71 RAMBLES ABOUT HOME. 



animal, but also in relation to the great majority of our 

 mammals. 



Besides the extensive burrows in which, during tlie 

 greater part of the year, the musk-rats live, they often 

 erect, in autumn, quite elaborate structures, in swampy 

 ground, or occasionally in shallow and quiet waters, when 

 they can find safe anchorage, as for instance to a stump. 

 These winter-houses, as they are usually called, are coni- 

 cal in shape, and generally about three feet in diameter, 

 at the base, and two or three feet in height. The mate- 

 rials used in their construction are long, coarse grass, bul- 

 rushes, twigs, and some of the larger limbs of shrubs. I 

 have never discovered any evidence that, beaver-like, 

 they gnaw off saplings of water-birch for the purpose of 

 using them in house-building, but that they do so, at 

 times, has been asserted by many. The materials gath- 

 ered are closely cemented with stiff, clayey mud, which 

 the musk-rats procure from the beds of streams, often 

 burrowing beneath the sandy superstratum to secure it 

 of the proper consistency. When sun-dried, these struct- 

 ures are very strong and will bear the weight of a full- 

 grown man. The walls are generally about six inches in 

 thickness, and are very difficult to pull to pieces. The 

 interior consists of a single circular chamber, with a floor 

 that is ingeniously supported on coarse sticks driven into 

 the mud, after the manner of piles, and among them are 

 laid horizontally many others, thus making a strong but 

 open foundation, upon which are placed small twigs, stiff 

 mud, and over all a layer of soft grasses. This interior 

 is arranged after the dome is completed. In the center 

 of the floor is an opening, leading by several, often six 

 or eight, diverging paths, below the water-level, and 

 extending to the nearest higher or comparatively drier 

 ground. Through these the musk-rats make their escape, 



