45 



contributes so largely to the food of other fishes, although it- 

 self of little or no direct advantage to mankind. I found this 

 family dividing into several groups based upon the length of 

 the intestine and the form of the pharyngeal teeth. In the first 

 of these groups, containing several of the more abundant sorts, 

 about three fourths of the food consisted of soft black mud, the 

 remainder being both animal and vegetable matter, chiefly the 

 latter. These fishes all had very long intestines and smooth 

 grinding teeth in the throat. In another group quantities of 

 mud are also taken, but with it many Entomostraca ; while in 

 groups three and four, containing by far the greater portion of 

 the family, the food is essentially different, about three fourths 

 of it being insects and small crustaceans, and the remainder 

 vegetation. I note especially here the value of the mud-eating 

 minnows as food for larger fishes, since while abundant and 

 easily maintained, they do not compete with the young of the 

 larger fishes to whose sustenance they may be applied. 



One of the most striking characteristics of the fish-fauna of 

 the Mississippi Valley is the prominence of the sucker family^ 

 several of which are among the most abundant of our larger 

 fishes. About one tenth the food of this family taken as a 

 whole consisted of vegetation, eaten chiefly by the buffalo fishes, 

 and in them composed largely of distillery slops. The family 

 is, however, essentially carnivorous, mollusks and insects 

 appearing in nearly equal ratio in the food. The former are 

 taken much the more generally by the cylindrical suckers, 

 and the latter about equally by all except the stone roller, which 

 collects great quantities of insect food by pushing about the 

 stones in running water. A large proportion of the insects 

 eaten are small larvae of gnats (Chironomus). Some of the 

 deeper-bodied species with long gill-rakers, especially the river 

 carp, feed largely on Entomostraca, this latter species swallow- 

 ing also considerable quantities of mud. 



The catjishes, taken together, are nearly omnivorous in habit, 

 and their feeding structures have a correspondingly general 

 character. The capacious mouth, wide gullet, and short, broad 

 stomach admit objects of large size and nearly every shape. 

 The jaws, each armed with a broad pad of fine, sharp teeth, are 



