70 The Food of Fishes. 



cies seeks its food from the first upon the bottom. In a 

 specimen two inches long, the Chironomus larvae fell to 

 fifteen per cent, while the Palingenia larvae rose to eighty 

 per cent., and other Ephemerids and Cyclops made up the 

 remainder of the food. 



Four specimens, also from the Ohio, at Cairo, from two 

 to four inches long, were found to have recently fed upon 

 Ephemerid larvae and larvae of aquatic beetles, Gyrinidse 

 and Hydrophilidae, in about equal quantities. Only five 

 per cent, of their food was Chironomus. 



Sixteen individuals of medium size were taken from the 

 Illinois and Ohio rivers, in April, June, September and 

 October of four different years. There was nothing in the 

 contents of these stomachs to indicate any difference in 

 food resulting from these differences of date and situation. 

 The food, on the contrary, was remarkably simple and 

 uniform, consisting chiefly of the larvae of Neuroptera 

 (eighty-four per cent.), of which Palingenia hilineata 

 formed altogether the most important part (seventy-six 

 per cent.), — the remaining eight per cent, being dragon- 

 flies. A single small sucker (Catostomidae), a few mol- 

 lusks (Planorbis, young Unios and thin-shelled Anodon- 

 tas), and some Aselli complete the brief dietary of this 

 group. 



It is not until we examine the food of full-grown speci- 

 mens that we wholly appreciate the utility of the enor- 

 mous crushing pharyngeal jaws with their pavement teeth, 

 found in this species. The entire food of the three large 

 specimens examined, taken at Peoria, in April and Octo- 

 ber, proved to consist of mollusks only, including forty-six 

 per cent, of the thick and heavy water snail, Melantho 

 decisa^ whose shell probably no other fish in our rivers 

 could break. Cyclas, Anodonta and indeterminable Gas- 

 teropoda composed the remainder of the food. 



