INSECTS: THEIR BREATHING ORGANS 121 



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

 times called the Chameleon-fly (Stratiomys chamcekon). 

 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. 

 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 grub being perfectly harmless. 



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

 tail, with its curious organization. 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 downward, sus- 

 pended from the caudal coronet, then suddenly the tips 

 of the plumes curve inward toward each other, enclosing 

 a globule of air, and the animal wriggles away into the 

 depths, carrying its burden, like a pearl, or a glittering 



bubble of quicksilver, behind it. 

 15 SCIENCE 6 



