94 LIFE-HISTORIES OF AUSTRALIAN ODONATA, iv., 



three caudal spines in other A nisojjfera larv?e) is now given 

 (Fig.6). 



The question as to whether this larva is aquatic or air- 

 breathing, is one of some difficulty. With several of the 

 larvae which 1 obtained at Medlow, I tried the following ex- 

 periments : — 



(1) They were placed in a large bottle of pure water. Those 

 which were only about half -grown, crawled about on the 

 bottom ; but the two that were nearly full-fed, rose with the 

 tip of their abdomens uppermost, and remained with it just 

 on the surface of the water, but not pushed through into the 

 air. I noticed particularly that the water-film covered the 

 anal opening, and that they drew water in and out when 

 breathing. This suggests that they preferred the best aerated 

 water to breathe in. 



(2) The larvae were all taken out of the water, and placed 

 in a box. Here they appeared very uncomfortable, and soon 

 became very inert. 



(3) They were next placed in a tin, in about an inch of 

 ooze from the swamp. This seemed to suit them fairly well. 

 They moved about somewhat quickly, breathing in large 

 quantities of the thick mud anally, and then expelling it 

 with such force, that I could follow the stream of particles 

 for several inches. I noticed, in particular, that they do not 

 use this strong anal expulsion as a means of locomotion, in 

 the manner of the Aeschnid lai'vae. Even when at rest, the 

 force of expulsion was very great. This suggests that their 

 usual method of breathing is by taking in the muddy water 

 through the anal opening, and then, having extracted the 

 oxygen from solution, the particles of mud are expelled with 

 great force. 



A further point of interest is, to determine what means 

 the larva possesses of filtering the muddy water which it 

 draws in so vigorously. If the three caudal plates that sur- 

 round the anal opening be carefully ojDened out (as in Fig.6) 

 it will be seen that the sides of the superior plate, and the 



