56 ILLINOIS BIOLOGICAL MONOGRAPHS [56 



stead in its habitat. The food is largely insect larvae, Simulium predomi- 

 nating when the form is in season. These, together with mayfly and small 

 dragon fly nymphs, Planaria, and occasionally young leeches make up the 

 bulk of the food, while entomostraca and tiny gastropods are also items. 

 During the breeding season the cheeks of the male swell up, each spine of 

 the first dorsal fin develops a tiny white mushroom-shaped tip, the color 

 deepens, and the fish becomes really an exquisite example of the darter 

 group. They spawn just below the rapids, usually behind a stone, clearing 

 out a shallow depression in the immediate vicinity of which the now very 

 pugnacious male patrols. Infection with cysts of (?) Diplostomulum cuticola 

 is not infrequent, but never heavy. They spawn in June. 



86. Boleichthys fusiformis (Girard). Spindle-shaped Darter. 



This is one of the rarer species of darters in the county, and has been 

 taken by me in Oconomowoc, Pine, and La Belle lakes, and in the Bark 

 river. It is a fish of quiet water and hard bottom, avoiding dirty conditions 

 entirely. A depth of about 18 inches of water is preferred, and the fish 

 show little of the typical darter characters of behavior, rather resembling 

 Etheostoma iowae in this respect. I have, however, taken them in tribu- 

 taries of the Bark river in much shallower water, amid heavy vegetation. 

 Gravid females have been taken in May and only once as late as May 30. 



87. Microperca punctulata (Putnam). Least Darter. 



This tiny darter, by far the smallest of the group, is quite rare in 

 Waukesha county, having been taken by me only in the Bark river north 

 of Rome, on the very western edge of the county. Here, however, it is 

 locally common, inhabiting water of 2 feet or more in depth, heavily 

 loaded with Potamogeton and Elodea. It avoids any considerable current, 

 preferring the quiet, deep pockets along the muddy shores, associated with 

 young Pomoxis sparoides and Micropterus salmoides, which in turn feed to 

 some extent on it. Giants of the species measure If inches, but the average 

 size is under one inch. Their food is entirely animal matter, being about 

 equally divided between insect larvae, nymphs and entomostraca. It is 

 an exquisite little fish whose reticulate markings remind one of the fan- 

 tailed darter {Etheostoma fiabellare lineolatum) while the lateral markings 

 resemble those of the Johnny darter (B. nigrum). 



Family serranedae 



88. Roccus chrysops (Raf.). White Bass; Striped Bass. 



Another introduced species which has taken firm hold in a large number 

 of lakes. In La Belle and Pewaukee the fish are very abundant, while the 

 species is present in somewhat lesser numbers in Oconomowoc and Naga- 

 wicka. The most gregarious of our fresh water fishes, the adult white bass 

 seem at all times to travel in large schools of several hundred individuals 

 while the young are apparently solitary. During most of the year the fish 



