228 Field Museum of Natural History — Zoology, Vol. VII. 



g. Pectoral fins each with a strong spine; head with more than 

 4 barbels; body without scales. SiluridcB, 240 



gg. Pectoral fins each without a strong spine ; head usually without 

 barbels, but when present never more than 4; body usually with 

 scales. 



h. Ventral fins without spines, or with one spine and one soft ray; 

 anterior dorsal fin if composed of spines only, these not con- 

 nected by a membrane. 



i. Scales if present cycloid, their free edges smooth. 



j. Body with true scales or linear embedded ones; ventral fins, 

 when present, with more than 5 soft rays; no disconnected 

 dorsal spines. 



k. Head without scales. 



I. No dorsal adipose fin present. 



m. Ventral surface not armed with bony serrae; lateral line present, 

 n. Teeth not present in jaws; anal fin short of less than 15 rays, 

 o. Dorsal fin with more than 10 rays; mouth usually inferior with 



thick fleshy lips, with plicae or papillae; pharyngeal teeth in a 



single row, more than 10. CatostomidcB, 248 



00. Dorsal fin of fewer than 10 rays; mouth usually terminal, with 



thin lips without plicae or papillae; pharyngeal teeth in one or 



two rows, fewer than 9. Cyprinidce, 257 



nn. Teeth present in jaws; anal fin long, of more than 20 rays. 

 p. Body long and slender, eel-shaped; dorsal and anal fins long 



and continuous with the caudal ; scales minute, linear. 



AnguillidcB, 284 

 pp. Body deep, compressed, not eel-shaped; dorsal and anal fins not 



continuous with the caudal; scales large. HiodontidcB, 285 



mm. Ventral surface armed with bony serrae ; lateral line wanting, 

 q. Dorsal fin with its last ray produced into a long filament; jaws 



without teeth ; maxillary not in 3 pieces. DorosomidcB, 287 



qq. Dorsal fin with its last ray not produced into a long filament; 



jaws with weak teeth; maxillary in 3 pieces. Clupeidcs, 288 



II. Dorsal adipose fin present. SalmonidcB, 289 

 kk. Head more or less covered with scales. 



r. Jaws long, with large canine-like teeth; lateral line present. 



EsocidcB, 295 

 rr. Jaws short, without canine-like teeth; lateral line wanting, or 



nearly so. 

 s. Upper jaw not protractile. UmbridcF, 297 



ss. Upper jaw protractile. PoPciliidcE, 298 



