The Food of the Smaller Fro^h- Water Fhhes. 71 



troduction to tlio Study of Fishes." Altl;ouo-li our <ronora both 

 belong to the carnivorous section, it will be seen that they are not 

 by any means strictly eoniined to animal food, vegetation mak- 

 ing about one-tifth ol' their usual nutriment. 



FuxDULUS Di.\.piiAxus, LeS. Barred Kir.i.iFisn. 



This species is very abundant in the northern part of the State, 

 especially in lakes or in clear and sandy streams, but we have not 

 taken it anywhere in Central or Southern Illinois. Most of our 

 collections were made in the lakes of Lake and McHenry Coun- 

 ties. 



The intestine is shorter than the body, the gill-rakers are short, 

 obtuse, and few in nund)er, the pharyngeal jaws are of the pave- 

 ment type, set with fine, sharp teeth, and the mouth is small, but 

 extraordinarily protractile. 



Eight specimens were studied, from Crystal and Cedar Lakes. 

 About four-fifths of the food consistetl of animal substances, the 

 remaining fifth of vegetation. Except a few filamentous Alg:\i 

 taken by one of the specimens, the latter consisted wholly 

 of seeds of various plants fallen into the water. Eighty per cent, 

 of the food of two of the specimens, and twenty per cent, of that 

 of a third consisted of such seeds; ratios evidently too large to have 

 been taken accidentally. Two of the specimens had eaten Plan- 

 orbis, and all had eaten insects, which made about forty per cent, 

 of the food; terrestrial species, including spiders, making twelve 

 per cent. Among the aquatic forms were Chirononuis larv;e, Hy- 

 drophilidiij, and larvjti of Ephemerid;e, the latter eleven per cent. 

 Crustacea were a fifth of the food, chiefly the abundant amphipod, 

 AUorchestes dentata. Cypris and Candona were likewise noticed 

 in considerable quantity (seven per cent.), and a few specimens of 

 various Cladocera occurred. 



Zygonectes xotatus, Raf. Toi> Minxow. 



This species ranges in ponds and sluggish streams throughout 

 the State, but is most abundant southwards. Here it may com- 

 monly be seen swimming slowly about in stagnant pools, with the 

 head at the surface of the water, as if interested in the phenomena 

 of the weather, or possibly watching for the appearaiice of terres- 

 trial insects. The alimentary structures are in all respects similar 



