45J STUDY OF SOUTHERN WISCONSIN FISHES— C AH N 45 



dant. The water of the millpond is dark due to much sediment in suspen- 

 sion, and has very soft mucky banks and reedy shores. Among these 

 reeds this species is seen swimming just under the surface, or even some- 

 times with the dorsal fin out of water, feeding largely on tiny insects that 

 chance to fall in the water. They are rather slow in their ordinary move- 

 ments, but zig-zag away rapidly if disturbed, usually to return very 

 shortly to the spot they left. 



59. Fundulus notatus (Raf.). Top-minnow. 



Next to F. diaphanus menona, the commonest of the killifishes. They 

 frequent rivers and streams in preference to lakes, and I have taken them 

 in Battle creek, and in all of the river systems except the Menomonee. 

 They prefer slowly flowing water, and do not seem worried by sediment 

 in suspension. Like the preceding species, this top-minnow remains 

 constantly just under the surface, and when disturbed it zig-zags wildly, 

 but it does not descend. Yet their food habits are in striking contrast to 

 the preceding: about 75% of the food is vegetable matter, almost wholly 

 filamentous algae, Spyrogyra, and Zygnema predominating. The remainder 

 of the food is mostly insects picked from the surface. They spawn late, 

 seemingly carrying nearly mature eggs for several weeks. I have taken 

 gravid females from June 10 to July 8. One of the stable foods of the 

 small-mouth bass (Micropterus dolomieu) that inhabit the rivers. 

 Order ACANTHOPTERI 

 Family gasterosteidae 



60. Eucalia inconstans (Kirtland). Brook Stickleback. 



The characteristic inhabitant of small, weed-choked creeks, so heavily 

 overgrown with brush, usually willows, as to be almost invisible. In such 

 little streams, tributaries to the Scuppernong river and creek of the same 

 name particularly, this pugnacious little fish builds its nest, rears its young, 

 and lives its life. This is the only fish here that actually builds a nest, 

 in the usual sense of the word. This nest, made of tiny twigs and branches 

 of water plants, is almost round in shape, and is well hidden in the dense 

 aquatic vegetation. The fish guards the nest vigorously, and will strike 

 at anything that intrudes on the premises, including the finger if it is 

 advanced slowly. The food is largely insect life, over 50% being small 

 non-aquatic insects that fall into the water. An interesting variation in 

 the number of dorsal spines exists among the sticklebacks of Scuppernong 

 creek particularly. While 5 is the typical number, both 4 and 6 occur. 

 Out of 100 fish examined, 13 had 4 spines, 69 had 5 spines, and 18 had 6 

 spines. 



Family atherinidae 



61. Labidesthes sicculus (Cope). Brook Silversides; Top- water. 



In southern Wisconsin this is characteristically a clear-water lake 

 species, seldom found in streams. Especially abundant in Oconomowoc 



