252 roruLAR histouy of the aquauium. 



animal possesses itself of the bubble of air is very curious, 

 and, as far as 1 know, has never been accurately described. 

 It ascends to the surface slowly, assisted by a thread attached 

 to the leaf, or other support below, and to the surface of the 

 water. As soon as it comes near the surface, it turns with 

 the extremity of the abdomen upwards and exposes a portion 

 of the body to the air for an instant; then with a jerk it 

 snatches, as it were, a bubble of air, which is not only at- 

 tached to the hairs which cover the abdomen, but is held on 

 by the two hinder legs, which are crossed at an acute angle 

 near the extremity; this crossing of legs takes place at the 

 instant the bubble is seized. The little creature then de- 

 scends more rapidly, and regains the cell always by the 

 same route, turns the abdomen within it and disengages the 

 bubble. 



"No. 4. Several of them when I received them had the 

 hair on the abdomen wetted, and I placed them on the 

 blotting paper till they were dry. On returning them 

 to the water, two remained underneath a floating piece 

 of cork, and the hair, being now dry, retained the pel- 

 licle of air which is ordinarily observed. One of the two 

 came out of the water, attached the cork to the glass, and 

 wove a web against the latter, against which it rested about 



