CTPEINID.E.— ICTIOBCJS. 14 



<j 



§ Intestine elongate, with several convolutions ; pharyngeal teeth compressed, 

 scarcely hooked, with broad grinding-surface, in a single series, 4 — 4. 



Scales large, less than 60 in a longitudinal series 7. Hybognathus. 



Scales small, 60 or more iu a longitudinal series 8. Algansea. 



§§ Intestine comparatively short; pharyngeal teeth sub- 

 conical, scarcely hooked, wide apart, in 2 series, 



5, 2 — 2, 1 9. Ptvchocheilus. 



§ § § Intestine comparatively short ; pharyngeal teeth compressed and hooked, 

 without or with narrow grinding-surface, not set wide apart. 

 t Pharyngeal teeth in 2 series, 4-6, 1-2—2-1, 4-6 . 10. Leuciscus. 

 %X Pharyngeal teeth usually in a single series, 4 — 4; sometimes a second 

 series of 1 or 2 small teeth. 

 Lips normal ; scales rather large, 45 to 50 in a longitudinal series ; ventral 



fins 10-rayed 11. Falcula. 



Lips normal ; scales rather large, 30 to 60 in a longitudinal series; ventral 



fins 8-rayed 12. Notropis. 



Lips normal ; scales small, 85 to 95 iu a longitudinal series 13. Evarra. 



Lower lip forming a fleshy lobe on each side 14. Phenacobius. 



tt Gill-rakers very long, slender, and numerous . . .15. Xystrosus. 

 ** Pharyngeal teeth cylindrical, with obtusely convex apices, 



in a single series, 3 in number ou each side .... 16. Stypodon. 



b. First dorsal ray more or less enlarged and spinous or surrounded by thick skin, 

 separated by a membrane from the second ray. 



Jaws without hard sheaths 17. Pimephales. 



Jaws with hard sheaths, forming cutting-plates 18. Cochlognathus. 



B. A small barbel at or near the end of each maxillary. 



1. Mouth terminal, oblique. 



Scales rather large, 45 to 50 in a longitudinal series 19. Yuriria. 



Scales smaller, 55 to 75 in a longitudinal series 20. Couesius. 



2. Mouth subterminal or inferior. 



a. Praemaxillaries protractile. 



Scales large, less than 60 in a longitudinal series 21. Hybopsis. 



Scales smaller, 60 to 90 in a longitudinal series 22. Agosia. 



b. Prffimaxillaries not protractile 23. Rhinichthys. 



1. ICTIOBUS, Rafin., 1820. 

 Ictiobus and Carpiodes (Rafin.), Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, pp. 163, 165. 



This genus is at once distinguished from other Mexican Catostominte by the 

 elongate dorsal fin. It comprises about ten species, ranging from the region of 

 the Great Lakes to Guatemala. 



