngeal teeth 

 very numerous, in a row like the teeth 

 of a comb; dorsal of more than 10 rays. . .Catostomidce 24 

 jj. Mouth usually terminal, lips thin, not 

 fleshy, without plicae or papillae; phar- 

 yngeal teeth few, fewer than 8 ; dorsal 

 fin with less than 10 rays (except in the 



car P) Cyprinidce 36 



ii. Ventral region with bony serrae, body 



deep, much compressed Dorosomatidce 92 



hh. Jaws with teeth ; head more or less scaly, 

 k. Lateral line wanting or represented by 

 a few imperfect pores; jaws not pro- 

 duced into a long beak Pceciliidce 98 



kk. Lateral line present, running as a fold 

 along side of belly; both jaws produced 



into a beak Belonida 1 60 



gg. Dorsal fins 2, the first composed of spines, 

 the second of soft rays. 

 1. Anal spines 3 ; dorsal spines strong, 4 Mugilidce 185 



