216 IOWA ACADEMY OF SCIENCE Vol. XXV. 1918 



28 Trichopterous larvae. 

 23 eggs, probably fish eggs, 

 lit. H 7-16 incaes long. 



2 Cambarus propinqus. 

 6 Gammarus fasciatus. 



1 Campeloma (Gastropoda). 



52 fish eggs. 



1 Trichopterous larva. 



20. 5 5-16 inches long. 



6 Crustacean? eggs. 



297 Hyalella knickerhockcri 



3 Gammarus fasciatus. 

 1 Trichopterous larva. 



1 Basiaeschna nymph } 



4 Ischnura ve>'ticallis nymphs \ ^'^^^^^^ 

 6 water mites (Hydrachnlda). 



3 fish eggs. 



2 Chironomiis larvae. 



4 Chironovins pupse. 



21. 41,4 Inches long. 



142 Chironomus larvae. 



1 Chironomus pupa. 



2 Hydrachnids. 



1 Enallegmu nymph (Odonata). 

 1 Ischnura verticallis numph. 

 Remains of several Tricnopterous larvae, their number im- 

 possible to ascertain. 

 30 Hyalella knickeVbockeri. 



Of the fish examined two ages predominated, one and two 

 year olds. The larger fish seemed to feed on smaller organisms 

 such as Chironomid^e, Triohoptera and Gaminaridce as mueh as 

 on prey of greater size. 



The presence of twelve sticklebacks, {Eucalui. i)iconstans) , in 

 the stomach of one perch was somewhat of a surprise as previous 

 investigators have not mentioned this fish as lood of the perch. 

 Since Forbes (1878-80), and Baker (1916), reported Corixida? as 

 oecun'ing rather commonly in the stomach of the perch it seems 

 strange that none was found in this lot, while the fact that 

 only parts of two mayflies (Ephemeridai), were found was also 

 quite nnlooked for, inasmuch as perch have been ol)served feed- 

 ing almost entirely upon mayflies during the June transforma- 

 tions of these insects. Crustacea were present in thirteen stom- 

 achs with evidence of their having been in another. Of tliese 

 Decapods represented by Camharus were in eight while Amphi- 

 ])ods were found in ten, these being mostl.v Gammarus and 



