Fish-Hatching in a Current of Water. 95 



antlers of the deer, grows with great rapidity 

 at this time. This protuberance is common to 

 nearly all the varieties of salmon and trout, 

 but is developed to a much greater extent in 

 the salmon, and especiallyin the Salmo quinnat, 

 or Californian salmon, found on the west coast 

 of North America. The horny excrescence 

 turns upward, and is sometimes several inches 

 in length ; in some cases a corresponding 

 hollow is formed in the upper jaw, the pro- 

 tuberance being occasionally developed to 

 such an extent as to prevent the fish from 

 feeding, and causing it to die of starvation. 

 In the Salmo salar it is less prominent, and 

 still less so in the trout, and it gets partially 

 absorbed after the spawning season, to re- 

 appear again when the next spawning time 

 returns. 



The ova that have been deposited in the 

 gravel of the river bed, or those that escape 

 the dangers to which they are exposed from 

 their many natural enemies, remain for a 

 period ranging from 50 to 130 days, before 

 hatching. The period of incubation varies, 

 according to the temperature of the water. 

 It has been found that salmon or trout ova 



