208 THYSANOURA. PODURID^. 



In the P.ODURIDJS, the appendages to the sides of the abdomen 

 are wanting ; but the extremity of it is prolonged into a forked 

 tail, by which these insects can execute very surprising leaps. 



This, when not in action, is bent 

 forwards beneath the abdomen ; 

 an< ^ it i s by the sudden ex- 

 tension of it, that the leap is 

 produced. From this con- 

 f \ formation, the Poduras are 



Fro. 434.-PODUHA. commonly known under the 



name of Spring -tails. The 



scales with which their bodies are covered, are objects of 

 great interest to the Microscopist ; for they have a most 

 elaborate and minute structure, which can only be made out by 

 instruments of the best quality ; hence they are very valuable 

 test objects. 



