274 INSECT WATER TRESPASSERS. 



air free. Thus, there is an exact analogy between the 

 old diving-bell and the home of the Water Spider the 

 cocoon representing the bell, and the bubble enclosed 

 by the legs taking the place of the air vessels. 



Perhaps the reader may ask what may be the real 

 object of this structure, seeing that the Spider can 

 catch its prey in the water, eat it ashore, and hide 

 itself on land like any of its terrestrial brethren ? As 

 has already been stated, the cocoon does act as a place 

 of refuge, but its chief object is to serve as a protec- 

 tion for the young. For, singular to state, not only 

 does the mother Spider, herself an air-breathing crea- 

 ture, pass much of her time under the water, but her 

 eggs are hatched and her young are nurtured beneath 

 the water, and never go into the outside air until 

 they are strong enough to shift for themselves. On 

 an average, one hundred little spiders are hatched 

 simultaneously in this subaquatic residence. 



When the Spider deposits her eggs, she fastens 

 them to the top of the cocoon, so that they receive the 

 benefit of any air that is contained in it, and then 

 covers them with a circular plate of very tough threads. 

 Similar coverings may be seen on the eggs of many 

 terrestrial spiders, especially those which belong to the 

 genus Agelena. 



Some twelve years ago, I mentioned that a gradual 

 but steady destruction of the Spider was taking place, 

 in consequence of the great demand for it as an inha- 

 bitant of the fresh-water aquarium. This destruction 

 has gone on so fast, that in many localities where the 

 Water Spider was once plentiful, an absolute extirpa- 

 tion has taken place. 



