THE ANIMAL KINGDOM. 201 



riously hollow out for themselves a refuge in the hardest 

 bodies, even metals. The most extraordinary animal of this 

 kind that is known is a powerful hymenopterous insect, the 

 Giant Sirex, the larva of which, during the expedition to 

 the Crimea, gnawed the balls in the soldiers' cartridges, and 

 bored deep holes in them in which it might find a secure 

 shelter. Marshal Vaillant presented to the Academy of 

 Sciences several balls which had been pierced through in 

 this way by these insects. 



Several of these metal-eaters might be mentioned. The 

 larvae of a Cetonia, as has been known for a considerable 

 time, sometimes pierce the lead coverings of our roofs ; and 

 a piece of the gutter of a church, which presented numer- 

 ous perforations produced by a Callidia, was brought to me 

 recently at the museum at Rouen. 



CHAPTER X. 



HYDRAULIC ENGINEERS AND MASONS. 



The diving-bell was invented by a little spider ; we had 

 nothing to do but imitate it ; the copyist has, however, not 

 equalled the inventor. In fact, the insect builds below 

 water, beginning and finishing its task there, and it is only 

 when its work is completed that it fills the structure with 

 vital air. 



It is a charming little house of silk, which suffices for all 

 the wants of its occupant. Here it passes the winter and 

 rears its young ; and when it is pressed by hunger, the bell 



