86 SKETCH OF THE HISTORY OF MAMMALIA. 



In captivity the beaver soon becomes familiar and so- 

 ciable, and, if permitted, will even in a room exercise 

 itself in attempts to build, using brushes, baskets, boots, 

 sticks, and in short anything it can get hold of for the 

 purpose. 



The fine fur of the beaver varies from glossy brovt'n 

 to black ; the tail, or caudal paddle, used as a rudder in 

 diving or in ascending, is flat, scaled, and oarlike. The 

 length of the head and body of a full-grown animal is 

 about forty inches ; of the caudal paddle, one foot. The 

 feet are all five-toed ; those of the hind-feet are united 

 by a broad palmated expansion ; the nails are strong, 

 and that of the second toe of the hind-feet consists of 

 two portions. On land the gait of the beaver is awk- 

 ward and shuffling, owing in part to the outward tour- 

 nure of the hind-feet, which fits them for aquatic pro- 

 gression, and in part to the thick and clumsy configuration 

 of the body. (Fig. 49.) The genus Castor is some- 

 what isolated, and may be regarded as the type of a 

 subfamily. 



The Musquash 



(Ondatra Zibethica ; Fiber Zibethicus, Sabine; Musk-rat, 



^ Godman ; Ondathra of the Hurons; Musquash, "Watsuss, 



or Wachusk, and also Peesquaw-Tupeyew (" the animal 



that sits on the ice in a round form") of the Cree 



Indians). ' 



The dentition of this animal (Fig. 50) presents a close 

 affinity to that of the water-rat and other species of A?- 



3—3 



vicola, as in Fig. 46. Molars, . 



" 3—3 



The musquash is a native of North America, and in 

 its general form it resembles the common watei'-rat, size 

 excepted. In the length of the head and body it mea- 

 sures about fourteen inches, that of the tail being eight 

 or nine. The fur, which is much like that of the beaver, 

 is dark umber brown passing into brownish yellow on 

 the under parts : pied and even white varieties are some- 

 times seen The hind-feet are not webbed ; the tail is 



