70 FISHES OF ILLINOIS 



it grows to a large size, sometimes reaching a weight of 50 pounds. 

 Although its flesh is of poor quality, it is used everywhere as food. 



Its structures of food prehension and appropriation — the 

 mouth, the gill-rakers, and the pharyngeal jaws and teeth — are 

 so constructed as to enable it to collect its food readily from a 

 muddy bottom, to strain away the greater part of the mud, retain- 

 ing objects large enough to serve as food, and to crush and masti- 

 cate hard or shell-covered objects, unfit for digestion entire. Its 

 pharyngeal jaws are not so strong as those of bubalus, the thickness 

 being about a fourth the depth. The teeth are some seventy-five 

 in number on each jaw, minute above, gradually but not greatly 

 •thickened below, the ten lowest occupying nearly a fifth of the 

 length of the arch. The gills are compactly disposed in a rather 

 small branchial chamber, the upper ends of the arches being de- 

 curved and the lower elevated so that each gill forms about three 

 fourths of a circle. There are seventy-five gill-rakers in the an- 

 terior row, the longer of which are fully equal in length to the cor- 

 responding gill-filaments, and eight or ten of the lower rakers are 

 fused in the form of thick oblique ridges. 



About a third of the food of seventeen specimens examined, con- 

 sisted of algae, seeds of aquatic plants, and ^distillery slops, the last 

 obtained off the Peoria city front where the wastes from distilleries 

 were emptied into the stream. Of the remaining two thirds, nearly 

 half consisted of Entomostraca, and more than half of aquatic insects, 

 very largely Chircmomus larva? and larvae of day-flies. 



The species breeds in early spring, ordinarily between the 10th 

 and 20th of April (Capt. Schulte). In 1898 the red-mouth spawned 

 between the 15th and the 30th of that month. 



ICTIOBUS URUS (Agassiz) 

 (mongrel buffalo; round buffalo) 



Agassiz, 1854, Amer. J. Sci. Arts (Silliman's Journal), XVII, 355 (Carpiodes). 



J. & G. (Bubalichthys), 116; M. V., 44; J. & £., I, 164j N., 50 (Bubalichthys niger); 



J., 65 (Bubalichthys); F., 82; F. F., I. 2, 81 (Bubalichthys niger), II. 7, 452; L., 



11. 



Body robust, elliptical, the dorsal and ventral outlines nearly equally 

 curved, the general form being much as in cyprinella except that the body 

 is somewhat more elongate and the back more broadly rounded in front 

 of dorsal; depth 3 to 3.4 in length. Size large, about as in last species. 

 Color usually darker than in cyprinella, a dark slaty gray, shading to 

 almost black when taken from clear water; all fins dark. Head thick 



