II30 



BULLETIN OF THE BUREAU OF FISHERIES. 



approaches the nest and comes a little nearer, but again flees as the male turns 

 toward her. As female after female thus approaches the nest their coyness 

 gradually diminishes, until one, bolder than the rest, enters and does not flee 

 as the male approaches. She gives no assistance in building, for that is the 

 work of the male. As she enters the nest the male first turns toward her and 

 then, as she comes nearer, takes up his position at the botton; of the pit at the 

 lower end of the gravel ridge, as shown in figure 3, page 1 126. He lies usually 

 nearer the bottom of the pit than shown in the figure and often turned some- 

 what on one side, and in this position he waits until the female has taken a 



position just above him or at 

 his side. Even when the female 

 has come so far she often again 

 flees, and in that case is pur- 

 sued by the male, who attempts 

 to bite or hook her. Usually 

 when she has come near enough 

 the male gets his head and his 

 expanded pectoral fin of one side 

 beneath her, and then with a 

 movement often too rapid to be 

 followed by the eye he tosses 

 her into an upright position and 

 at the same time encircles her 

 body with his own. When this 

 has happened the two fish are 

 in the position shown in figure 

 15, plate cxx, and text figure 5, 

 page II 30. Then the male im- 

 mediately straightens his body 

 and releases the female. The 

 length of time required for the 

 male to clasp and release the 

 female varies, but is always very brief. It appears to take about as long 

 as is required to close and open the hand when that movement is performed 

 as rapidly as possible. This seems to be usually one-tenth of a second, but 

 is- often more. 



When the two fish are in the position shown in text figure 5, the surface 

 of the opercle of the male is seen to be pressed against one side of the female, 

 while the side of his body back of the dorsal fin is pressed against her other 

 side. At the same time the upper surface of his pectoral fin of one side is 



Fig. 5. — Male and female horucd dace during the spawning act. On 

 the male, which is the fish with the body cur\-ed. are shown above 

 the eye and in line with the nostril, four spine-like pearl organs and 

 below these two smaller spines. Small organs are seen on the oper- 

 culum and dorsal surface of the pectoral fin and on the caudal edges 

 of the scales on the tail. 



