Figure 1.— Hind foot of the muskrat. 

 Left, dorsal view ; right, ventral view. 



covered with small, scaly areas and 

 strongly compressed laterally, is 

 an efficient rudder for swimming. 

 Long, sharp claws serve admirably 

 for digging and defense (fig. 1). 

 The large hind feet, which can be 

 turned sidewise to reduce resistance 

 when the muskrat is swimming, are 

 not webbed but have fringes of 

 short, stiff hairs that also help in 

 swimming. The dense pelage is 

 practically waterproof — the long, 

 stiff, glistening brown guard hairs 

 closely interspersed among the 

 short, soft, and exceedingly dense, 

 gray underfur. 



The muskrat has four protrud- 

 ing, chisellike incisors to cut its 

 food, and heavy molars to grind it 

 ( fig. 2 ) . The incisors grow contin- 

 uously and are gradually replaced 

 when broken. By closing its lips 

 tightly around the protruding in- 

 cisors and blocking the small open- 

 ing between them with its tongue 

 (fig. 3), the muskrat can gnaw and 

 dig loose root material under water. 

 Short, bristlelike hairs cover the 

 lips and protect them from sharp 

 grasses or other rough food plants. 



A deep cleft between the upper and 

 lower lips lets the muskrat open its 

 mouth wide and carry large mouth- 

 fuls of food or nest-building mate- 

 rials. 



A pair of highly developed scent, 

 or musk, glands are located under 

 the skin in the lower inguinal re- 

 gion (fig. 4). These yellowish 

 glands, much larger in the male 

 than in the female, appear rough- 

 ened or corrugated. They give off 

 a pungent, musky odor that is par- 

 ticularly strong during the breeding 

 season and accounts for the name 

 "muskrat." The old Cree name 

 "musquash" is still used in Canada 

 and in continental European fur 

 markets. 



Distribution and Habitat 



Two distinct species are recog- 

 nized: the Newfoundland muskrat 

 {Ondatra obscurus) and the com- 



FiGURE 2.— Lower and upper parts of 

 muskrat skulls, showing incisors and 

 grooved molars. 



