262 INSECT WATER TRESPASSERS. 



were out of the water, I teased several specimens of 

 Polynema natans with the point of a needle; but never 

 succeeded in making one take to its wings at least, 

 not in air. When walking on the water, however, 

 they sometimes started off suddenly ; but always kept 

 close to the surface, so that it rather seemed as if they 

 were carried by some tiny gust of air." 



Sir John Lubbock then proceeds to remark that 

 the insect has no peculiarity which indicates an aquatic 

 life, such as we see in the boat-like form and the oar 

 or paddle-like legs of the insects. No one would 

 therefore think, in case of seeing a Swimming Ichneu- 

 mon in the open air, that it had habits differing so 

 greatly from those of its kinsfolk in general. " Per, 

 mit me to say, in conclusion, that if Polynema natans 

 and Prestwichia aquatica had been extinct species, no 

 palaeontologist would have suspected that they were 

 aquatic. In the present state of our knowledge there 

 is nothing in their structure which would have sug- 

 gested such an idea." 



The wings are made after a curious fashion, but 

 certainly have no aquatic look about them. The 

 upper pair are about as long as the body, and are flat, 

 covered with hairs, and edged with a deep fringe of 

 bristles. No nervures are perceptible, even with the 

 aid of a magnifying glass, if we may except a slight 

 thickening on one of the edges. The second, or 

 lower pair of wings, could scarcely be taken for wings 

 if removed and viewed independently of the insect. 

 When the insect is at rest, these wings are crossed over 

 the back, and the hairs with which they are edged make 

 a radiating fringe round the whole of the abdomen. 



