THE BEAVERS OF NORTH AMERICA 15 



sents what is probably the original and primitive 

 form of house. The entrances, for there are usually 

 more than one, are well below the surface of the 

 water. Then we have the next step in advance- 

 ment : the hole in the bank with the living chamber 

 coming to the surface, so that in order to make it 

 more secure against marauders and render it drier, 

 a roughly arranged pile of brush, sticks, logs, and 

 mud and grass is heaped over it. From this it 

 is but a step to the house which is entirely above 

 ground, and placed either on the bank or on an 

 island, and then the final development in which the 

 beavers make the island as a foundation. 



In appearance, the two latter types are identical 

 and both have the entrances beneath the water. 

 In building these houses or lodges, as they are more 

 commonly called, the beginning is a composition of 

 mud, brush and small sticks, from which the bark 

 is nearly always eaten. Whether the mound is 

 placed over the opening of the burrow, or whether 

 the burrow is made after the house has been started, 

 I cannot say with absolute certainty, but from 

 what I have observed of the beginnings of lodges, 

 there seems every reason to believe that the burrow 

 precedes the lodge. Gradually, as the mound 

 becomes large enough, the inside is hollowed out, 

 then more and more material is added to the out- 

 side, larger sticks and even poles or logs are used, 

 all more or less pointing to the apex, so that they 

 support each other to some extent. Water- 



