THE STRUCTURE AND ACTIVITIES OF FISHES 277 



occurs from July to December, according to the temperature of 

 the water, which apparently must be below 54 Fahrenheit. 

 The eggs are deposited upon the gravelly bottoms of the streams, 

 after which both males and females die; consequently an indi- 

 vidual spawns only once in its lifetime. The eggs hatch in about 

 seven weeks, and the young remain on the spawning ground for 

 six weeks. They then float slowly downstream and may be four 

 or five inches long when they reach the sea. 



REFERENCES 



Fishes, by D. S. Jordan. Henry Holt and Co., N. Y. City. 



The Fishes of North and Middle America, by Jordan and Evermann. 



Bulletin No. 47, U. S. National Museum, 4 volumes. 

 Bulletins published by the U. S. Fish Commission. 



