84 The Food of the Smaller Fresh - Water Fishes. 



Hybopsjs stramineus, Cope. Stkaw-colored Minnow. 



This insignificant species has been found by us in rivers and 

 small streams throughout the State. 



The mll-rakers were few and short. 



Only five specimens were studied, all from rivers in Central 

 Illinois. About three-fourths of their food consisted of animal 

 matter, nearly all neuropterous larva? (fifty-eight per cent.), 

 EphemeridiT? standing at forty-eight per cent., and case-worms at 

 ten. Crustacea were ten per cent., all Cyclops except a trace of 

 Canthocamptus. About one-fourth of the food was vegetation, 

 chiefly seeds of grasses, occurring, of course, only accidentally in 

 the water. Two had derived from ninety to one hundred per cent, 

 of their food from ephemerid larva?, and four of the five had eaten 

 vegetation amounting to as much as eighty per cent. 



LuxiLUS coRNUTus, Raf. Shiner. 



This large and fine minnow is probably the commonest fish in 

 Illinois, occurring in lakes and streams of all sizes everywhere 

 throughout our limits. 



The gill-rakers are short and few, and of insignificant develop- 

 ment, and the intestine is shorter than the head and body. 



Twenty-one specimens were studied, from all parts of the 

 State and at various seasons of the year. Animal food amounted 

 to two-thirds of the whole, fourteen per cent, being fishes, eaten, 

 however, by only one of the specimens. Insects, eaten by 

 nineteen, were reckoned at forty-five per cent., only one-fourth of 

 them terrestrial. Gyrinid larvfe, Corixa, and larva? of I^aMngenia 

 bilineata were among the forms recognized. The crustacean 

 ratio was insignificant, standing at only three per cent., all the 

 abundant amphipod, Allorchestes dentata^ with the exception of 

 traces of a considerable variety of Entomostraca, including 

 Chydorus, Acroperus leucocephalus, and Cypris. One of the 

 water- worms (Lumbriculus) was noticed in a single specimen. 

 Vegetable food was reckoned at thirty-eight per cent., only about 

 one-third of it consisting of Alga?, and the rest of accidental 

 fragments, including the seeds, anthers, and pollen of plants, with 

 a little Potamogeton and various forms of fungus spores. One of 

 the commonest of the Algje was Cladophora glomerata^ taken 



*Kindly determined for me by Rev. Francis Wolle, Bethlehem, Pa. 



