FISHES OB" MINNESOTA 27 



KEY TO THE GENERA OF CYPRINIDJ:. 



A. Intestine very long and wound many times around the air- 



bladdei Gampostoma, 28 



AA. Intestine not wound around the air-bladder; air-bladder in the 

 upper portion of the abdominal cavity. 



B. Digestive canal long, usually more than twice the length 



of the body; inside coat of the abdominal wall usually 



black; pharyngeal teeth one rowed, the grinding surface 



well developed. 



C. Pharyngeal teeth 5-5 or 4-5; dorsal fin inserted behind 



the ventrals; scales very small ; lateral line incomplete. 



Chrosomus, 28 

 CC. Pharyngeal teeth 4-4; dorsal fin inserted over the 

 ventrals; scales rather large. 

 D. Less than 15 scales before the dorsal fin; the first 

 (rudimentary) ray of the dorsal fin firmly joined 

 to the next. .... Hybognathus, 28 



DD. More than 20 scales before the dorsal fin; first 

 ray of the dorsal blunt and not firmly joined to 

 the second but connected with it by a membrane. 



Pimephales, 29 

 BB. Digestive canal short, less than twice the length of the 

 body; inside coat of the abdominal wall generally of pale 

 coloration. 

 C. Pharyngeal teeth in the main row 5-5 or 4-5. 



D. Abdomen behind the ventral fins not compressed 

 into a sharp edge but rounded, the scales pass- 

 ing over it. 

 E. Maxillary bones ending in a small barbel; 



premaxillaries protractile. . . Semotilus, 30 

 EE. Maxillary without a barbel; pharyngeal teeth 

 two rowed and usually two teeth in the 

 inner row, teeth strongly hooked; scales 



small Leuciscus, 30 



DD. Abdomen compressed to a sharp ridge so that the 

 scales do not pass over it; rays in the anal fin 12 

 to 18; lateral line much decurved. . . Abramis, 32 

 CC. Pharyngeal teeth in the main row 4-4. 



D. Maxillary bonc not ending in a barbel; upper 



jaw protractile; scales large, 30-50. . iXotropis, 331 

 DD. Maxillary with a barbel, though small. 



E. Scales small, 60 or more in the lateral line, 

 premaxillaries not protractile; teeth 2, 4-4, 2. 



Khinichtbys, 38 

 EE. Scales large, 35 to 55; premaxillaries protract- 

 ile, teeth 4-4 or 1, 4-4, 1 or 0. . Hybopsis, 40 



