Fooil Relations of Fresh-Wafer Fishes. -491 



ble average in the food of thirty-three specimens being seven- 

 teen per cent. Plant structures made about one fourth the 

 food of seven sticklebacks. 



Certain of the sunfishes evidently take plant food pur- 

 posely, on occasion, this making, for example, nearly a tenth 

 of the food of forty-seven specimens of Lepomis. Among the 

 larger fishes, the principal vegetarian is the gizzard shad, in 

 which this eleoaent was reckoned at about a third, — taken, 

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

 siderable 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. Vege- 

 tation made a tenth of the food of the larger genera of cat- 

 fishes (Amiurusand Ictalurus), — some of it distillery refuse, — 

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



Not infrequently, terrestrial vegetable rubbish — seeds of 

 grasses, leaves of plants, and similar matter — was taken in 

 quantity to make it certain that its appropriation was not acci- 

 dental. 



Besides a great variety of Alga3, both filamentous and uni- 

 cellular, including considerable quantities of diatoms, the prin- 

 cipal plant forms found in the food of fishes were the duck- 

 weeds Lemna and Wolfiia. 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 sliad, the 

 common shiner, and the genera of minnows belonging to the 

 groups with elongate intestines and cultrate pharyngeal teeth; 

 viz., Pimephales, Hybognathus, Chrosomus, and Campostoma. 

 Much mud was taken also by the cylindrical members of the 

 sucker family, but apparently as an incident to their search for 

 mollusks. 



