226 



THE REPRODUCTIVE SYSTEM 



[CH. 



It will be seen that the Zygoptera, Aeschninae and Petalurinae 

 practise endophytic oviposition, while all the rest practise exophytic 

 oviposition. Reduction, however, is not complete in the Cordule- 

 gastrinae and some Synihemini, so that these may be considered 

 in a measure as intermediate or linking forms. 



Bearing in mind the description given above of the ovipositor 

 of Synlestes, we can now easily understand 

 the process of oviposition in this genus. 

 After alighting on a reed-stem above the 

 water, the Dragonfly feels about with its 

 styles until it finds a suitable place. It 

 then everts the terebra, and makes a small 

 incision with the sharp points of the anterior 

 processes. The ends of the median pro- 

 cesses slip automatically into this small 

 slit, which is quickly enlarged by sawing 

 with their teeth. As soon as the hole is 

 made large enough to take several eggs, 

 an egg is expressed through the genital 

 pore, and guided along between the blades 

 of the terebra into the tissues of the 

 plant. Three or four eggs are placed in 

 each hole. The whole body is then 

 moved a short distance downwards, and 

 the process repeated on a new spot. 

 Further holes are made in a gradually 

 descending series, not at all regularly placed 

 (fig. 105 A). Finally, the median processes 

 are retracted, the anterior ones fall back 

 with them as their muscles relax, and the 



valves close up automatically. Other Zygoptera carry on the 

 process in the same manner, but many kinds only place one egg 

 in each incision. The eggs may be laid far above the water-level, 

 at the water-level, or well beneath it. In the last case, the 

 Dragonfly (either alone or accompanied by the male) descends 

 down the stem under the water, where it appears as if silver- 

 plated, owing to its being surrounded by a complete film 

 of air. 



Fig. 105. Oviposition of 

 Synlestes weyersi Selys. 

 A. Reed-stem with punc- 

 tures ( x J). B. A punc- 

 ture enlarged ( x 8). 

 c. Section through reed- 

 stem to shew method of 

 placing the eggs ( x 4). 

 Original. 



