62 UNDER THE OPEN SKY 



born; some good students even thought, 

 to the exact locality in the river. So that 

 a shad which had been hatched not far 

 above Trenton came in turn to the same 

 region to lay its eggs and did not follow its 

 fellow-voyagers to the bars farther up the 

 river. But the artificial introduction of 

 shad into the rivers of San Francisco Bay 

 and their gradual spread into those farther 

 up the coast show that this cannot be strictly 

 true, though it is quite probable it is gener- 

 ally the case. As the ice melts at the head 

 of the river and its water grows rapidly 

 warmer than that of the ocean, the shad 

 crowd about the mouth of the stream, often 

 entering the bay and there waiting until the 

 water shall reach a temperature of fifty-five 

 or sixty degrees Fahrenheit. In a back- 

 ward spring the fish may lie in the mouth of 

 Delaware Bay for weeks, sometimes ven- 

 turing up a little but again going back; the 

 regular run may come three weeks late. 



When the great time comes, the horde 

 moves on up the river in a strange zigzag 

 procession. For the fish seem to want to 



