Occasional Papers of the Museum of Zoology g 



A male in breeding attire was caught on the gravelly shoal at 

 Station 30 on June 3, 1919. This fish was about three inches long 

 and flushed with red dorsally, the red being especially brilliant 

 on the head. Every scale on the body except those immediately 

 along the ventral line had several small, granular pearl organs at 

 its exposed margin. 



17. Hybopsis kentuckiensis (Rafinesque), River Chub. — Abun- 

 dant and quite generally distributed in the river, but large indi- 

 viduals appeared scarce, and these were found at but one place, 

 Station 30, where there were breeding activities by males on a 

 gravelly shoal. A deep hole under a log near the upper log bridge 

 was being used by them for a retreat. Three nests in the form of 

 low, roundish, dome-shaped piles of small stones, were in the shal- 

 low water here. The piles were about a foot across and a few inches 

 high, and the stones in them were quite uniform in size, being 

 nearly an inch in thickness on the average and ranging from about 

 a half-inch to two inches in greatest diameter (PI. IV, Fig. 2). 

 These nests were from two to ten feet out from shore and in 

 water ranging from six inches- to a foot in depth. 



On June 3, I watched the building of one of these nests by a 

 large male fish, probably seven inches long, adorned with red 

 ventrally and with prominent pearl organs on the snout. My 

 presence on the log bridge over the stream about eight feet from 

 the nest was disregarded by the working fish a few minutes after 

 I had taken my seat, and he worked incessantly for the hour or 

 more in the early afternoon that he was under observation. Dur- 

 ing the time he built about a third of the nest, and this was evi- 

 dently completed before sundown, for the next morning it had the 

 size and form of other completed nests of the species, and a hard 

 rain following the afternoon of the observations so raised the water 

 and increased the current at the nesting spot that it is not at all 

 likely that the fish could have worked under the changed conditions. 

 The completed pile was about twenty inches in diameter and three 



