52 ILLINOIS BIOLOGICAL MONOGRAPHS [52 



and go into deep water where many must fall prey to larger fish. However, 

 young pike are extremely pugnacious and begin their piscivorous diet 

 when 5 or 6 days old. In my collection I have a string of seven wall-eyes of 

 this age, each member of the string with the posterior half of the preceding 

 pike well down his throat. Thus the whole string died. The fish attain a 

 good size; I have records of many weighing between 7 and 10 pounds, and 

 I have no doubt that 15 pounders are not unknown to Golden, Oconomowoc 

 and the Nashotahs. They are frequently the host to the peculiar ecto- 

 parasite Argulus stizostethi which crawl over them much in the manner 

 of lice. 



75. Stizostedion canadense griseum (DeKay). Gray- Pike; Sand Pike; 

 Wall-eye. 



This species, like the preceding, has been widely introduced throughout 

 the county, and is never distinguished by local fishermen who take it 

 for small fish of the preceding species. They differ from the preceding 

 markedly both in coloration and in size. This fish is distinctly of a gray 

 tinge while the other is very golden. Furthermore, this species is much 

 smaller, seldom exceeding a pound or a pound and a half. They are very 

 abundant in Forest and La Belle lakes, much less so in all the other lakes. 

 Their general habits and food are so nearly like those of the preceding 

 species that they need not be discussed. Decidedly a less desirable table 

 fish because of its smaller size. 



76. Perca fldvescens (Mitchill). Perch. 



Abundant in all of the lakes and rivers in the county. The large perch 

 are distinctly a deep water fish, inhabiting the Potamogeton beds in the 

 deep water off the edge of the bars. If one were to make a survey of the 

 water between here and the shore, one would find a gradual decrease in 

 size of the perch correlated with a decrease in the depth of the water, 

 with the young-of-the-year in the very shallow water along the shore 

 associated with Notropis blennius and N. hudsonius. The nest is a shallow 

 depression in the sand along the shore and here a string of very beautiful 

 eggs is laid. The young remain in the shallows and attain a length of 

 about three inches by fall. The food of the young is largely entomostraca 

 and insect larvae while that of the big adults is largely crayfish and min- 

 nows. Like the green bass (M. salmoides) and silverbass (P. sparoides) 

 the perch is active and feeding all winter and thousands of them are 

 caught through the ice when they are so heavy with spawn that they can 

 barely flop. Such fish often weigh a pound or a pound and a half. A very 

 excellent table fish, readily caught on either worm or small minnows. 



Subfamily etheostominae 



77. Percina caprodes (Raf.). Log-perch. 



A common species of darter in the deeper portions of the larger rivers, 



