136 ILLINOIS ACADEMY OP SCIENCE 



Now and tlien two fish, evidently males, would crowd 

 on either side of a sombre fish, very probably a female, 

 and there would follow much bodily agitation and 

 water disturbance. This was undoubtedly the spawn- 

 ing act and is like that described by Culbertson ('04, p. 

 65) and by Keighard ('20, p. 10). A collection of these 

 breeding fish was made by me, and I was interested to note 

 that on capture they lost their intense black markings in- 

 stantly. Small pearl organs were found on the males 

 taken and on two of the females in this collection; both 

 were spawning fish with eggs streaming from their bodies. 



Keighard (1. c. '04, p. 212) notes the use of pearl organs 

 in suckers for maintaining contact of the sexes during 

 spawning and ('20, pp. 3-15) treats in detail the breeding 

 behavior of the species as observed in southern Michigan. 

 Fowler ('12, p. 474) notes the distribution of these tuber- 

 cles in breeding fish examined by him, but he found none in 

 the females. Neither did Keighard ('20, p. 7). 



Hypenteliiim nigricans (LeSueur), Hogsucker. 



This species appeared to be breeding in Riley Creek 

 about two miles west of Charleston on April 11, 1910. In 

 a broad expanse of shallow water where the stream was 

 about twenty feet wide and but a few inches deep, two of 

 these fish were seen, one chasing the other and finally set- 

 tling with the sides of their bodies together. They re- 

 mained quietly in this way for some minutes. At another 

 time in this same stream in a similar place two Hogsuckers 

 were seen to take this position, but this time there were 

 active movements of the body as in the case of the spawn- 

 ing Common Suckers. 



Little has been found in literature on the breeding of 

 this species. Keighard ('04, p. 212) describes the spawn- 

 ing act of this fish, calling it the Black Sucker ('20, p. 20) 

 and gives an account of the sexual difference in the species 

 and the breeding activities as noted near Ann Arbor, 

 Michigan. Meek and Hildebrand ('10, p. 257) say that it 

 ascends streams in the spring to spawn. Wright and Allen 

 ('13, table) note the Hogsucker as breeding in shallows of 

 swifter brooks in April and May. 



