KEY TO FAMILIES. 1 7 



Class : PISCES. 



Sub- Class: TELEOSTOMi (True Fishes). 



Artificial Key to the Families of Fishes. 

 I. Ventral Fins Present — Abdominal. 



A. Back with an adipose fin behind the single, rayed dorsal fin. 



B. Head with barbels about mouth and nostrils, body scaleless ; a single spine in 



each pectoral and in dorsal fin. — Silurid^e. 



BB. Head without barbels ; body scaled. 



C. Dorsal, anal and ventral fins each with a small but distinct spine ; scales 



ctenoid.— Percopsid.e. 



CC. Dorsal, anal, and ventrals without distinct spine ; scales not ctenoid. — 



SALMONID.E. 



AA. Back without adipose fin. 



D. Dorsal fin single, composed of rays, and not preceded by a series of free spines. 

 E. Tail evidently strongly heterocercal. 



F. Body naked ; snout with a spatulate blade ; mouth wide, without 



bartels.— Polyodontid.=e. 



FF. Body with scales or bony plates or shields. 



G. Body with 5 series of bony shields ; mouth inferior, tooth- 

 less, preceded by four barbels.— Acipenserid-e. 

 GG. Body scaly. 



H. Scales cycloid ; a broad, bony, gular plate ; dorsal fin 



many ra}-ed. — Amiid^e. 



HH. Scales ganoid ; no gular plate ; dorsal fin short. — 



Lepisosteid^e. 

 EE. Tail not evidently heterocercal. 



I. Gill membranes broadly joined to the isthmus ; head naked ; no 



teeth in jaws. 

 J. Lower pharyngeal teeth very numerous, in one row like the 



teeth of a comb.— Catostomid.e. 



J J. Lower pharyngeal teeth few, fewer than 8, in 1 to 3 rows. — 



Cyprinid^e. 



II. Gill membranes free, not attached to the isthmus. 

 K. Head scaly, more or less. 



L- Upper jaw not protractile, its lateral margins formed by 

 the maxillaries. 

 M. Jaws depressed, prolonged ; lateral line present. — 



Luciid^e. 

 MM. Jaws short ; no lateral line. — Umbrid/E. 



LI,- Upper jaw protractile, its margin formed by premaxil- 

 laries alone ; no lateral line. — Poeciliid-e. 



KK, Head naked. 



N. Lateral line well developed ; mouth large, teeth all 



pointed, some of them canine. — Hiodontid^e. 



NN. Lateral line wanting. 



O. Mouth small, inferior, toothless; stomach gizzard- 

 like. — DOROSOMATID.E. 



OO. Mouth moderate, terminal; stomach not gizzard- 

 like.— Clupeid^, 



