494 Illinois State Lahoratoi-ij of Natural History. 



A dozen specimens of small gizzard shad, ranging in length 

 from four fifths of an inch to nearly two inches, had eaten 

 about ninety per cent, of Entomostraca, two per cent, of 

 Chironomus larvae, and, for the remainder, Alga?. 



The true minnows (Cyprinida?) seem to agree with the 

 suckers in the more minute character of their early food. Six 

 examples — three eights to three fourths of an inch long — too 

 small to determine, but apparently belonging to the genera 

 Minnilus, had eaten Entomostraca, Chironomus larvae, many 

 Protozoa, and unicellular Algae, a few filamentous Algae and 

 minute fungi and fungus spores, a water mite, and a few acci- 

 dental insects. In several specimens of the common chub min- 

 now (Semotilus), from five eighths of an inch to an inch in 

 length, seven per cent, of the food was Entomostraca, and the 

 remainder consisted of filamentous Alga?. It should be noted, 

 however, that twenty per cent, of that of the smallest speci- 

 men, which was five eighths of an inch long, was Cyclops, and 

 it may be that Semotilus lives wholly on Entomostraca at first, 

 merely changing its habit earlier than most of its allies. Two 

 other minnows of the genus Notropis, an inch and a half in 

 length, had eaten nothing but Entomostraca. The Cyprinida^, 

 like the sucker family, are toothless when young. 



Thirty young suckers were studied, representing five 

 genera of their family. The very smallest were found feed- 

 ing on Entomostraca only, and it is possible that these usually 

 form the first food of the family; but later they resort to 

 elements still more minute; viz., rotifers. Protozoa, and uni- 

 cellular Alga?, quantities of which were found in the intestines 

 of young suckers six inches or more in length. Young stone 

 rollers (Hypentelium) not more than an inch and a half long, 

 had taken chiefly larvae of Chironomus (ninety per cent.), the 

 remaining tenth being principally Entomostraca. A single 

 small black sucker (Minytrema) had eaten little but Cyclops. 

 Four chub suckers (Erimyzon), two three quarters of an inch, 

 and two an inch and a quarter long, had eaten only Entomos- 

 traca and a trace of water mites. In two larger specimens, 

 however, still minuter forms were the leading feature of the 

 food, including rotifers. Protozoa, and unicellular Algae. An- 

 other example, three inches long, had eaten a trace of 



