INSECTS I THEIR BREATHING ORGANS. 101 



Here is a slender worm, an inch and a-half in length, 

 thickest a little behind the head, and tapering gradually to 

 a lengthened tail, the twelve divisions of the body being 

 very conspicuous. It swims up and down or to and fro 

 in the clear water with a not very rapid, wriggling move- 

 ment, throwing its body alternately from side to side in 

 the form of the letter S. 



This is the maggot of a handsome dipterous fly, some- 

 times called the Chameleon-fly (Stratiomys chameleon). 

 There is much about it to reward observation and careful 

 examination with a low magnifying power, especially the 

 head, with its pointed snout, and its pair of foot-like 

 palpi, or feelers. These are situated one on each side of 

 the head, are three-jointed, the last joint being studded 

 with short stiff spines, and the second having a thumb - 

 like projection. With these organs, the grub roots and 

 burrows among the decaying vegetable matter at the 

 bottom for its food ; and when not so engaged, they are 

 often rapidly vibrated in a singular manner, the sight of 

 which might induce a feeling of fear, as if they were 

 threatening weapons of offence a pair of poisonous stings, 

 for instance ; they have, however, no such function, the 

 poor grab being perfectly harmless. 



What I wish you chiefly to observe, however, is the 

 tail, with its curious organisation. With the naked eye, 

 you can perceive that the last joint is much slenderer 

 and more lengthened than the rest, and that it is tipped 

 with a beautiful crown of feathers, like the diadem of 

 some semi-savage prince. This is best seen when* the 

 animal comes to the surface, which it always does tail 

 uppermost ; for, as soon as the tip reaches the air, the 

 plumes instantly open, and form an exquisite cone or 

 funnel, from which every drop of moisture is excluded, 

 though the water stands around at the level of the brim. 

 A few seconds it remains motionless thus, the whole body 

 hanging downwards, suspended from the caudal coronet, 



