THYSANURA. 85 



water appear to be covered by a moving mass of minute 

 grains which become more active when disturbed. These 

 masses as well as the dark specks on snow consist of thou- 

 sands of little creatures that are provided with a wonderful 

 means of jumping. There is on the end of the body a tail-like 

 organ that is bent under when the insect is at rest, and that 

 reaches almost to the head ; this when suddenly straightened 

 throws the insect high in the air and several feet away. This 

 action is like a spring-board jump, only these little fellows 

 always carry their spring-boards with them, and have thus 

 won the name of Spring-tails. The species upon snow, called 

 the Snow-flea, Achorutes nivicola (Ach-o-ru'tes ni-vic'o-la), 

 sometimes proves a nuisance in maple sugar-bushes by get- 

 ting into the sap. Through a micro- 

 scope a Spring-tail appears very ab- 

 surd, it has long antennae and large, 

 dark eye-spots on the face, which, to- 

 gether with the longhair that sticks 

 forward on the head and thorax, 

 give the creature a look of solemn 



. Fig. 93. — Papirius fuscus. (After 



fierceness. Different species may Lubbock > 



be found at almost any time of the year in damp places. 

 Figure 93 represents one of these. In many forms the 

 body is much more slender than in that figured 



