520 



REPOKT OF THE COMMISSIONER OF FISHERIES. 



Twenty-two of these fish contained l)ut one kind of food, and then 

 generally but one or two specimens of the latter was large. One bass 

 had eaten 4 minnows and another 2 frogs. 



Forbes (c, d) found that this species of black bass contained about 

 the same variety of food as recorded b}' us; he found that fish con- 

 stituted the largest percentage of food, and in much smaller quantities 

 crawfish, insect larva?, and algse. 



None of the bass we examined was free from parasites, the nearest 

 approach being one fish from Avhich we took but a few C3\sts in the mesen- 

 tery. Cestodes were more prevalent than any other parasites, although 

 Acanthocephala were nearly as numerous. The following table gives 

 the places in which parasites were found, and the number of fish in 

 which each kind vs^as present: 



Copepods [Ergasilits) on gill, 4; cestodes in ovary, 4; cysts in mesentery, 1; cestodes in body cavity, 

 1; cysts in liver, 2. 



The trematodes were Azygia tereticolle^ A. Joossii^ Cxcincola par- 

 vulus^ and Leuceruthrus microliter i. One of the cestodes w^as a species 

 of Proteocephalus. 



12. Perca Jlavescens^ j^ellow perch. 



The perch, caught mostly with hook and line, were taken from 

 Lakes Mendota, Monona, and Wingra — all but a few from the first- 

 mentioned lake. The Lake Mendota perch were nearly all caught near 

 the shore, a few only coming from deep water. An exception to this, 

 however, was a lot of perch, IG in number, purchased in February 

 from fishermen, who caught them through the ice at quite a distance 

 from shore and in deep water. The food and parasites of these were 

 quite difi'erent from what we found in the others, and, although at 

 present included with the others, separate mention of tliem will be made 

 later. Excepting these, all were caught in April, May, or July — more 

 during May than at any other tiiue. 



Seventy-two perch were examined, in only 9 of which were para- 

 sites absent. A few of the others had no parasites in the alimentary 

 tract, but contained cysts in the mesentery or liver. Fifty -six of the 

 perch contained food the nature of which we could determine, and of 

 the remaining 16 a few had food remains in the lower part of the 

 intestine or in the rectum nothing as to the nature of which was 

 recognizable. The following table gives the different kinds of food 

 and the number of fish in which each kind was found: 



