Food Belations of Fresh-Wafer FisJies. 477 



account the necessities of the species whose increase is desired, 

 through all ages and all stages of their growth, at every season 

 of the year, and under all varieties of condition likely to 

 arise. We should derive, in short, from these and similar re- 

 searches, a body of full, precise, and significant knowledge to 

 take the place of the guess-work and empiricism upon which 

 we must otherwise depend as the basis of our efforts to main- 

 tain the supply of food and the incitement to healthful recrea- 

 tion afforded by the waters of the State. 



As a contribution to the general suJoject, I present herewith 

 a summary account of the food of twelve hundred and twenty- 

 one fishes obtained from the waters of Illinois at intervals from 

 1876 to 1887, and in various months from April to November, 

 These fishes belonged to eighty-seven species of sixty-three 

 genera and twenty-five families. They were derived from 

 waters of every description, ranging from Lake Michigan to 

 weedy stagnant ponds and temporary pools, and from the Mis- 

 sissippi and Ohio Rivers to the muddy prairie creeks, and the 

 rocky rivulets of the hilly portions of the State. Nine hundred 

 and fourteen of the examples studied were practically adult, so 

 far as the purposes of this investigation are concerned, the 

 remaining three hundred and seven being young, in the first 

 stage of their food and feeding habits. More than half these 

 young belonged to a single species, — the common lake white- 

 fish, — but the remainder were well distributed. 



I have arranged the matter under the following general 

 heads: (1) a summary statement of the food, so made as to 

 exhibit (a) the kinds and relative importance of the principal 

 competitions among fishes and {h) the relative value to the prin- 

 cipal species of fishes of the major elements of their food; (2) a 

 brief account of the food of the young; (3) an examination of 

 the permanency and definiteness of distinctions with respect to 

 food, between different species, and also between higher groups; 

 (4) a review of the structures of fishes related to food prehen- 

 sion and to their feeding habits; and, finally, (5) a classified 

 list of the objects detected in the food of fishes, with a state- 

 ment, against each object, of the species feeding on it and the 

 number of specimens in which it was found. 



