40 



CORA D. REEVES. 



head of the rapids where the stream leaves a pool. Here the 

 water is from one and one half to four or six inches deep with a 

 current moving at the estimated velocity of about 75 feet per 

 minute. The pebbles of the bottom are small, averaging one 

 half inch in diameter while the largest is not over two inches. 

 As these gravel sheets are the areas used by the dace (Semotilus 

 atromaculahis) and stone-rollers (Campostoma anomalum) in nest- 

 ing, the ground is often roughened by their pits and ridges. 



MHHW 



Fig. 2. The breeding ground of Etheostoma c&ruleum Storer. The stream is 

 here about six feet wide. The stone at /. is about a foot long. The numbers indicate 

 the holding of fish "A." 



The change in the behavior of the darters is as marked during 

 the breeding season as the change in color or habitat. While 

 the fish are at other times shy, rushing for shelter on one's ap- 



