234 THE INDUSTRIES OF ANIMALS. 



Dwellings built of hard materials united by mortar. 

 — Among mammals few animals have become so 

 skilful in the art of building houses as the insects 

 we have just been considering. There are, however, 

 two who equal if they do not surpass them — the 

 Musk-rat and its relative, the Beaver. 



The Musk-rats of Canada live in colonies on the 

 banks of streams or deep lakes, and construct dwell- 

 ings which are very well arranged. In their methods 

 we find combined the woven shelter with the house of 

 built earth. Their cabins are established over the 

 highest level of the water and look like little domes. 

 In building them the animals begin by placing reeds 

 in the earth ; these they interlace and weave so as to_ 

 form a sort of vertical mat. They plaster it externally 

 with a layer of mud, which is mixed by means of the 

 paws and smoothed by the tail. At the upper part of 

 the hut the reeds are not pressed together or covered 

 with earth, so that the air may be renewed in the in- 

 terior. A dwelling of this kind, intended to house six 

 or eight individuals who have combined to build it, 

 may measure up to 65 centimetres in diameter. There 

 is no door directly opening on to the ground. A sub- 

 terranean gallery starts from the floor and opens out 

 beneath the water. It presents secondary branches, 

 some horizontal, through which the animal goes in 

 search of roots for food, while others descend verti- 

 cally to pits specially reserved for the disposal of 

 ordure. 



But it is, above all, the Beaver {Castor fiber) who 

 exhibits the highest qualities as an engineer and 

 mason. This industrious and sagacious Rodent is well 

 adapted to inconvenience the partisans of instinct as 

 an entity, apart from intelligence, which renders 



