TROUT BREEDING. 33 



for them, as they burrow under water only where the bank 

 is high enough above it to allow them room for their nests. 

 In severe weather, when the ground is covered with snow, 

 muskrats are driven by hunger to feed on grass, which may 

 even then be found on the margin of spring water, or they 

 may come into it for the warmth it affords. When they 

 nib the grass, much of it is set adrift and clogs the wire 

 screens, at least I have found it so in my experience. On 

 this account it would be well to have the margin of the 

 raceways and ponds gravelled. A great inconvenience is 

 experienced in keeping the screens at the outlets from be- 

 coming clogged with leaves and floating trash. There should 

 therefore be a coarser screen to act as a leaf catcher, placed 

 before each of those intended to keep the fish in their 

 respective ponds. Seth Green, at Caledonia creek, that he 

 may prevent the fish in his ponds from running up into the 

 mill-pond that supplies them, has a water-wheel turned by 

 the current at the head of the raceway, the edges of the 

 buckets or paddles coming so close to the concavity of the 

 frame in which it revolves, as to keep the fish from ascend- 

 ing, while those from above can descend between the 

 buckets. Floating grass and leaves also pass without 

 obstruction. This contrivance, however, although it will 

 keep the large fish in the last pond, will not prevent those 

 of pond No. 1 from running down into No. 2, and the fish 

 of both from getting into pond No. 3, where the yearlings 

 would be devoured. 



POND No. 1 being for the small fry, from the time they 

 leave the hatching-troughs or nursery, until they are some- 







