TJte Food of Fresh- Water Fishes. 449 



commonly shipped from the Illinois and Mississippi under the 

 name of buffalo fish. They all sell as "coarse fish," but from 

 their abundance and their fair character as food, are, on the 

 whole, the most important commercial fishes in our streams. 



The gills of this species are very compactly disposed in a 

 rather small branchial chamber, the upper ends of the arches 

 being decurved and the lower elevated so that each gill forms 

 about three fourths of a circle. Ten of the lower rakers of the 

 anterior series are reduced to thickened ridges which extend 

 obliquely across the horizontal portion of the arch. The re- 

 mainder of this series, thirty-five in number, are flattened, 

 minutely toothed, the central ones about as long as the cor- 

 responding filaments of the gill, the others regularly shortened 

 above and below. The other rakers are similar to those of 

 Moxostoma, having the form of toothed triangular plates, with 

 their apices slightly projecting beyond the opposed surfaces of 

 the arches. The interlocking tips are a little more prominent 

 than in Moxostoma, and the whole apparatus is somewhat bet- 

 ter developed. 



The pharyngeal bones are moderately heavy, triangular in 

 section, about as thick as high ; and the teeth, about one hun- 

 dred and thirty upon each jaw, project directly backwards and 

 act, as in Moxostoma, against a semi-circular rim of cartilage. 

 They are compressed, and more or less crenate on the cutting 

 margin, the upper ones minute, the others gradually thicken- 

 ing downwards so that the lower twelve occupy about one 

 fourth of the length of the arch. The edges of these lower 

 teeth are rounded, not acute. 



Seventeen specimens of this species, distributed in seven 

 lots, collected from the central course of the Illinois River and 

 from the Mississippi at Quincy in the years 1880, 1882, and 

 1887, and in various months from April to October, give the 

 following general view of the food. 



In decided contrast to the preceding members of the family, 

 about one fifth of the food consisted of vegetation taken by 

 sixteen of the fishes nearly all aquatic, but with an occasional 

 admixture of terrestrial rubbish. The principal vegetable ele- 

 ment was a small duckweed ( Wolffia) especially abundant in 

 fishes taken from the Illinois during the autumn of 1887, 



