XIII 



ARACHNIDA 



193 



Water Spider (Argyroueta aquatica). 



The Water Spider is fairly common in our ponds, and is a 

 most interesting inmate of an aquarium, where, if supplied with 

 a few long sprays of water-weed, she will soon begin to weave 

 her very beautiful 

 little web. This 

 is at first horizon- 

 tal, but in time 

 becomes dome- 

 shaped (Fig. 125, 

 N) owing to the 

 air which the 

 spider brings 

 down from the 

 surface and dis- 

 charges below it. 

 This air is carried 

 in a bubble adher- 

 ing to the hairs 

 on her abdomen 

 (Fig. _ 125, b). 

 Sometimes she 

 supports it also 

 with her hind- 

 legs, as she carries 

 it down ; finally 

 she discharges it 

 below her web 

 by brushing it 

 off with her legs. 

 The bubbles rise 

 and become en- 

 tangled in the 

 web, raising it, until when sufficient air for the needs of the 

 spider has been brought down the web may have attained 

 a shape such as that shown in Fig. 125, N, although it is not 

 always so lofty as this. 



This " web " is usually known as the spider's " nest," for 

 it is not used as a snare, but as the lady spider's home, 

 where she retreats when she has caught food at the surface 

 VOL. i O 



FIG. 125. The Common Water Spider 



(Argyroneta aquatica). 



The spider carrying down a bubble of air (V) ; N, the 

 dome-shaped web or " nest." 



