160 



commonly captured were larvjie of Gyrinidre and Hydrophilid.ne; whereas 

 the adult surface beetles themselves {Gyrinus, Dineutes, etc.), whose 

 zigzag-darting swarms no one can have failed to notice, were not once 

 encountered iu my studies. 



"The almost equally well known slender Water-skippers {Hijgrotre- 

 elms) seem also completely jjrotected by their habits and activity 

 from capture by fishes, only a single specimen occurring iu the food of 

 all my specimens. Indeed the true Water-bugs (Hemiptera) were gen- 

 erally rare, with the exception of the small soft-bodied genus Corisa, 

 which was taken by one hundred and ten sj^ecimens, belonging to 

 twenty-seven species, most abundantly by the Sunfishes and Top Min- 

 nows. 



" From the order Neuroptera fishes draw a larger part of their food 

 than from any other single group. In fact, nearly a fifth of the entire 

 amount of food consumed by all the adult fishes examined by me con- 

 sisted of aquatic larvae of this order, the greater part of them larvie of 

 Day Flies (Ephemeridse), principally of the genus Hexagenia.^ These 

 Neuropterous larva? were eaten especially by the Miller's Thumb, the 

 Sheei)shead, the White and Striped Bass, the common Perch, thirteen 

 species of the Darters, both the Black Bass, seven of the Sunfishes, 

 the Rock Bass and the Croppies, the Pirate Perch, the Brook Silver- 

 sides, the Sticklebacks, the Mud Minnow, the Top Minnows, the Giz- 

 zard Shad, the Toothed Herring, twelve species each of the true Min- 

 now family, and of the Suckers and Buffalo, five Oatfishes, the Dog- 

 fish, and the Shovel Fish— seventy species out of the eighty seven 

 which I have studied. 



"Among the above I found them the most important food of the 

 White Bass, the Toothed Herring, the Shovel Fish (51 per cent.), and 

 the Cropi^ies ; while they made a fourth or more of the alimentary con- 

 tents ot the Sheepshead (40 per cent.), the Darters, the Pirate Perch, 

 the common Sunfishes {Lepomis and Chamobryttus), the Eock Bass, the 

 Little Pickerel, and the common Sucker (36 per cent.). 



" Ephemerid larvte were eaten by two hundred and thirteen speci- 

 mens of forty-eight species, not counting young. The larvae of Hexa- 

 genia, one of the commonest of the 'River Flies,' was by far the most 

 important insect of this group, this alone amounting to about half of 

 all the Neuroptera e.aten. They made nearly one-half of the food of 

 the Shovel Fish, more than one-tenth that of the Sunfishes, and the 

 principal food resource of half-grown Sheepshead ; but were rarely 

 taken by the Sucker family, and made only 5 per cent, of the food of 

 the Catfish group. 



" The various larva^ of the Dragon Flies, on the other hand, were 

 much less frequently encountered. They seemed to be most abundant 

 in the food of the Grass Pickerel (25 per cent.), and next to that in the 

 Croppie, the Pirate Perch, and the common Perch (10 to 13 per cent.). 



'The winged adults of this and related genera are often called "Kiver Flies'' in. 

 Illinois. 



