NATURAL HISTORY OF AMIA CALVA LINNAEUS. 71 



to know this ratio for those Amias taken in commercial nets at other seasons than 

 the breeding season. The number of fish taken in 1898 would seem to show the 

 males about eight times as numerous as the females. In this case, however, the net 

 was in use during only the first part of the breeding season. The fact that during 

 this first week of the breeding season of 1898 eight times as many males as females 

 sought the spawning ground was at first interpreted to mean that the males go first 

 to the spawning ground, but the numbers obtained in 1900 do not admit of this 

 interpretation. 



A comparison of the numbers obtained for the two seasons, as indicated in the 

 tables, shows that some of the males may go to the spawning ground in advance 

 of the females (1898) or that the sexes may go together, and that when they do go 

 together the ratio of males to females varies during the season (1900). While the 

 males are engaged in nest-building in the bay described above, the females are 

 probably usually present in considerable numbers in the vegetation of the deeper 

 water at the centre of the bay, where no nests are built. 



Secondly, the experiment of 1900 seems to me to show that male fish kept in a 

 sufficiently large enclosure of the natural spawning ground make nests either when 

 no females are present or when very few are present in comparison with the number 

 of males. In this experiment the eggs found in the five nests could not have been 

 laid by more than five females, and were probably laid by one or two, while the 

 number of nests constructed before these eggs were laid was twenty-four. That no 

 more nests were made by the large number of males within the enclosure is due to 

 the fact that there was not space for more, since each male when he has begun his 

 nest drives other males away for five metres or so in all directions in which he has 

 unobstructed view. We cannot suppose that the one to five females present in this 

 enclosure assisted in making the twenty-four nests, and we are thus forced to the 

 conclusion that the males alone made these nests. 



Since the males are at times seen working at the nests; since the completed nests, 

 while still empty, are guarded by male fish; and since when males are confined in 

 enclosures in which are few or no females, nests are there built in such large numbers 

 that the females could not have assisted in their construction, we may conclude 

 that the males, and the males alone, are the nest-builders. In this respect Amia does 

 not differ from those nest-building teleosts to which reference will be made in another 

 place. 



E. Method of Nest-building. — The method of building the nests is difficult of 

 direct observation. In a nest that has been very recently worked at by the fish the 

 water is still roily when the observer reaches the nest. This condition I have noted 



