Order iv. Plectospondyli. 



THE CARP-LIKE FISHES. 



The anterior vertebrae modified as in the preceding order; oper- 

 cular bones all present; maxillary developed, not entering into the 

 base of a barbel; body covered with ordinary scales, rarely naked; 

 ventral fins abdominal. 



KEY TO THE FAMILIES OF PLECTOSPONDYLI. 



a. Braincase produced between the orbits; jaws PAGE 



toothless ; no adipose dorsal fin ; lower pharyn- 

 geal b.ones falciform. 



b. Pharyngeal teeth numerous, pectinate; max- 

 illary forming part of the margin of the upper 



jaw . '. C ' atostomidce 24 



bb. Pharyngeal teeth few; margin of the upper 



jaw formed by the premaxillaries only Cyprinidce 36 



aa. Braincase not produced between the orbits; 

 jaws usually with teeth; adipose fin usually 

 present Characinida 83 



Family IV. Catostomidae. 



THE SUCKERS. 



Body oblong or elongate, usually more or less compressed; head 

 more or less conical; mouth usually protractile and with fleshy lips; 

 margin of the upper jaw formed in the middle by the small premaxil- 

 laries and outside by the maxillaries ; jaws toothless; lower pharyn- 

 geal bones falciform, armed with a single row of numerous comb- 

 like teeth ; branchiostegals 3 ; gill membranes more or less united to 

 the isthmus ; gills 4 ; pseudobranchiae present ; scales cycloid ; lateral 

 line usually present; ventrals abdominal; alimentary canal long; no 

 pyloric cceca; air bladder in two or three parts. Fishes inhabiting 

 the fresh waters of Eastern Asia and North America. The buffalo 

 fishes are much used for food, but the other members of the family 

 are of little value for this purpose. 



KEY TO THE GENERA OF CATOSTOMID^E. 



a. Dorsal fin elongate, with 25 to 50 rays, its PAGE 



first 6 or 8 rays much longer than the others Carpiodes 25 



aa. Dorsal fin short, with 10 to 18 rays. 



24 



