MR. BELL ON THE HABITS OF ARGYRONETA AQUATICA. 3 



with air, about the size of an acorn. In this it has remained 

 stationary up to the present time. 



No. 2. — Nov. 15. In another similar vessel, also furnished with 

 a plant of Stratiotes, I placed six Argyronetce. The one now 

 referred to began to weave its beautiful web about five o'clock in 

 the afternoon. After much preliminary preparation, it ascended 

 to the surface, and obtained a bubble of air, with which it imme- 

 diately and quickly descended, and the bubble was disengaged from 

 the body, and left in connexion with the web. As the nest was, 

 on one side, in contact with the glass, enclosed in an angle formed 

 by two leaves of the Stratiotes, I could easily observe all its move- 

 ments. Presently it ascended again and brought down another 

 bubble which was similarly deposited. In this way no less than 

 fourteen journeys were performed, sometimes two or three, very 

 quickly one after another, at other times with a considerable 

 interval between them, during which the little animal was em- 

 ployed in extending and giving shape to the beautiful transparent 

 bell, getting into it, pushing it out at one place, and rounding it 

 at another, and strengthening its attachment to the supports. At 

 length it seemed to be satisfied with its dimensions, when it crept 

 into it and settled itself to rest with the head downwards. The 

 cell was now the size and nearly the form of half an acorn cut 

 transversely, the smaller and rounded part being uppermost. 



No. 3. The only difference between the movements of this and 

 the former was, that it was rather quicker in forming its cell. In 

 neither vessel was there a single bubble of oxygen evolved by the 

 plant. 



The manner in which the animal possesses itself of the bubble 

 of air is very curious, and, as far as I know, has never been ex- 

 actly described. It ascends to the surface slowly, assisted by a 

 thread attached to the leaf or other support below, and to the sur- 

 face 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 attached to the hairs 

 which cover the abdomen, but is held on by the two hinder legs, 

 which are crossed at an acute angle near their extremity ; this 

 crossing of the legs taking place at the instant the bubble is seized. 

 The little creature then descends more rapidly, and regains its 

 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 



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