63 



As already mentioned the mask is an altogether unique structure 

 in the Animal Kingdom. It is made suitable for the use to which 

 it is put by the lengthening of the mentum and submentum, and 

 the alteration of the tip of the palpus into a moveable hook. The 

 mask appears at first sight to be an unwieldy implement, but it is 

 capable of being worked with accuracy and great speed. It 

 posseses much power, and it has been stated that if the naiad is 

 held by the extreme tip, it can easily lift its body up to the support. 

 The mask can be shot out so that its tip extends to some considerable 

 distance in front of the head, and this lengthy grappling arm, com- 

 bined with the sideways movement of the palpi (lateral lobes), and 

 the assistance of their teeth, constitutes a formidable instrument for 

 the capture of prey. 



Should a tiny red worm or other apparently dainty morsel be 

 sighted, the naiad creeps stealthily along by slow degrees, so as not 

 to call the attention of the prey it hopes to catch ; or perhaps just 

 as frequently it waits till the prey of its own accord approaches 

 sufficiently near. At any rate when within measurable distance, 

 which, if one maj^ judge from occasional false shots, it cannot 

 always gauge with great accuracy, the naiad puts into action 

 the powerful muscles by which the mask is operated, shoots it out 

 with lightning speed, seizes the prey with the moveable hooks, and 

 with equal speed brings back the mask with the pre}^ in its grasp. 

 Wriggle as it may the prey is helpless, and the action of the mask 

 brings it in front of the mouth, where the first maxillae and 

 mandibles soon make short work of it, struggle as it may and often 

 does. 



I am afraid I have brought forward a somewhat uninteresting 

 subject, and I know^ I have treated it most inadequately. As a 

 matter of fact our knowledge of the evolution of the remarkable 

 dragonfly labium is none too complete ; but we see clearly that the 

 steps of the process by which natural selection (or some other method 

 of adaptation) has evolved from an original pair of second maxillae, 

 the strange yet very efficient odonate mask, are well worth investiga- 

 tion, even if the objective may be difficult of attainment. 



