70 FISHES OF ILLINOIS 



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, re- 

 taining objects large enough to serve as food, and to crush and 

 masticate 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 decurved and the lower elevated so that each gill forms 

 about three fourths of a circle. There are seventy-five gill- 

 rakers in the anterior row, the longer of which are fully equal in 

 length to the corresponding 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, 

 consisted 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 Chironomus larvae and larvae 

 of day-flies. 



The species breeds in earlv 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 



(Pl, p. 71; Map X) 



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



J. & G. (Bubalichthys), 116; M. V., 44; J. & E., I, 164; 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 



