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. g^.Pafirius 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. 



