DWELLINGS. 167 



Burrows zviih barns adjoined. — Certain Rodents 

 have carried hollow dwellings to great perfection. 

 Among these the Hamster of Germany {Cricetus 

 frumentarius') is not the least ingenious. To his 

 dwelling-room he adds three or four storehouses for 

 the amassed provisions of which I have already had 

 occasion to speak. The burrow possesses two open- 

 ings : one, which the animal prefers to use, which 

 sinks vertically into the soil; the other, the passage 

 of exit with a gentle and very winding slope. The 

 bottom of the central room is carpeted with moss and 

 straw, which make it a warm and pleasant home. 

 A third tunnel starts from this sleeping chamber, 

 soon forking and leading to the wheat barns. Thus 

 during the winter the Hamster has no pressing need 

 to go out except on fine days for a little fresh air. 

 He has everything within his reach, and can remain 

 shut up with nothing to fear from the severity of the 

 season. 



Dwellings hollowed out in wood. — It is not only the 

 soil which may serve for retreat ; wood serves as an 

 asylum for numerous animals, who bore it, and find 

 in it both food and shelter. In this class must be 

 placed a large number of Worms, Insects, and Crus- 

 taceans. One of these last, the Chelura terebrans, a 

 little Amphipod, constitutes a great danger for the 

 works of man. It attacks piles sunken to support 

 structures, and undermines them to such a degree that 

 they eventually fall. Wood is formed of concentric 

 layers alternately composed of large vessels formed 

 during the summer, and smaller vessels formed during 

 the winter. The latter zones are more resistant, the 

 former are softer. When one of these Crustaceans 

 attacks a pile, it first bores a little horizontal passage, 



