NATURAL HISTORY OF AMIA CALVA LINN^US. 75 



fact that in open water each male defends the visible territory immediately about his 

 nest, this frequency can only reach a certain maximum in such water. In sixteen cases 

 the distances between nests located in open water was estimated to vary from two and 

 one-half to eight metres. Sheltered nests so located that the males occupying them 

 cannot see one another may be much nearer together. This is often the case about 

 a log or on the sides of a narrow projecting point of dry land. In one such case 

 seven nests were found within an area estimated to be six by nine metres, and in 

 another case six nests were counted about a log within a circle of four metres radius. 

 In still another case three nests were found within a circle of two metres radius. 

 Dean ('98) gives similar measurements, while Whitman and Eycleshymer ('97) "have 

 never found the nests in such close proximity, never more than four or five in a single 

 bay and usually rods apart." 



4. Guarding of Empty Nests by Males. Evidence that the completed nests 

 are guarded by the male fish previous to spawning has been presented in a 

 preceding section, and the frequency with which this has been observed is there 

 noted. The observations of Fiilleborn ('94) and of Dean ('96) are thus confirmed, 

 rather than those of Whitman and Eycleshymer ('97, p. 319), who "have never observed 

 either the male or female occupying a nest for a number of days or even one day 

 before deposition." The length of time during which the males remain on guard 

 over the empty nests varies greatly. I have noted most frequently periods of from 

 twenty-four to thirty-six hours (twelve cases of twenty-four hours and two of 

 thirty-six hours). In three instances I have noted a period of forty-eight hours. 

 In one case a half-completed nest found on April 19 was not filled with eggs until 

 April 25, a period of six days. Again, a completed nest was found occupied by the 

 male on April 28 at 8 A.M., and he was still on guard over the nest containing eggs in 

 early cleavage stages, evidently laid the night before, on May 1 at 5 A.M., two and 

 one-half days. A half -finished nest guarded by the male was found at 9 A.M. on 

 April 23. In the afternoon of the same day it had been completed. The male 

 was still guarding the empty nest at 9 A.M. April 26, a period of three days. I have 

 a second record of an empty nest guarded for three days. The longest period that 

 I have observed was thirteen days. The nest was found on May 2 at 5.30 A.M.; 

 the male was still guarding it on May 5 at 9 A.M. It was visited at 4 A.M. on May 

 15 and an Amia was found on it. In this case, owing to the sudden departure 

 of the fish, it could not be made out whether it was a male or a female; nor can it 

 be said positively that this was the identical fish found guarding the nest on 

 May 2. 



Nest 71 was found empty and unguarded on April 25 at 9 A.M. On April 26 



