()8 



Certain of the sunflshes evidently take plant food purposely, on occasion. 

 this making, for example, nearly a tenth of the food of forty-seven speci- 

 mens of Lepomis. Among the larger fishes, the principal vegetarian is 

 the gizzard shad, in w^hich this element was reckoned at about a third, — 

 taken, however, not separately, but with quantities of mud. A consider- 

 able part of it was distillery slops obtained near towns. 



The buffalo fishes are likewise largely vegetarian, more than a fourth of 

 their food coming from plants, — about a third of this in our specimens. 

 refuse from distilleries. N'egetation made a tenth of the food of the larger 

 genera of catflshes (Amiurusand Ictalurusj. — some of it distillery refuse. — 

 and nearly as large a ratio of that of the great Polyodon. 



T»Iot infrequently, terrestrial vegetable rubbish — seeds of grasses, leaves 

 of plants, and similar matter — was taken in quantity to make it certain 

 that its appro])riation was not accidental. 



Besides a great variety of Alga\ both filamentous and unicellular, in- 

 cluding considerable quantities of diatoms, the principal plant forms 

 found in the food of fishes were the duck-weeds Lemna and Wolttia. The 

 deep-bodied suckers, especially, occasionally take quantities of these little 

 plants during the autumnal months. 



MUD. 



The principal mud-eating fishes are the gizzard shad, the common shiner, 

 and the genera of minnows belonging to the groups with elongate intes- 

 tines and cultrate pharyngeal teeth: viz., Pimephales, ITybognathus, 

 Chrosomus, and Campostoma. Much mud was taken also by the cylindri- 

 cal members of the sucker family, but apparently as an incident to their 

 search for mollusks. 



Summary of the Food of the Young.* 



By an examination of three hundred and seven specimens, representing 

 twenty-seven species, twenty-six genera, and twelve families of Illinois 

 fishes, I learn that the food of many species dilfers greatly according to 

 age, and that, in fact, the life of most of our fishes divides into at least 

 two periods, and that of many into three, with respect to the kinds of 

 food chiefiy taken. 



In the first of these periods a remarkable similarity of food was noticed 

 among species whose later feeding hal)its are widely different. The full 

 grown black bass, for example, feeds principally on tishes and crayfishes, 

 the sheepshcad on mollusks, and the gizzaril shad on nuul and Alga-, 

 while the catfishes are nearly omnivorous: yet all these agree so closely in 

 food when very small, that one could not possibly tell from the contents 

 of the stomachs which group he was dealing \\\t\\. 



I will now summarize the facts concerning the earliest iood of the prin- 

 cipal species, taken fterlatiut: 



The food of six common perch (Porn hitca) from ;in iucli to an inch and 

 a quarter long, consisted wholly of Entomostraca i ninety-two per cent. > 

 and minute laiva^ of Chironomus, Xo very small white bass \LabracidaM 

 were found, the youngest being an incli and a quarter long. Half the food 

 of this consisted of Entomostraca. and tlie other half of minute gizzard 

 shad. Forty-three sunflshes (CentrarchicUe) from five-eighths of an inch to 



* For detailed treatment of this topic see Bull. 111. St. Lab. Nat. Hist.. Vol. I.. No. 3. p. 

 66, aiul No. 6. D. 95. 



