NATURAL HISTORY. 109 



The houses of the Beaver are built of mud, stones, and 

 sticks. They are placed in a stream, and their entrance is 

 always below the surface. As a severe frost would freeze up 

 their doors, it is necessary to make the stream deep enough to 

 prevent the frost from reaching the entrances. This is done 

 by building a dam across the river, to keep back the water 

 until it is sufficiently deep for the beaver's purposes. These 

 banks are made of branches which the Beaver cuts down with 

 its strong sharp teeth, and of mud and stones. The Beavers 

 throw these branches into the water, and sink them to the 

 bottom by means of stones ; by continually throwing in fresh 



CASTOR. (Gr. Kuorcop, a Beaver.) 



Fiber (Lat a Beaver), the Beaver. 



supplies a strong embankment is soon made. As many Beav- 

 ers live together in one society, the formation of a dam docs 

 not take very long. By their united efforts they rapidly fell 

 even large trees by gnawing them round the trunk, and al- 

 ways taking care to make them fall towards the water, so that 

 they can transport the logs easily. The mud and stones used 

 in their embankments are not carried on their tails, as some 

 say, nor do the Beavers use their tails as trowels for laying 

 on the mud, the fact being that the stones and mud are car- 

 ried between their chin and fore-paws, and the mistake re- 

 specting the tail is evidently caused by the slap that Beavers 



