30 



Stone rollers, blunt-nosed minnows, and black head rriiinnows 

 feed largely on soil rich in diatoms. Chironomus larvae and 

 entomostracans formed the bulk of the food found in silver 

 mouthed minnows and the blue-spotted sunfish. Some chub 

 suckers had fed entirely upon soil and diatoms, and others upon 

 entomostracans and Chironomus larvae. The horned dace ex- 

 amined had a miscellaneous lot of insect fragments in their 

 intestines including Chironomus larvae and terrestrial insects. 

 By further studies of the food of the fish of Campus creek, 

 it is hoped that the distribution of the organisms used as food 

 can be correlated with that of the species of fish that feed 

 upon them. 



Temperature. This eflfects the distribution of the fish in the 

 stream indirectly and probably directly, but I have failed as yet 

 to find any marked relation between temperature of water and 

 fish distribution. They have been seen both active and inactive 

 in winter when the water was near the freezing point. The 

 largest number of fish ever seen by me in Campus creek was 

 on January 28, 1506, when the water temperature was 6 de- 

 grees centigrade. 



Some stone rollers taken at this time had their intestines 

 filled with soil and diatoms. One winter I gave particular 

 attention to a lot of fish that were remaining over winter in a 

 pool in one of the tributaries of Campus creek, and I could see 

 no relation between their behavior and the water temperature. 



Shore vegetation. As above stated, a grassy bank borders 

 the stream almost everywhere, and this in many places over- 

 hangs the water due to the mat of soil and roots at its top edge, 

 which resists erosion more than the portion belowi it. Under. 

 this shelf, fish and other aquatic animals like snails and various 

 insects find a place of seclusion. From observations made on 

 Campus creek it appears that fish are more often found where 

 overhanging banks are present than at other places. Roots 

 of trees also hold on to the soil, and often produce large over- 

 hanging banks ; and where the roots are submerged, a habitat 

 of a peculiar type is produced, for among them there is an in- 

 tricate series of cavities in which fish often stay. The leaves 



