90 The Food of the Smaller Fresh - Water Fishes. 



Summary fok the Gkoui\ 



Ninety-five specimens of Group IV examined, representing 

 five crenera, had derived about three-fourths of their food from the 

 animal kingdom,, three per cent, of it being fishes, sixty-one per 

 cent, insects, one per cent. Arachnida, and eleven per cent. Crusta- 

 cea. One-third of the insects and spiders belong to terrestrial 

 species. Chironomus larvji? are among the most important aquatic 

 elements, amounting to sixteen per cent.; neuropterous larvte 

 coming next (eleven per cent.). About two-thirds of the crusta- 

 ceans were crawfishes, the remainder being Cladocera and Copep- 

 oda. The vegetation (nearly one-fourth of the entire food) was 

 chiefly of miscellaneous origin, nine per cent, only being recog- 

 nizable as of aquatic forms. This was almost entirely filamentous 

 Alga3. 



Concerning this fourth group it may consequently be said, 

 roughly, that the food consists of insects, crustaceans, and vegeta- 

 ble debris, about two-thirds of it the first, one-fourth of it the last, 

 and one tenth, the other. 



8 u tn ni a r y f o r the Family. 



If we regard the two hundred and fourteen specimens of 

 fourteen genera which I have studied, as fairly representative of 

 the family Cyprinidje, and strike a separate balance of their food, 

 we shall find that about thirty per cent, of the contents of the 

 alimentary canal consists of mud; that one-half of it, or a little less, 

 is animal matter, and that vegetation amounts to about one-fourth. 

 Insects make one-third of the entire food, about ten per cent, 

 being terrestrial species, eight per cent. Chironomus larvie, and an 

 equal number larvii? of Neuroptera. Of aquatic Coleoptera we 

 have only a trace, and of aquatic Heraiptera (Corixa),but one per 

 cent. Crustacea stand at ten per cent., nearly half of them 

 Cladocera, Entomostraca as a whole amounting to about three- 

 fourths of the crustacean ratio. Fishes are only two per cent., and 

 mollusks less than one. Nearly half the vegetable food consists 

 of Algae (chiefly filamentous forms), the remainder being miscella- 

 neous structures, derived from a- great variety of plants, mostly 

 terrestrial. 



