68 POND LIFE 



rejoices in being the only British example of that genus. It 

 is a most astonishing insect, so thin indeed that the pond-skater 

 seems over-nourished in comparison. Its body, ^ of an inch 

 in diameter, is elongated, and forms a surprisingly long head 

 terminating in a beak. The head, which is longer than the 

 thorax, becomes narrower until it reaches the antennae, where 

 it again thickens. 



The eyes, which are small and very prominent, are situated on 

 the sides of the head, near the middle. 



But the most surprising thing about the creature is its limbs, 

 for each leg resembles a hair in fineness. The entire insect is 

 so fragile that one wonders that it can exist at all. Owing to 

 its extraordinary thinness, the water-gnat is very difficult 

 to find, and constantly causes much surprise when it slowly 

 emerges from amongst the weeds, which have been most care- 

 fully examined. 



Similar to its relatives the pond-skaters, Hydrometra stag- 

 norum preys upon any unfortunate insects that may come in 

 its way. 



SPRINGTAILS 



Although springtails frequent practically all ponds and 

 streams, yet very few people have ever seen one of these queer 

 little insects. They are so small that they readily escape ob- 

 servation, unless particularly looked for. There are several 

 British species. Podura aquatica, one of the commonest, is a 

 blue-coloured insect strangely clumsy in shape, with three pairs 

 of legs, each furnished with a sharp claw. The antennae are 

 short and thick and the eyes prominent. Wings it has none, 

 although it is a member of the Insecta. 



They usually congregate in large numbers and appear as a 

 little patch of blue dust on the surface of the water. Should 

 we by means of a stick disturb such an assembly, the little 

 creatures very soon show that they are far less inanimate than 

 they appear to be, for without a moment's delay they disperse 

 in all directions. The rapidity with which they escape and the 

 distance they travel compared with their size is certainly most 

 astonishing, until one of these small insects is carefully ex- 

 amined. Under the microscope a peculiar forked arrangement 

 will be noticed. It is attached to the end of the abdomen and 

 is held when walking tightly pressed against the body. This 

 appendage is called the spring, and is used for the purpose its 

 name implies. 



By taking advantage of the elasticity of the water-film, and 



