58 The Food of Fishes. 



per cent, of the food, and Entomostraca of the order 

 Ostracoda (Oyprids), twenty-six. As both these are found 

 most abundantly in muddy bottoms, it is evident that the 

 fish is, at least at first, a bottom feeder. Traces of mol- 

 lusks appear thus early, as well as a few Ephemerid larvae 

 (five per cent.). The remainder of the food was insects' 

 eggs and Daphnids, — chiefly Simocephalus americanus — 

 (twelve per cent.). Chydorus was found in five speci- 

 mens, but in too small quantity to figure in the averages. 

 Five specimens were studied between two and three 

 inches long. In these the same food characters continue, 

 modified somewhat by the introduction of larger objects. 

 The Ohironomus larvde stand at forty-four per cent., and 

 the Oyprids at eighteen per cent. Fourteen per cent, of 

 Allorchestes and eleven per cent, of Neuroptera larvae are 

 the only important elements remaining. Two per cent, of 

 young Unios were noticed. Nearly half of the food of two 

 larger specimens, between two and three inches long, con- 

 sisted of mollusks, — chiefly Physa. A few Chironomi 

 and about equal quantities of Ephemerid larvas and Allor- 

 chestes were all the remaining food. Entomostraca there- 

 fore disappear at this point. 



Food of the Adult. 



Forty-six per cent, of the food of the nine adults consisted 

 of Mollusca, including Planorbis, Amnicola and Valvata 

 tricar inata., and six per cent, of undetermined bivalves. 



The insect food was twenty per cent, of the whole, Crus- 

 tacea twenty-two per cent., and vegetaLtion twelve per cent. 

 Half of the last was Chara, and the remainder chiefly Myrio- 

 phyllum and Algse. The Crustacea were all Allorchestes 

 and Asellus. The insects included a trace of Chironomus 

 larvae and a few water-beetles (Hydrophilidae), and the 

 usual Neuroptera larvae, among which case-flies of the 

 genus Leptocerus were noticed. 



Not a trace of fishes was found in the stomachs of these 

 specimens ; and this fact, together with the large percent- 

 age of molluscan food, constituted the leading alimentary 

 peculiarities of the species. 



The first of these is doubtless related to the small mouth, 



