BREEDING HABITS OF RAINBOW DARTER. 53 



which the brilliant males are successful, the fact that they are 

 the largest and most vigorous and the advantage which results 

 to them from their position during the spawning act, makes it 

 probable that much the larger part of the eggs are fertilized by 

 them. 



VI. Discussion of Results. 



i. Origin of Nest-Building Habits. 



The facts here presented show clearly that certain large males 

 have holdings which they guard and over which they remain, 

 while the females and young males are moving about in the 

 breeding area. The way in which these areas come to be held 

 by the large males was not observed, but it seems possible that 

 the result has been reached in the following manner : As the 

 female moved about at the beginning of the season with the 

 males following her, she attempted to bury herself, but owing to 

 the hardness of the bottom was at times unsuccessful. She re- 

 peated her attempt until she came to a place where the bottom 

 was loose, and where she easily worked herself into the gravel 

 (cf. for Salmon, Rutter, 1903). Then spawning took place. 

 When she moved she again succeeded in burying herself where 

 the sand was loose. Since the large males were able to drive 

 away the smaller ones, they appropriated to themselves those 

 areas within which the bottom was of a character suitable for 

 spawning. These were their holdings. When a male had once 

 taken possession of a holding he received into it a succession of 

 females and guarded it continuously against the intrusion of 

 other males. In this way he not only secured to himself the 

 successive females that visited his holding, but incidentally he 

 guarded the eggs that had been deposited in it and prevented 

 their being eaten by the females and by other males. By this 

 method the breeding area may have come to have a number of 

 holdings, each defended by its male. 



In Etheostoma the male does not in any way prepare the hold- 

 ing for the reception of the eggs, but these are laid here and there 

 at random wherever the bottom proves suitable. There is in this 

 case no real nest. It has been noted that among certain fish 

 which do in one way or another prepare a nest for the eggs, an 



