78 ANIMAL COMPETITORS 
muskrats, but should only be employed in ex- 
ceptional circumstances. The most valuable 
works open to their attacks should be con- 
structed of or faced with rubble or concrete to 
a proper depth. 
Muskrats worth far more than the damage 
they do. As amatter of fact the harm done by 
muskrats is, on the whole, far outbalanced by 
their value in fur, so that in Canada, and in 
many states of the Union, the animal is pro- 
tected during a close season (April to Novem- 
ber), when its young are being nurtured and 
the fur is not ‘‘prime,’’ i. e., in good condition 
for market. These states are Delaware, Illi- 
nois, Iowa, Maine, Maryland (coast counties), 
Michigan, Minnesota, New Jersey, New York, 
North Carolina (coast counties), South Dakota, 
Virginia (coast counties) and Wisconsin. This 
protection, however, ends too early in the fall. 
The open season should not begin in the United 
States before December 15, and should close by 
March 15; in Canada it may be slightly pro- 
longed. 
The muskrat supplies one of the most useful 
and dependable sources of fur for clothing, and 
