A NEW MUSK RAT. 17 
species of musk-rat, which I have named F%ber 
osoyoosensis. 
The Musk Rat, which I believe is the well- 
known Fiber zibethicus of Cuvier, makes its holes 
in the clayey banks of streams and pools where 
the water runs slowly. The entrance is always 
below the surface, the hole dug up in a slanting 
direction above the water-level. A stage or flat 
place is cleared, which constitutes the dining-, 
drawing-, and bed-room ; leading to the entrance 
of this mansion are a number of open cuttings, 
running in all directions, dug in the mud at the 
bottom of the water. When foraging about, as the 
musk rat usually does about twilight, if alarmed, 
it dives at once into one of these cuttings, and, 
rushing rapidly through, stirs up the mud, thus 
fouling the water, and completely and effectually 
concealing itself. 
The other Musk Rat, which I call Fiber oso- 
yoosensis, differs in size, colour, and structure, 
but particularly in habits, from the preceding. 
This fellow chooses as his haunt a clear pond 
or lake, and in water from three to four feet deep 
constructs a house of bulrushes, in form conical, 
built up from the bottom—how I am at a loss to 
imagine—the roof cleverly arched over into a 
domed shape, and raised about a foot above the 
