62 



VERTEBRATE ANIMALS OF THE UNITED STATES 



fo First ray of dorsal fin separate and joined with 

 the other rays by a membrane. 



gi Lateral line incomplete lo. Pimephales. 



g2 Lateral line complete 1 1. Hyborhynchus. 



a2 Digestive canal short, less than twice the length of the body; 

 peritoneum usually pale, 

 bi Teeth mostly blunt and enlarged, but slightly hooked; 

 large fishes on the Pacific Slope. 



Ci No barbels present 12. Mylopharodon. 



C2 Barbels present 13. Mylocheilus. 



bo Teeth slender, hooked; species mostly not on the Pacific 

 Slope. 

 Ci Teeth in main row 5-5 or 4-5. 



di Barbels present, often very small. 



ei Tail symmetrical; in the eastern and central 

 States. 



fi Dorsal fin without a black spot 14. Leucosomus. 



U Dorsal fin with a black spot 15. Semotilus. 



62 The upper lobe of tail longer than the lower; in 



California 16. Pogonichthys. 



d2 Barbels absent (except in Margariscus). 



ei Abdomen behind ventral fins rounded and scaled, 

 fi Teeth 2-rowed, usually with 2 teeth in the 

 lesser row. 

 gi Size very large, the length being up to 1,000 



mm 17. Ptychocheiliis. 



go Length not over 400 mm. 



hi Caudal peduncle very long and slender. . 18. Gila. 

 h.2 Caudal peduncle stout. 

 ii Lateral line complete. 



ji Mouth moderate in size; the Pacific 

 Slope and Rocky Mountain 

 region, 

 ki Anal fin with 7 or 8 rays; fins 

 low. 

 li Caudal peduncle very deep. .19. Siboma. 

 I2 Caudal peduncle not very 



deep 20. Tigoma 



k2 Anal fin with 9 to 22 rays; fins 



high 21. Cheonda. 



22. Richardsonius. 

 J2 Mouth very wide; lower jaw much 



projecting; Atlantic Slope 23. Clinostomus. 



\i Lateral line incomplete or wanting; 

 eastern and central States. 



ji Lateral line very short 24. Pfrille. 



J2 Lateral line more or less incom- 

 plete. 



