THE SPAWNING HABITS OF CHROSOMUS ERY- 

 THROGASTER RAFINESQUE.* 



BERTRAM G. SMITH. 



While a student at the University of Michigan during the 

 years 1904- 1907 I acted as assistant in zoology and when 

 accompanying Professor Jacob Reighard on field excursions had 

 many opportunities to observe, under his guidance, the breeding 

 habits of minnows and other fishes. This familiarity with the 

 unpublished work of Professor Reighard made it possible for me 

 to make the observations recorded below, which are published 

 with his permission. 



About the middle of May, 1907, I found the minnow CJiroso- 

 imis erythrogaster Rafinesque very abundant in a small brook 

 near Lake Forest, 111. As the males were in breeding dress I 

 seized the opportunity to make some observations on the 

 spawning habits. 



Habitat. — The brook flows through a large open pasture and 

 also through woodland ; the minnows were far more numerous 

 in that portion of the brook which is in the open field. Here 

 the stream meanders through a shallow valley, over a pebbly or 

 sandy bottom. In places it is so narrow that one can readily 

 step across it ; elsewhere it expands into pools or shallow rapids 

 not more than six feet wide. In the rapids the water is seldom 

 more than two or three inches deep ; in the pools it may reach 

 a depth of one or two feet. The current is quite rapid ; even in 

 the pools there is little quiet water. 



Chrosomus is by far the most abundant fish in this brook. 

 Schools of from a dozen to several hundreds abound, while of 

 other fishes only a few large suckers, and an occasional Rhijiich- 

 thys, Seniotilus and Cottns, were observed. 



Sexual DiniorpJiism. — The bright colors of the males were 

 scarcely noticeable when the fishes were in the water and viewed 

 obliquely from above ; but when removed from the water the 



* Contributions from the Zoological Laboratory of Syracuse University. 



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