44 ILLINOIS BIOLOGICAL MONOGRAPHS [44 



early summer of 1925 a photograph of 16 pickerel with a total weight of 

 112 pounds, caught in Muskego Lake, but such catches are unusual, to 

 say the least. Okauchee lake probably has more pickerel than any other 

 lake in the county, and not long ago catches of 15 or more a day were 

 standard. The larger pickerel do some damage by their destruction of 

 game fish. Small bass, sunfish, silverbass, perch, suckers and cisco are 

 preyed upon. I have taken three cisco weighing nearly half a pound each 

 from stomachs of pickerel weighing 8 pounds. The pickerel spawns soon 

 after the ice goes out, passing up into the marsh overflows to deposit their 

 huge quota of eggs. These eggs hatch in about two weeks, the young fish 

 spending the summer in the weed beds along the lake or river shore. By 

 the end of the summer they attain a length of 8 or 9 inches, and have worked 

 out into deeper water near the edge of the bars. A great game fish, that 

 takes any good minnow bait readily and puts up a stubborn fight. Not 

 particularly prized as a food fish because of the many bones. 



56. Esox immaculatus (Garrard). Muskallunge. 



No longer present in the county, there seems little doubt but that this 

 greatest of freshwater game fish formerly occurred in the Fox river, which 

 seems to have been a considerably larger river not very long ago. Dr. P. R. 

 Hoy reports the species from this river, with a specimen weighing 40 

 pounds, caught in 1877. It is certain that the species has been extinct with- 

 in the region for at least thirty years, in spite of reports which reach me 

 constantly. Every large pickerel is suspected of being a "musky." 



Family poeciliidae 



57. Fundulus diaphanus menona (Jordan & Copeland). Menona Top- 

 minnow. 



This is the most abundant of all the Killifishes in the region and is 

 characteristically a lake species. All of the larger lakes, those with gravel 

 and sand shores, such as Keesus, Oconomowoc, La Belle, etc., harbor 

 great numbers of these fish. They are distinctly shallow water forms, 

 seldom entering water more than twenty inches in depth, and are commonly 

 associated with Notropis blennius, Labidesthes sicculus, and young Cen- 

 trarchidae. Of the three species of Killifishes in the region this is the 

 least "top-water" of the group. They remain well toward the bottom, 

 feeding on Crustacea, entomostraca and some insect larvae, and only 

 occasionally come to the top to get a gnat or fly that has fallen on the 

 surface. They spawn very late, often not until late in July, though they 

 seem ready to burst with eggs by late June. An excellent bait minnow 

 seldom more than 2\ inches long. 



58. Fundulus dispar (Agassiz). Top-minnow. 



This interesting killifish has been taken by me only in the Mukwonago 

 Millpond, at the town Mukwonago. Here the species seems to be abun- 



