THE SWIMMING ICHNEUMON FLY. 257 



THE SWIMMING ICHNEUMON FLY (Polyuema natans) . 



In the lower corner of the same illustration may be 

 seen a square space marked off, so as to separate it 

 from the rest of the figures. In it are two winged 

 insects one moderately large, and the other very 

 small. These are representations of the Swimming 

 Ichneumon, the smaller figure giving it of its real size, 

 and the larger showing it as it appears when 

 magnified. 



As we have already seen, there are plenty of swim- 

 ming insects. These, however, all propel themselves 

 by means of their legs, which are modified for that 

 purpose, and their wings are kept closely hidden 

 under the elytra. In the Swimming Ichneumon, how- 

 ever, we have a most remarkable anomaly in the 

 history of insects. The ichneumons belong to the 

 Hymenoptera i.e., the order which contains the bees, 

 wasps, ants, etc. ; and that one of these creatures 

 should swim, using its wings instead of fins, appears 

 to be an anomaly. Yet this is just what the Swimming 

 Ichneumon does, and its di.covery forms an epoch in 

 the history of entomology. 



As the reader will see from the account which 

 will presently be given, the insect was discovered 

 almost simultaneously by two individuals within a 

 week, but as one of them, Sir J. Lubbock, Bart., had 

 the precedence by a few days, the discovery belongs to 

 him. 



Similar examples of nearly simultaneous discovery 



17 



