ICTIOBUS 



71 



FIG. 15 



when taken from clear water; all fins dark. Head thick and heavy, its 



length 3.7 to 4, depth 4 to 4.8, width 4.9 to 5.6 in length of body; snout very 



blunt and broadly rounded, its profile continuous with that of frontal region; 



interorbital space 2 to 2.3 in head; mouth moderate, considerably smaller 



than in last species, and but slightly larger than in next species, subterminal, 



protractile forward and downward, 



as a rule but little oblique, the edge 



of the mandible falling considerably 



below median axis, level of upper lip 



about midway between chin and 



lower margin of orbit ; angle formed 



by articulation of mandible 



with quadrate evident, but less 



prominent than in cyprinella; lips 



rather thin, but less so than in last 



species, the upper faintly, the lower 



rather coarsely, striated; eye 5.1 to 



6.6 in head, situated well upward 



and forward; opercles not so broad 



as in the last. Dorsal rays 29 or 30, 



the longest considerably less than 



^ base of fin; other fins about as 



in the preceding species, the caudal 



not quite so deeply forked. Scales 7 or 8, 36-40, 6 to 8; lateral line complete, 



less flexuose posteriorly and not so abruptly elevated in front of dorsal as 



in cyprinella. 



Spring males without tubercles. 



The mongrel buffalo appears to vary somewhat more than 

 either I. cyprinella or bubalus, but we have met with no cases 

 which appear to show intergradation with either. This species 

 seems to be always distinguishable from the former by its much 

 smaller and less oblique mouth, the upper lip falling far below 

 the level of the lower margin of the orbit, and by the coarsely 

 striate lower lips; from the latter by the more elongate and less 

 compressed body, and by the broad rounding of the frontal 

 region and of the back in front of the dorsal fin. 



Distributed throughout the Mississippi Valley practically 

 as the red-mouth is, but less abundantly. 



This is a large species, sometimes exceeding 50 pounds in 

 weight, though commonly less than 20. It resembles the red- 

 mouth in habits and value. 



The same may be said with respect to its food, our 17 speci- 

 mens, well distributed as to time and place of capture, having 

 taken ratios of animal and vegetable food almost identical with 

 those of cyprinella 67 per cent, and 33 per cent, respectively. 

 There was a larger ratio of mollusks and of insects the latter 



