444 Illinois State Laboratory of Natural History. 



MOXOSTOMA AUEEOLUM, LeS. RED HORSE. 



This species, less abundant in central Illinois than the 

 preceding, takes almost identical food, so far as one may judge 

 from the six specimens examined by me from Pekin, Peoria, 

 and Crystal Lake in northern Illinois. The food was practically 

 all animal, about one half of it Mollusca largely Vivipara 

 and Sphaerium. The insects were, as before, mostly Chironomus 

 larvae and pupae, the only other form worthy of note being 

 smooth, slender, distinctly segmented, footless larvae with 

 elongate brown heads very common in the food of fishes, but 

 not yet identified.* 



MlNYTREMA MELANOPS, Raf. STRIPED SUCKER ; SPOTTED MlJL- 

 LET. 



In this species, not uncommon throughout the State in 

 suitable streams, the alimentary structures are not essentially 

 different from those of Moxostoma, the pharyngeal teeth being, 

 however, more numerous and more closely set, about fifty- 

 five in the series, the lower five to ten enlarged, but less so 

 than in Moxostoma, and with the grinding surface less dis- 

 tinctly defined, most of even these largest teeth still presenting 

 a somewhat crenate margin. 



So far as indicated by the four specimens examined, the 

 food of this species is similar to that of the preceding, be- 

 ing nearly all Mollusca, differing, however, in the fact that 

 the thin-shelled bivalve Sphaerium had been taken in prefer- 

 ence to the thick-shelled univalves. A Cyclops and a larger 

 percentage of Cypris represented the Entomostraca. The small 

 ratio of insects noticed were all Chironomus larvae. 



CATOSTOMUS TERES, Mitch. COMMON SUCKER ; WHITE SUCKER ; 

 BROOK SUCKER ; FINE-SCALED SUCKER. 



Abundant northward, occurring rarely in the Illinois as far 

 south as Peoria, and still more rarely in the extreme southern 

 part of the State. Wherever abundant, it inhabits nearly all 

 waters, both lakes and flowing streams. It is common in Lake 

 Michigan. 



* This larva has the superficial characters of the Mycetophiliclie, 

 and was doubtfully assigned to that group by Dr. Williston, in a 

 recent letter to me. 



