122 NORTHERN FISHES 



tiiiguish it from /. bubalus. In old specimens the nuchal region becomes 

 much swollen, but the back is not sharpened and farther back does not 

 become elevated. The depth of the body is contained 2.6 to 3.2 times 

 in the standard length, as opposed to 2.2 to 2.8 times (except in young 

 smaller than 80 mm.). This species further differs from /. niger, as 

 pointed out by Forbes and Richardson (1908 and 1920; 71-72). in 

 having a smaller eye, and a larger and less inferior mouth, with the 

 mandible less included. These differences may be indicated by a single 

 character index, a comparison of the greatest distance from mandib- 

 ular symphysis to the extreme end of maxillary with the length of 

 the orbit, between its free rims. In the larger young to smaller adults 

 this measurement is greater, usually much greater than the orbit in 

 niger, but less than or barely equal to the orbit in hubalus. In large 

 adults, the mouth measurement becomes somewhat greater than the 

 orbital length in hubalus, but at comparable sizes that measurement 

 is twice the orbit in niger. In young, about two to four inches long, the 

 mouth measurement in niger about equals the orbit, but in bitbahis- is 

 only a))out two-thirds the orbit." 



Separation of this species, Ictiobus niger, from the next species, 

 Ictiobiis biibalus, or even from Megastoniatobus cyyrinella, is some- 

 what difficult, for it is indeed a borderline form, and consequently at 

 present we are forced to restrict our report of its range to the Mississippi 

 River proper, where positive identifications have been made. 



The black buffalofish is said to be the largest of the buffalofishes, but 

 it is less common than the others. It has an elliptical and robust body. 

 The head is thick and heavy, with a blunt and broadly rounded snout. 

 The mouth is oblique. The lips are thin; the upper lip is faintly striated 

 and the lower lip coarsely striated. The level of the upper lip is about 

 halfway between the lower margin of the orbit and the chin. The dorsal 

 fin has from 29 to 30 rays. The scales are large, numbering 36-40 in the 

 lateral line. 



The normal color of this fish is much darker than that of the other 

 buffalofishes, but it is subject to much variation. Occasionally a red 

 phase occurs, causing some individuals to resemble giant goldfishes. 



The black buffalofish ranges from southern Minnesota to the Ohio 

 Valley and southwestward to Mexico. It occurs rarely in a number of 

 large streams and muddy lakes in southern Minnesota. In Wisconsin 

 Greene (1935) reported this fish only from Lake Pepin and from bayous 

 of the Mississippi River. 



SMALLMOUTH BUFFALOFISH (Razorback Buffalofish) 

 Ictiobus hubalus (Rafinesque) 



The smallmouth buffalofish has a compressed body with the back 

 considerably elevated. The head is small and more compressed and 



