NATURE'S CALENDAR 65 



brook and pond life, but in tlie larger April 11 



streams a still more interestin^j; series of 



facts is taking place during these mid- 

 spring days, in the coming of the migra- 

 tory fishes from the sea. The most prom- 

 inent example all along our northern coast 

 used to be the lordly salmon — and even 

 yet April sees a few of them entering the 

 clear rivers of Maine, climbing the rapids 

 and leaping the cataracts as of yore in 

 eager haste to reach their autumnal breed- 

 ing-places at the forest- hidden sources of 

 the stream. Some are now seen annually 

 in the Hudson. 



Other anadromous fishes — as these are 

 called which annually resort from the 

 sea to fresh waters — remain to us, and it 

 is still a matter of livelihood and enjoy- 

 ment to many people that every spring 

 the herrings, alewives, the shad, and many 

 others crowd into our watercourses from 

 the ocean. 



Much mystery still belongs to this 

 regular migratory movement of these 

 fishes. We can trace them in the rivers, 

 know when they arrive and when they 

 depart; but where the winter is spent, 

 and how they are moved to return each 

 spring to the fresh water, are little under- 

 stood. Nearly all these fishes appear 

 first in the extreme south, entering Flor- 

 ida rivers long before the northern ones 

 are free from ice, and gradually occu- 

 pying the latter as they become open and 

 sufficiently warm. Temperature seems 



