1046 Observations on the Muskrat. [ November, 
by the railroad company. Where they have constructed gravel 
banks and kept them free from vegetable growth, it is rarely they 
are bothered. Trenching the banks and filling in the trenches 
with gravel has proved of considerable value, while some protec- 
tion has been afforded by a top-dressing of coarse gravel over an 
old bank of loam, provided vegetation is not allowed to grow 
thereon. When these precautions have not been taken, great 
damage is done each year; the burrows of these animals are con- 
tinually being enlarged, and caving in, cause a leak, or undermine 
the railroad track, as the case may be. 
In early spring the greatest damage is done. With the alter- 
nate freezing and thawing at that time of the year, the coverings 
of these underground passages drop in, exposing cavities of sur- 
prising extent to one who does not know the amount of subter- 
ranean work this animal is capable of doing. It requires vigilant 
work of eyes and ears to prevent this caving causing great dam- 
age to property. The underground homes of the muskrat in the 
banks of the canal have each two openings. When the water is 
at its usual stage an opening may be found, the upper edge of 
which is on a level with the surface of the water; another hole. 
may be seen at low-water mark, the top of which is just level 
with the surface of the water at that stage. These holes are 
generally from eighteen inches to two feet apart. The pas- 
sages from these openings lead backward and upward in a very 
crooked way, as any one who has attempted to follow them 
up can testify. These passages end in a large gallery which is 
the home of the animal. From this chamber a small passage 
leads to the surface, ending amid a bunch of grass or weeds. By 
this means the gallery is ventilated. The holes at the surface are 
known as “air holes.” They are not always found, at least I 
have not in all instances observed them. In heavy ground an 
“air hole” is always found, while in porous ground it is as often 
absent as not, These underground burrows extend into the bank 
a distance of ten to twenty feet in a straight line, as a rule. In- 
stances have been noted where the depth reached was less than 
_ the minimum given above, but such are rare. In localities along 
= small streams which are subject to sudden rises, the distance 
attained occasionally reaches thirty feet, but in all instances the 
depth to which these burrows reach depends, in a great measure, 
s emg size and SALEN of a bank as well as upon the 
of hboring stream to sudden changes of level. 
