133 



it is evident that they had fed upon the hottoni in rather swift 

 water. On the other hand, two specimens had derived nil their 

 food from vegetable sources, and three others had eaten eighty per 

 cent, or more of vegetation. The extraordinary amount of vegeta- 

 tion in the food of this fish is possibly related to the increased 

 length of the alimentary canal. 



SrMMAKY FOR THE GROUP. 



Ninety-five specimens of Group IV examined, representing five 

 genera, had derived about three fourths of their food from the ani- 

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

 insects, one per cent. Arachnida, and eleven per cent. Crustacea., 

 One third of the insects an I spiders belong to terrestrial species. 

 Chironomus larvae are among the most important aquatic elements, 

 amounting to sixteen per cent., neuropterous larvae coming next 

 (eleven per cent.). About two thirds of the crustaceans w-jre craw- 

 fishes, the remainder being Cladocera and Copepoda. The vegetation 

 (nearly one fourth of the entire food) was chiefly of miscellaneous 

 origin, nine per cent, only being recognizable as of aquatic forms. 

 This was almost entirely filamentous Algse. 



Concerning this fourth group it may consequently be said, roughly, 

 that the food consists of insects, crustaceans, and vegetable debris, 

 about two thirds of it the first, one fourth of it the last and one 

 tenth the other. 



SUMMARY FOR THE FAMILY. 



If we regard the two hundred and fourteen specimens of fourteen 

 genera which I have studied as fairly representative of the family 

 CyprinidcTB, 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 ; 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 terres- 

 trial species, eight per cent. Chironomus larvae, and an equal num- 

 ber larvae of Neuroptera. Of aquatic Coleoptera w^e have only a 

 trace, and of aquatic Hemiptera (Corixa) but one per cent. Crus- 

 tacea 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 moUusks less 

 than one. Nearly half the vegetable footl consists of Algae (chiefly 

 filamentous forms), the remainder be^ng miscellaneous structures, 

 derived from a great variety of plants, mostly terrestrial. 



Humming up, in a word, the characteristics of the food of the 

 family as thus indicated, we may say that about one half of it 

 consists of animpl substances, one third being insects, and one third 

 of these of terrestrial species, and ten per cent, being crustaceans ; 

 that one fourth consists of vegetation, about equally aquatic and 

 terrestrial, and that the remainder is mud, probably containing 

 more or less fluid organic matter. 



