302 The Hunting Wasps 



eel-trap precisely. Lastly, grains of sand, kept 

 in reserve inside, are laid one by one upon this 

 silken foundation and glued together with silky 

 slime. Having finished this lid, the larva has 

 nothing else to do but give the last finish to the 

 inside of the abode and glaze the walls with 

 varnish to protect its delicate skin against the 

 rough sand. 



The hammock of pure silk and the hemisphere 

 that closes it later are, as we see, but a scaffold- 

 ing intended to support the masonry of sand 

 and give it a regular curve ; they might be 

 compared with the wooden moulds which 

 builders set up when constructing an arch, a 

 vault. Once the work is done, the timber frame 

 is taken away and the vault is sustained by 

 virtue of its perfect balance. Even so, when the 

 cocoon is finished, the silken support disappears, 

 partly lost in the masonry, partly destroyed by 

 contact with the coarse earth ; and not a trace 

 remains of the ingenious method followed in 

 welding together materials with so little con- 

 sistency as sand into a building of such perfect 

 regularity. 



The round cap closing the mouth of the 

 original eel-trap is a work apart, adjusted to 

 the main body of the cocoon. However well the 

 two parts are fitted and soldered, the solidity is 

 not the same as the larva would obtain if it 



